Analisi della fase di start-up di un bireattore a membrana.

INFLUENZA DELL‟URBANIZZAZIONE SULLO STATO DI QUALITÀ DEI CORPI IDRICI RICETTORI ATTRAVERSO UN APPROCCIO DI TIPO INTEGRATO

Il cambiamento climatico è una delle principali cause che possono indurre a una modifica delle caratteristiche idrologiche e ambientali dei bacini naturali. Per quanto attiene la qualità delle acque naturali superficiali, tale fattore va combinato con quello antropogenico (urbanizzazione, variazione di popolazione e domanda idrica, etc.), che può ridurre o incrementare l‟effetto delle variazioni climatiche. Un aspetto che merita un‟attenta valutazione è l‟analisi degli effetti che i cambiamenti sia climatici che antropogenici hanno sulla qualità di un corpo idrico ricettore. Al fine di valutare tali effetti, nel presente studio è stato impiegato un modello di tipo integrato messo a punto in…

Uncertainty assessment of a membrane bioreactor model using the GLUE methodology

A mathematical model for the simulation of physical-biological organic removal by means of a membrane bioreactor (MBR) has been previously developed and tested. This paper presents an analysis of the uncertainty of the MBR model. Particularly, the research explores the applicability of the Generalised Likelihood Uncertainty Estimation (GLUE) methodology that is one of the most widely used methods for investigating the uncertainties in the hydrology and that now on is spreading in other research field. For the application of the GLUE methodology, several Monte Carlo simulations have been run varying the all model influential parameters simultaneously. The model was applied to an MBR pilot pl…

Comparison between MBR and MB-MBR pilot plants subject to a gradual salinity increase: analysis of biokinetic and fouling behaviour

Two pilot plants were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were studied. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the pore foulin…

Membrane Fouling Mitigation in MBR via the Feast–Famine Strategy to Enhance PHA Production by Activated Sludge

Fouling is considered one of the main drawbacks of membrane bioreactor (MBR) technology. Among the main fouling agents, extracellular polymeric substances (EPS) are considered one of the most impactful since they cause the decrease of sludge filterability and decline of membrane flux in the long term. The present study investigated a biological strategy to reduce the membrane-fouling tendency in MBR systems. This consisted of seeding the reactor with activated sludge enriched in microorganisms with polyhydroxyalkanoate (PHA) storage ability and by imposing proper operating conditions to drive the carbon toward intracellular (PHA) rather than extracellular (EPS) accumulation. For that purpos…

Analysis of Biomass Characteristics in MBR and MB-MBR Systems Fed with Synthetic Wastewater: Influence of a Gradual Salinity Increase

The paper presents the results of a field gathering campaign carried out on two different pilot scale membrane bioreactor (MBR) systems, treating synthetic wastewater subject to a gradual increase of salinity. One was a conventional MBR system, while the other was a moving bed biofilm membrane bioreactor (MB-MBR), which combines suspended biomass and biofilm. Indeed, the presence of suspended carriers inside the bioreactor seems to give benefits due to the collisions between the circulating media and the membrane. The aim of the study was the comparison of two configurations in terms of biomass activity characterization and performance (pollutants removal and hydraulic behaviour). The resul…

Quantification of kinetic parameters for heterotrophic bacteria via respirometry in a hybrid reactor

Over the last decade new technologies are emerging even more for wastewater treatment. Among the new technologies, a recent possible solution regards Moving Bed Biofilm Reactors (MBBRs) that represent an effective alternative to conventional processes. More specifically such systems consist in the introduction of plastic elements inside the aerobic reactor as carrier material for the growth of attached biomass. Recently, one of the mostly used alternatives is to couple the Moving Bed Biofilm Reactor (MBBR) process with the conventional activated sludge process, and the resulting process is usually called HMBBR (Hybrid MBBR). In the MBBR process the biofilm grows attached on small plastic el…

Assessing Methane Emission and Economic Viability of Energy Exploitation in a Typical Sicilian Municipal Solid Waste Landfill

Sanitary landfills for municipal solid waste (MSW) represent one of the major anthropogenic source of GHGs emissions and are directly responsible of the climate changes we are facing nowadays. Indeed, the biodegradable organic matter of MSW undergoes anaerobic digestion producing the landfill gas (LFG), whose main components are CH4 and CO2. Therefore, biomethane energy exploitation in MSW landfills will reduce GHGs emission positively affecting the global warming. The aim of the present study was to assess the methane production in a Sicilian landfill by comparing the results from field measurements of methane emission and the estimates achieved by applying different mathematical models. A…

The role of fouling mechanisms in a submerged membrane bioreactor during the start-up

Modelling biological nitrogen and phosphorus removal with soluble microbial products (SMP) production-degradation processes

Over the last two decades, Membrane Bioreactors (MBR) are increasingly used for wastewater treatment. Mathematical modelling of MBR systems has played a key role in order to better explain the effect of their peculiarities. Indeed, several MBR models have been presented in literature in order to improve the knowledge on MBR systems: biological models, hybrid models which include soluble microbial product (SMP) modelling, physical models able to describe the membrane fouling and integrated models which couple the hybrid models with the physical ones. However, among the existing MBR models only few integrated models have been developed which take into account the existing relationship between…

Wastewater modification processes assessment in a stabilization reservoir.

A semi-empirical mechanistic model able to simulate the dynamics of a stabilization reservoir was developed incorporating both settling of particulate components and chemical/biological processes. Several factors affecting the reservoir effluent quality were taken into account: hydraulics and hydrology, solar radiation, atmospheric reaeration, algae, zooplankton, organic matter, pathogen bacteria, and sediment-water interaction. The model quantifies the specific influence of each factor on effluent quality, evaluating the correlation between the different considered factors. State variables included in the model were: algae, dissolved oxygen, organic matter, zooplankton and indicator bacter…

Estimation of methane emission by a municipal landfill: the case of Palermo

CH4 diffuse emissions from municipal solid waste landfills represent one of the most important anthropogenic source of greenhouse-gas. CH4 is produced by anaerobic biodegradation of organic matter in land-filled MSW and it constitutes the major component of landfill gas. Gas recovery is a suitable tool to effectively control CH4 emissions from landfill sites and the quantification of CH4 emissions represents a good tool to evaluate the effectiveness of biogas recovering system in reducing biogas emission. In particular, LFG emissions can be indirectly evaluated from mass balance equations between formation, recovery and oxidation of biogas in the landfill, as well as on a direct approach ba…

Role of modeling uncertainty in the estimation of climate and socioeconomic impact on river water quality. J. of Water Resources Planning and Management – Asce, 138(5), 479–490.

Climate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty and the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based on limi…

Challenges and opportunities for citrus wastewater management and valorisation: A review.

Citrus wastewaters (CWWs) are by-products of the citrus fruit transformation process. Currently, more than 700 million of m³ of CWWs per year are produced worldwide. Until nowadays, the management of CWWs is based on a take-make-use-dispose model. Indeed, after being produced within a citrus processing industry, CWWs are subjected to treatment and then discharged into the environment. Now, the European Union is pushing towards a take-make-use-reuse management model, which suggests to provide for the minimization of residual pollutants simultaneously with their exploitation through a biorefinery concept. Indeed, the recovery of energy nutrients and other value-added products held by CWWs may…

Foaming estimation tests in activated sludge systems.

Persistent biological foaming phenomena in activated sludge systems due to excess of filamentous microorganisms with hydrophobic properties, such as GALO, Microthrix parvicella and others, are frequently reported everywhere. Nevertheless, even if the number of plants affected by this trouble is high, presently there are no suitable general methods to evaluate properly the phenomenon. This paper reports on the results of a series of foam tests (Scum Index, Foam Rating), of hydrophobicity measurements of activated sludge (mixed liquor and foam) and measurements of extension of aeration tank covered by foam surfaces. The data obtained by using the above indicated methods are clearly correlated…

BIODIVERSITA’ DELLE COMUNITA’ BATTERICHE IN UN SUOLO SOTTOPOSTO A BIORISANAMENTO IN MICROCOSMO

Gli idrocarburi (HC) sono uno dei principali inquinanti ambientali. Una tecnologia promettente per il trattamento di siti contaminati si basa sulla biodegradazione degli inquinanti da parte di popolazioni microbiche capaci di utilizzare HC come fonte di carbonio ed energia (Biorisanamento). La necessità di risanare siti contaminati richiede da una parte la caratterizzazione delle comunità microbiche coinvolte nella biodegradazione, dall’altra lo sviluppo di interventi volti a migliorare il potenziale metabolico dei microrganismi degradatori. La nostra attività di ricerca ha avuto come obiettivo quello di caratterizzare e analizzare la biodiversità di comunità microbiche di un suolo contamin…

Start-up of a submerged membrane bioreactor with complete sludge retention

Effect of biomass features on oxygen transfer in conventional activated sludge and membrane bioreactor systems

Abstract The aim of the present study was to compare the oxygen transfer efficiency in a conventional activated sludge and a membrane bioreactor system. The oxygen transfer was evaluated by means of the oxygen transfer coefficient and α-factor calculation, under different total suspended solids concentration, extracellular polymeric substances, sludge apparent viscosity and size of the flocs. The oxygen transfer coefficient and α-factor showed an exponential decreasing trend with total suspended solid, with a stronger oxygen transfer coefficient dependence in the conventional activated sludge compared to the membrane bioreactor. It was noted that the oxygen transfer coefficient in the conve…

IL NOCCIOLINO DI OLIVE COME SUBSTRATO ORGANICO PER LA DENITRIFICAZIONE BIOLOGICA DELLE ACQUE DI FALDA

La denitrificazione biologica come trattamento in situ delle falde contaminate ha riscosso grande interesse negli ultimi decenni; coniuga l’efficacia di rimozione ai costi relativamente contenuti se , confrontati con altre metodiche di intervento. La resa di tale tecnologia di trattamento è fortemente condizionata dalla scelta del materiale reattivo che fornisce il carbonio organico necessario a sostenere il processo. Diversi studi hanno evidenziato la possibilità di operare la denitrificazione biologica a partire da substrati di natura legnosa (segatura, corteccia, etc.). In tale ottica, la nota presenta i risultati preliminari ottenuti utilizzando come substrato il nocciolino di olive tri…

Occurrence of illicit drugs in two wastewater treatment plants in the South of Italy

In this study the occurrence and the behavior of illicit drugs and their metabolites have been investigated for two wastewater treatment plants (WWTPs) (namely, WWTP-1 and WWTP-2) located in Sicily (island of Italy). Samples were analyzed for methamphetamine, cocaine (COC), 3,4-methylenedioxymethamphetamine (MDMA), methadone (METH), 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), 3,4-methylenedioxy amphetamine (MDA); 3,4-methylenedioxy ethylamphetamine (MDEA), 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and Benzoylecgonine (BEG). The BEG, COC, MOR and THC-COOH were found at the highest concentration in both WWTPs. The Wastewater-based epidemiology calculation for BEG, COC…

A mathematical model for a sequential batch membrane bioreactor pilot plant

A mathematical model to quantify the nitrogen removal for a membrane bioreactor (MBR) has been presented in this study. The model has been applied to a pilot plant having a pre-denitrification MBR scheme. The pilot plant was cyclically filled with real saline wastewater according to the fill-draw-batch operation. The model was calibrated by adopting a specific protocol based on extensive field dataset. The Standardized Regression Coefficient (SRC) method was adopted to select the most influential model factors to be calibrated. Results related to the SRC method have shown that model factors of the efficiency of backwashing and the biological factors affecting the soluble microbial products …

Modelling the integrated urban drainage systems.

Development of an Integrated Urban Drainage System Model for the River Pollution Control

Estimation of chlorine residual in a drinking water distribution system.

Integrated urban water modelling with uncertainty analysis

In the last twenty years, the scientific world has paid particular care towards the problems that involve the environment. Accordingly, several researches were developed to describe phenomena that take place during both wet and dry periods and to increase the knowledge in this field. In particular, attention was addressed towards the problems linked with receiving water body pollution because of the impact of rain water in the urban environment. In order to obtain a good description of the problem, it is important to analyse both quantity and quality aspects connected with all the transformation phases that characterise the urban water cycle. Today, according to this point, integrated model…

Assessment of the embodied energy for manufacturing and laying a submarine outfall pipeline

The Life Cycle Assessment (LCA) methodology was applied to a submarine outfall pipeline intended for the disposal of treated MWW in the South Tyrrhenian Sea, on Western Coast of Sicily. The pipe serves 115 thousands inhabitants; it is 3,1 km long with an outer diameter of 800 mm and is allocated in a submarine trench down to 18 m bsl. The pipe ends with a multiport diffuser with outer diameter 500 mm. The whole pipeline is made in HDPE and is statically stabilized by cast iron rings and concrete anchor blocks. From the detailed constructive project of the pipeline the most relevant items involved were drawn and the most important ones were selected, both as materials employed and as laying …

Simplified model to evaluate the fate of micropollutants in an integrated urban drainage system: sensitivity analysis

The paper presents the sensitivity analysis of an integrated urban water quality system by means of the global sensitivity analysis (GSA). Specifically, an home-made integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole - SMX). The model takes into account also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and the receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Five scenarios each characterized by different combinations of sub-systems (i.e., SS, WWTP and…

Assessment of the integrated urban water quality model complexity through identifiability analysis

Urban sources of water pollution have often been cited as the primary cause of poor water quality in receiving water bodies (RWB), and recently many studies have been conducted to investigate both continuous sources, such as wastewater-treatment plant (WWTP) effluents, and intermittent sources, such as combined sewer overflows (CSOs). An urban drainage system must be considered jointly, i.e., by means of an integrated approach. However, although the benefits of an integrated approach have been widely demonstrated, several aspects have prevented its wide application, such as the scarcity of field data for not only the input and output variables but also parameters that govern intermediate st…

A practical protocol for calibration of nutrient removal wastewater treatment models

Activated sludge models can be very useful for designing and managing wastewater treatment plants (WWTPs). However, as with every model, they need to be calibrated for correct and reliable application. Activated sludge model calibration is still a crucial point that needs appropriate guidance. Indeed, although calibration protocols have been developed, the model calibration still represents the main bottleneck to modelling. This paper presents a procedure for the calibration of an activated sludge model based on a comprehensive sensitivity analysis and a novel step-wise Monte Carlo-based calibration of the subset of influential parameters. In the proposed procedure the complex calibration i…

BIOLOGICAL DENITRIFICATION OF GROUNDWATER: BIO-PRB COLUMN TEST PERFORMANCES EVALUATION

The occurrence of nitrates in groundwater is steadily raising concern due to possible health consequences of nitrate ingestion. Biological denitrification in BIO-PRB is the enhancement of a natural process that occurs naturally when bacteria live in an environment void of oxygen with carbon availability. Bio-PRB represent a perspective of development for PRB technique but, despite the fact that this technology has already been widely used for chlorinated solvents, data on denitrification PRBs are still scarce. This paper reports on the results of an experimental study carried out for 214 days on a bench-scale pilot column (10 cm in internal diameter and 100 cm in length with sampling ports …

Membrane Bioreactors for wastewater reuse: Respirometric assessment of biomass activity during a two year survey

Abstract Stricter effluent limits, water shortage conditions, land availability requires today even more the needs of advanced wastewater treatments. Attractive solutions come from membrane bioreactors (MBR), Integrated Fixed Film Activated Sludge (IFAS) or combinations (i.e., IFAS-MBRs). One crucial aspect for the applicability of this overall new technology, compared to the conventional activated sludge systems, is the lack of knowledge for design and manage (e.g., kinetic constants, optimal operative conditions etc.). In view of the above frame, the aim of the present study was to assess the kinetic and stoichiometric parameters of bacterial species in MBRs by means of respirometric tech…

The role of fouling mechanisms in a membrane bioreactor.

The present study has aimed to quantify the role of pore blocking and cake layer in a laboratory scale hollow fibre membrane module in submerged configuration. The membrane reactor (MBR) was fed with raw wastewater, only screened with a 2-mm sieve, collected from the Palermo WWTP. The MBR was characterised by an operating volume of 190 L and equipped with an aeration system located on the bottom of the reactor. The MBR operated for 65 days. The permeate was extracted by imposing a constant flux through the membrane (21 Lh−1m−2). The results confirm the importance of pore blocking control during start-up. In particular, it provides a rapid irreversible fouling that takes place at the beginni…

The role of EPS in fouling and foaming phenomena occurring in an UCT-MBR pilot plant

The aim of this study is to detect a possible relationship between EPS and fouling and EPS and foaming in a University Cape Town (UCT) membrane bioreactor (MBR) pilot plant. The UCT-MBR pilot plant was fed with 40 L/h of real wastewater and monitored for 165 days. Specifically physical/chemical features of influent, permeate and mixed liquor in different sections were analyzed. The fouling phenomenon was studied monitoring the hydraulic resistances of the membrane. The extracellular polymeric substances (EPSs) concentration inside the aerobic tank were also measured. The foaming phenomenon was monitored by performing the Foam Power and Scum Index testes. Results have shown a high correlatio…

OSSERVATORIO SUGLI IMPIANTI DI DEPURAZIONE MBR - Rapporto 2016

I reattori biologici a membrana (MBR, dall’inglese Membrane Biological Reactor) derivano dall’accoppiamento dei tradizionali processi a biomassa sospesa con i processi di filtrazione su membrane microporose o ultraporose, a seconda delle dimensioni nominali dei pori. I maggiori vantaggi legati a questa tecnologia vanno ricercati nella possibilità di eliminare, a valle della fase biologica, quella dei vincoli gestionali ed operativi a quest’ultima connessi. La sostituzione della sedimentazione con una fase di filtrazione su membrane comporta: una notevole riduzione dell’ingombro planimetrico dell’impianto di depurazione, dovuta sia alla eliminazione delle unità di sedimentazione che alla d…

Suspended and attached biomass in an mbr system treating high strength wastewater Loads

abstract

Biological groundwater denitrification systems: Lab-scale trials aimed at nitrous oxide production and emission assessment

Bio-trenches are a sustainable option for treating nitrate contamination in groundwater. However, a possible side effect of this technology is the production of nitrous oxide, a greenhouse gas that can be found both dissolved in the liquid effluent as well as emitted as off gas. The aim of this study was to analyze NO3 − removal and N2O production in lab-scale column trials. The column contained olive nut as organic carbon media. The experimental study was divided into three phases (I, II and III) each characterized by different inlet NO3 − concentrations (30, 50, 75 mg NO3-N L−1 respectively). Sampling ports deployed along the length of the column allowed to observe the denitrification pro…

Modificazione delle caratteristiche delle acque reflue a seguito del loro stoccaggio

High salinity slops treatment through a biofilm-MBR inoculated with halophilic bacteria

Oily wastewater generated, in amounts of millions of tons per year, by ships mainly in engine-rooms (bilge waters) and by washing oil tanks (slops) create a major disposal problem throughout the world because of the persistence and accumulation of xenobiotic compounds in the environment. The high salinity levels (up to 25.000 p.p.m.) and the pollutants concentration limit the chances of discharge into the sewer systems and address the disposal to the sea. This situation severely lowers the discharge limits for most of the “sensible” parameters, such both COD and hydrocarbons. Slops are usually treated by ASP with pretreatment of oil/water separation. There are limited investigations on the …

Valutazione dell'inquinamento proveniente da fonti concentrate e diffuse in un bacino mediterraneo

Separate and combined sewer systems: a long-term modelling approach

Sewer systems convey mostly dry weather flow, coming from domestic and industrial sanitary sewage as well as infiltration flow, and stormwater due to meteoric precipitations. Traditionally, in urban drainage two types of sewer systems are adopted: separate and combined sewers. The former convey dry and wet weather flow separately into two different networks, while the latter convey dry and wet weather flow together. Which is the best solution in terms of cost-benefit analysis still remains a controversial subject. The present study was aimed at comparing the pollution loads discharged to receiving bodies by Wastewater Treatment Plant (WWTP) and Combined Sewer Overflow (CSO) for different ki…

Respirometry for the Characterization of Heterotrophic Biomass Activity: Application to a MBR Pilot Plant Operated with Two Different Start-Up Strategies

A membrane bioreactor (MBR) pilot plant was operated in two subsequent experimental periods (namely, Periods I and II) with different start-up and sludge withdrawal strategies to study its peculiar biokinetic behavior by using respirometric techniques. Two extreme operational conditions were chosen to investigate the different biomass activity under dynamic or pseudostationary conditions during and after the start-up phases. Particularly, the MBR pilot plant was operated with the same volumetric loading rate (VLR) and permeate flux but differently managed during the start-up phase. In Period I, the MBR pilot plant was started up without sludge inoculum and operated without sludge withdrawal…

Biopolymer Recovery from Aerobic Granular Sludge and Conventional Flocculent Sludge in Treating Industrial Wastewater: Preliminary Analysis of Different Carbon Routes for Organic Carbon Utilization

The recovery of biopolymers from sewage sludge could be a crucial step in implementing circular economy principles in wastewater treatment plants (WWTP). In this frame, the present study was aimed at evaluating the simultaneous production of polyhydroxyalkanoates (PHA) and extracellular polymeric substances (EPS) obtainable from the treatment of agro-industrial wastewater. Two biological enrichment systems, aerobic granular sludge (AGS) and a conventional activated sludge operating as a sequencing batch reactor (SBR), were monitored for 204 and 186 days, respectively. The maximum biopolymers accumulation capacity was close to 0.60 mgPHA-EPS gVSS−1 in the AGS when operating at 3 kgCODm…

Zonazione dei parametri di decadimento del cloro nelle reti idriche: applicazione alla sottorete “Oreto-Stazione” di Palermo.

L’analisi della qualità dei corpi idrici a carattere torrentizio: un approccio modellistica per la valutazione deli interventi di risanamento.

BIOLOGICAL STABILITY ANALYSIS OF THE OFMSW MATRIX TREATED IN A COMPOSTING PLANT

Composting, mechanical-biological treatment (MBT), biodrying and biostabilization processes of pre-selected organic fraction from municipal solid wastes (OFMSW) have recently become important in municipal solid waste management. Through these treatment processes the potential impacts of the produced wastes and the volume to treat in the landfill are strongly reduced. However, the residual organic matter contained in the treated fraction may provide negative effects when e.g. the treated OFMSW is used as compost. The biological stability degree of the treated matrix provides usefull informations for the final use of it. Indeed, knowing the degree of biological stability of the compost makes …

Urban Storm-Water Quality Management: Centralized versus Source Control

The continuous growth of urban areas and the increasing public awareness of the environmental impacts of storm water have raised interest on the quality of the receiving water bodies. In the past two decades, many efforts have been directed at improving urban drainage systems by introducing mitigation measures to limit the negative environmental impacts of storm water. These mitigation measures are generally called best management practices (BMPs), sustainable urban drainage systems, or low impact developments, and they include practices such as infiltration and storage tanks that reduce the peak flow and retain some of the polluting materials. Choosing the best mitigation measure is still …

Batch Test Evaluation of Four Organic Substrates Suitable for Biological Groundwater Denitrification

Nitrates pollution represents nowadays a serious issue related to the quality of groundwater; continuous growth of industrial-scale agricultures lead to an increase of nitrates content in groundwater in the last years. Several technologies have been validated as capable to promote in situ biological nitrates remediation, such as permeable reactive barriers (PRB), biotrench, biobarriers etc. These technologies are all characterised by the use of organic substrate that act as a slow release carbon source. In free dissolved oxygen absence, such organic carbon is further oxidised, by heterotrophic bacteria naturally present in soil, in compliance to anoxic metabolism by using nitrates bound oxy…

Evaluation of greenhouse gas emissions from membrane bioreactors: development of a new mathematical model

Biological nutrient removal in a UCT-MBR pilot

In the last years, there has been an increasing awareness about the environment pollution protection. As a consequence, the Environmental Regulation has increased the emission limits imposing, for instance, lower concentrations at the wastewater treatment plant (WWTP) outlets. As a consequence of this fact, several WWTPs are not able to respect the emission limits and need to be upgraded. In view of such needs new technology are emerging and new WWTP solution schemes are being realized. With respects to the nutrient removal enhancing, a possible solution can be the UCT-MBR which couples the University of Cape Town scheme with a Membrane Bioreactor. In the light of such considerations, the s…

Studi pilota su sistemi MBR e MBBR.

Biological Nutrient Removal and Fouling Phenomena in a University of Cape Town Membrane Bioreactor Treating High Nitrogen Loads

The behavior of a University of Cape Town (UCT) membrane bioreactor (MBR) system was investigated for use in biological nutrient removal from real wastewater. The pilot plant was in operation for a period of 165 days, during which an extensive data gathering campaign was conducted. The pilot plant was started up by inoculating it with activated sludge from a nearby wastewater treatment plant, and it was fed by real municipal wastewater characterized by high organic nitrogen concentrations attributable to discharges from industrial wastewater and sporadic landfill leachate. Carbon and biological nutrient removal processes, a sludge production process, and a membrane fouling mechanism were an…

Modelling and dynamic simulation of hybrid moving bed biofilm reactors: model concepts and application to a pilot plant.

In the recent years, there has been an increasing interest in the development of hybrid reactors, especially in the up-grading of existing activated sludge plants that are no longer able to comply with concentration limits established by regulatory agencies. In such systems the biomass grows both as suspended flocs and as biofilm. In this way, it is possible to obtain a higher biomass concentration in the reactor, but without any significant increase of the load to the final clarifier. The paper presents the setting-up of a dynamic mathematical model aimed at quantitatively describing the biokinetic processes occurring in a hybrid moving bed biofilm reactor (HMBBR), and, more in general, in…

Un modello di simulazione per la previsione del rischio ambientale di una discarica controllata

La memoria presenta un modello matematico di simulazione messo a punto per la previsione del plume di contaminazione in falda originato da perdite attraverso l’impermeabilizzazione di fondo di una discarica controllata. Il modello è composto da: i) un sottomodello “discarica”, nel quale vengono valutate le caratteristiche quali-quantitative di produzione del percolato e delle perdite attraverso il sistema di impermeabilizzazione di fondo della discarica; ii) un sottomodello di “destino e trasporto” degli inquinanti nei terreni insaturo e saturo, in cui sono simulate le variazioni quali-quantitative del percolato infiltrato; iii) un sottomodello di valutazione del rischio sanitario nei confr…

La gestione delle risorse idriche alla luce del nuovo quadro normativo.

Start-up of a submerged membrane bioreactor with complete sludge retention.

Point and no point pollution assessment for a receiving water body quality management

Sviluppo di un Sistema Informativo Territoriale per l’analisi a scala regionale dello stato di qualità dei corpi idrici siciliani

Sequential biological and photocatalysis based treatments for shipboard slop purification: A pilot plant investigation

This study investigated the treatment of a shipboard slop containing commercial gasoline in a pilot plant scale consisting of a membrane biological reactor (MBR) and photocatalytic reactor (PCR) acting in series. The MBR contributed for approximately 70% to the overall slop purification. More precisely, the biological process was able to remove approximately 40%, on average, of the organic pollution in the slop. Nevertheless, the membrane was capable to retain a large amount of organic molecules within the system, amounting for a further 30% of the influent total organic content removal. However, this affected the membrane fouling, thus resulting in the increase of the pore blocking mechani…

COD and TPH analysis in slops experimental treatment plants: analytical problems.

COD AND TPH ANALYSIS IN SLOPS EXPERIMENTAL TREATMENT PLANTS: ANALYTICAL PROBLEMS. In the last years, the persistence and accumulation of xenobiotic compounds in the environment created many disposal problems of oily wastewater generated by ships, mainly in engine-rooms (bilge waters) and by cleaning of tanker (slops). The high salinity levels (up to 25.000 mgL-1) and the pollutants concentration, both limit the chances of discharge into the sewer systems and address the disposal of these wastewaters to the sea. For these reasons it is necessary to treat such wastewater efficiently before discharging [1]. As a part of a broader project concerning slops treatments, this work addresses issues …

Performance of a MBR pilot plant treating high strength wastewater subject to salinity increase: Analysis of biomass activity and fouling behaviour

Membrane bioreactors produce high quality effluents that could be suitable for reuse. However, when treating high strength wastewater subject to a salinity increase, a modification of biomass characteristics may occur. This circumstance is of importance, since it can have a significant impact in terms of biokinetic as well as fouling behaviour. The aim of the study was to evaluate the performance of a pilot plant MBR, in terms of biomass activity and membrane fouling, fed with high strength synthetic wastewater, when subject to a salinity increase. With normal salinity, the pilot plant showed high removal efficiencies and high biomass respiratory activity. On the other hand, the salinity in…

Destino dei radionuclidi negli impianti di depurazione delle acque reflue urbane

Lo studio presentato in questo lavoro ha avuto come obiettivo il monitoraggio e l’analisi del destino dei radionuclidi negli impianti di depurazione ed è stato condotto in collaborazione tra l’Università di Palermo e ARPA Sicilia. Esso ha previsto lo svolgimento di due fasi sperimentali. Nel corso della prima sono stati monitorati gli impianti di depurazione a servizio dei Comuni di Palermo (in località Acqua dei Corsari e Fondo Verde), Bagheria e Cefalù; nella seconda fase l’indagine è stata limitata al solo impianto di Acqua dei Corsari, nel quale si erano riscontrati in precedenza i maggiori spunti di interesse. In entrambe le fasi sono stati prelevati campioni istantanei in diverse sezi…

Aerobic granular sludge treating shipboard slop: Analysis of total petroleum hydrocarbons loading rates on performances and stability

Abstract The work focuses on the feasibility of treating slop with aerobic granular sludge. For this purpose, a 3.5 L granular sequencing batch reactor was activated and it was monitored for 156 days. The experimental campaign was divided into two periods, named Period I (100 days) and Period II (56 days). Total Petroleum Hydrocarbon (TPH) concentration in the slop was, on average, equal to 6.8 ± 1.5 mg L−1 and 13 ± 1.5 mg L−1 in Period I and Period II respectively. The obtained results during the first experimental period indicated that about 80 days were required to reach steady state with mature granules, when TPHs removal efficiency was approximately 90%. The results indicated that both…

Comparison between hybrid moving bed biofilm reactor and activated sludge system: a pilot plant experiment

The paper presents the comparison between the traditional activated sludge system (AS) and a hybrid moving bed biofilm reactor (HMBBR). In particular, an experimental campaign has been carried out at the WWTP in Palermo (Italy), on a pilot plant consisting of two pre-anoxic schemes. The aerated tank of the HMBBR line was filled with suspended carriers (AnoxKaldnes™ K1), with a 30% filling ratio. The hydraulic load of the HMBBR line was increased up to two times the AS one. Further, in order to distinguish the additional contribution of the attached biomass for the HMBBR system, in the two lines the Mixed Liquor Suspended Solids (MLSS) was maintained as equal as possible. The monitoring peri…

Identifiability analysis for receiving water body quality modelling considering a holistic approach

Treatment of high strength industrial wastewater with membrane bioreactors for water reuse: Effect of pre-treatment with aerobic granular sludge on system performance and fouling tendency

Abstract In this study, the treatment of citrus wastewater with membrane bioreactors (MBRs) under different configurations was investigated for water reuse. In particular, one MBR and one aerobic granular sludge MBR (AGS + MBR) bench scale plants were operated for 60 days. The experimental campaign was divided into two periods. In Phase I, a conventional hollow fiber MBR was employed for the treatment of the raw high strength wastewater, whereas in Phase II a combination of in-series reactors (AGS + MBR) was adopted for the treatment of the high strength citrus wastewater The results demonstrated that both plant configurations enabled very high COD removal, with average values close to 99%.…

La metodica wastewater based epidemiology come proxy di quantificazione del consumo di sostanze stupefacenti nella popolazione: l’esperienza della città di Palermo.

INTRODUZIONE Le istituzioni europee e la comunità scientifica hanno, recentemente, definito un nuovo modello di sorveglianza attiva della potenziale diffusione delle droghe nella collettività, la Wastewater Based Epidemiology (WBE), attraverso la ricerca analitica delle molecole e dei loro metaboliti nelle acque reflue cittadine. Lo scopo di questo lavoro è stato la valutazione di una preliminare applicazione di METODIca WBE nella città di Palermo, poco studiata in precedenti analisi a livello nazionale e internazionale. METODI Sono stati prelevati 28 campioni (2 litri cad) di refluo medio delle 24 ore in ingresso ai due depuratori di Palermo (WP1=45.000 ab. eq.; WP2=330.000 ab. eq.) in un …

Achievement of partial nitrification under different carbon-to-nitrogen ratio and ammonia loading rate for the co-treatment of landfill leachate with municipal wastewater

Abstract Partial nitrification (PN) is a technically and economically effective solution for the treatment of wastewater featuring low C/N ratio, allowing to achieve approximately 25% energy saving and 40% carbon source for denitrification. This study investigated the effect of different carbon to nitrogen ratio (C/N) and ammonia loading rate (ALR) on PN performances in a sequencing batch reactor (SBR) treating landfill leachate with municipal wastewater. The aim was to find an optimum range for C/N and ALR to maximize PN performances. Results demonstrated that a proper balancing between ALR and C/N is crucial to achieve high PN efficiency. The results highlighted the existence of an optimu…

CO-TREATMENT OF LANDFILL LEACHATE IN SBR SYSTEM: LAB-SCALE CASE STUDY REPORT

SUMMARY: Landfill leachate represents nowadays one of the most controversial topics in the waste management cycle. A possible alternative for treating aged landfill leachate is represented by the co-treatment with municipal wastewater (MWW) that provides the necessary amount of biodegradable substances to enhance the development of bacteria metabolism. The correct tradeoff between landfill leachate and MWW represent a key factor in order to avoid inhibition of biomass activity. The paper reports the results of an experimental research carried out on two lab-scale Sequencing Batch Reactors (SBRs) fed with synthetic wastewater and landfill leachate in different percentages (SBR1 fed with 20% …

Rainwater Reuse in Urban Areas: A Mathematical Model and a Long-Term Modelling Approach

Natural water resources are becoming increasingly limited due to global-scale climate change and water availability issues have become so severe that they must be addressed. Given these issues, reuse of wastewater and rainwater provides a promising way to cope with water shortages. This paper describes an investigation into the efficiency of rainwater usage systems. A conceptual model was built to assess the behaviour of rainwater tanks and their effectiveness in coping with water shortages. The study is based on a long-term simulation (12 years) of different rainwater reuse tank schemes. The associated reductions in residential freshwater demand (water reuse efficiency) and wet-weather run…

A model for wastewater organic removal and fouling development in a SMBR pilot plant

The paper presents the setting up of a mathematical model for membrane bioreactor able to simulate physical-biological wastewater organic removal. The model is basically divided into two sub-models: the first sub-model is basically devoted for the simulation of the biological features and the second one for the physical processes. In particular regarding the biological aspects, the ASM concept has been employed. On the other hand, the physical processes have been modelled considering the deep-bed theory taking into account not only the effect of the physical membrane filtration but also the cake layer effect. This latter operates as a biological membrane leading to a further reduction of th…

The benefit effects of rainwater utilization: a long term modelling approach

Criteri di progettazione dei bioreattori a membrana

Identifiability analysis for receiving water body quality modelling

In urban drainage, new computational possibilities have supported the development of new integrated approaches aimed at joint water quantity and quality analysis of the whole urban drainage system. Although the benefit of an integrated approach has been widely demonstrated, to date, several aspects prevent its applicability such as scarce availability of field data if compared with model complexity. These aspects sometimes prevent the correct estimation of parameters thus leading to large uncertainty in modelling response. This is a typical parameter identifiability problem that is discussed in the present paper evaluating the effect of identifiability procedures in increasing operator conf…

Uncontrolled methane emissions from a MSW landfill surface: Influence of landfill features and side slopes

Sanitary landfills for Municipal Solid Waste (MSW) disposal have been identified as one of the most important anthropogenic sources of methane (CH4) emissions; in order to minimize its negative effects on the environment, landfill gas (LFG) recovery is a suitable tool to control CH4 emissions from a landfill site; further, the measurement of CH4 emissions can represent a good way to evaluate the effectiveness of LFG recovering systems. In general, LFG will escape through any faults in the landfill capping or in the LFG collection system. Indeed, some areas of the capping can be more permeable than others (e.g. portions of a side slope), especially when considering a temporarily capped zone …

Urban water quality modelling: a parsimonious holistic approach for a complex real case study

In the past three decades, scientific research has focused on the preservation of water resources, and in particular, on the polluting impact of urban areas on natural water bodies. One approach to this research has involved the development of tools to describe the phenomena that take place on the urban catchment during both wet and dry periods. Research has demonstrated the importance of the integrated analysis of all the transformation phases that characterise the delivery and treatment of urban water pollutants from source to outfall. With this aim, numerous integrated urban drainage models have been developed to analyse the fate of pollution from urban catchments to the final receiving …

Modelli per la valutazione dell’inquinamento fluviale a scala di bacino.

Uso del nocciolino di oliva come materiale di riempimento di biotrincee per la denitrificazione biologica in situ di acque di falda

Tra le varie possibilità di intervento per la rimozione dei nitrati dalle acque di falda, notevole interesse suscita il trattamento in situ dei plume contaminati mediante la realizzazione di biotrincee denitrificanti scavate in situ e naturalmente attraversate dalle acque di falda. Tra i materiali di origine organica che sono stati testati per tali applicazioni, il nocciolino di olive è risultato uno dei più idonei alle potenziali applicazioni di pieno campo. Tale tipo di materiale possiede un elevato contenuto di carbonio organico totale, prossimo al 50%, e una percentuale di lignina prossima al 45% in peso. Il lavoro proposto riporta i risultati di una campagna sperimentale eseguita media…

Sensitivity analysis and uncertainty assessment of a SMBR model

Over the last decade new technologies are emerging even more for wastewater treatment. Among the new technologies, a recent possible solution regards membrane bioreactors (MBRs) that represent a promising alternative to conventional processes. Nowadays, the recurrence to mathematical models as reliable tools in planning as well as management issues is of growing interest in Wastewater Treatment Plants field. Regarding MBR modelling, due to the intrinsic complexity and uncertainty in some processes, basic models that can provide a holistic understanding of the technology at a fundamental level are of great necessity. Many mathematical models have been developed for modelling the MBR which ba…

Combination of the OSA process with thermal treatment at moderate temperature for excess sludge minimization

Abstract This study investigated the chance to couple the conventional Oxic Settling Anaerobic (OSA) process with a thermic treatment at moderate temperature (35 °C). The maximum excess sludge reduction rate (80%) was achieved when the plant was operated under 3 h of hydraulic retention time (HRT). Compared with the conventional OSA system, the thermic treatment enabled a further improvement in excess sludge minimization of 35%. The observed yield coefficient decreased from 0.25 gTSS gCOD−1 to 0.10 gTSS gCOD−1 when the temperature in the anaerobic reactor was increased to 35 °C, despite the lower HRT (3 h vs 6 h). Moreover, the thermic treatment enabled the decrease of filamentous bacteria,…

Micropollutants throughout an integrated urban drainage model: Sensitivity and uncertainty analysis

Abstract The paper presents the sensitivity and uncertainty analysis of an integrated urban drainage model which includes micropollutants. Specifically, a bespoke integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole – SMX). The model takes into account also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Overall, five scenarios, each characterized by different uncertainty combinations of sub-systems (i.e…

Comparison between two MBR pilot plants treating synthetic shipboard slops: effect of salinity increase on biological performance, biomass activity and fouling tendency

The paper reports the main results of an experimental campaign carried out on two bench scale pilot plants for treatment of synthetic shipboard slops. In particular, two membrane bioreactors (MBRs) with submerged configuration were analyzed. One MBR pilot plant (namely, Line A) was fed with synthetic shipboard slop and was subjected to a gradual increase of salinity. Conversely, the second MBR pilot plant (namely, Line B) was fed with the same synthetic shipboard slop but without salt addition, therefore operating as a “control” unit. Organic carbon, hydrocarbons and ammonium removal, kinetic constants, extracellular polymeric substances (EPSs) production and membranes fouling rates have be…

Hybrid moving bed biofilm reactors: a pilot plant experiment.

The growing increment of the urbanization and on the other hand, the even more strict effluent limits imposed by the Water Framework Directive for the receiving water body quality state have lead to a need of upgrading several existing WWTP. With this respect HMBBR systems are an innovative solution since allow to upgrade existing high loaded WWTP without building new tanks. However, some uncertainties in their design, maintenance as well as performance have to be addressed due to their recent acquisition compared with well consolidated technologies such as activated sludge systems. In this light, a data gathering campaign on a HMBBR pilot plant has been performed. The aim was to detect the…

Spatial diversity of chlorine residual in a drinking water distribution system: application of an integrated fuzzy logic technique

A reduction in the concentration of chlorine, which is used as a chemical disinfectant for water in drinking water distribution systems, can be considered to be an index of the progressive deterioration of water quality. In this work, attention is given to the spatial distribution of the residual chlorine in drinking water distribution systems. The criterion for grouping the water-quality parameters normally used is highly subjective and often based on data that are not correctly identified. In this paper, a cluster analysis based on fuzzy logic is applied. The advantage of the proposed procedure is that it allows a user to identify (in an automatic way and without any specific assumption) …

Biomethane Production from Anaerobic Co-Digestion of Selected Organic Fraction of Municipal Solid Waste (OFMSW) with Sewage Sludge: Effect of the Inoculum to Substrate Ratio (ISR) and Mixture Composition on Process Performances

The aim of this study was to evaluate the effect of the inoculum to substrate ratio (ISR) and the mixture ratio between organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) on the methane production potential achievable from anaerobic co-digestion (AcoD). Biochemical Methane Potential (BMP) assays at mesophilic temperature were used to determine the best AcoD configuration for maximizing methane yield and production rate, as well as to address possible synergistic effects. The maximum methane yield was observed at ISR of 1 and 60% OFMSW: 40% SS as co-digestion mixture, whereas the highest methane production rate was achieved at ISR of 2 with the same mixture ratio (207 m…

I contributi inquinanti dei sistemi di drenaggio urbano: considerazioni procedurali e tecnologiche

l'acqua è un bene

EFFETTI DELLE ACQUE DI PIOGGIA SULL’EFFICIENZA DEGLI IMPIANTI DI DEPURAZIONE

Nella memoria sono valutati gli effetti delle acque di pioggia sull’efficienza degli impianti di depurazione a servizio di centri urbani dotati di fognature a sistema unitario. In particolare, sono presentati i risultati di uno studio modellistico mirato a identificare e quantificare i maggiori fattori critici che possono avere luogo a causa del sovraccarico di un impianto di depurazione di potenzialità medio-bassa a seguito di un evento di pioggia. L’indagine è stata limitata ai trattamenti secondari dell’impianto, costituiti da una vasca a fanghi attivi seguita da un sedimentatore finale a flusso orizzontale radiale. Per tale schema di impianto sono stati presi in esame cinque diverse pot…

Study of aerobic granular sludge stability in a continuous-flow membrane bioreactor.

A granular continuous-flow membrane bioreactor with a novel hydrodynamic configuration was developed to evaluate the stability of aerobic granular sludge (AGS). Under continuous-flow operation (Period I), AGS rapidly lost their structural integrity resulting in loose and fluffy microbial aggregates in which filamentous bacteria were dominant. The intermittent feeding (Period II) allowed obtaining the succession of feast and famine conditions that favored the increase in AGS stability. Although no further breakage occurred, the formation of new granules was very limited, owing to the absence of the hydraulic selection pressure. These results noted the necessity to ensure, on the one hand the…

Sequential Batch Membrane BioReactor treating saline wastewater

A sequential batch membrane bioreactor treating high strength salinity wastewater has been investigated. The salt effects on carbon and nutrient removal, fouling behaviour as well as biomass kinetics have been analysed. Salinity was increased at step of 2 g NaCl L-1 per week. The total COD removal efficiency was high (93%) along the entire experimental campaign. However, the biological contribution on the COD removal efficiency was reduced with the increase of salinity. The lowest nitrification removal efficiency (63%) was obtained at 10 g NaCl L-1 salinity due to the lower nitrifier activity. Regarding membrane fouling, the irreversible cake deposition was the predominant fouling mechanism…

Biological nutrient removal using intermittent aeration in a hybrid moving bed biofilm reactor

The paper presents an experimental study on a lab scale pilot plant in a Hybrid Moving Bed Biofilm Reactor. The pilot plant was fed with synthetic wastewater and was in operation considering two different operating conditions: continuous aeration and intermittent aeration. Both continuous and intermittent aeration were monitored and compared in order to seek the best conditions for carbon and nitrogen removal. At the beginning of the experimentation, an initial period of about 90 days was considered during which the pilot plant worked in bench scale configuration for allowing the formation of biofilm on the carriers. Once the biofilm growth was accomplished, the pilot plant worked for a fir…

Effect of C/N shock variation on the performances of a moving bed membrane bioreactor.

Abstract The effect of a sharp variation of C/N ratio in a moving bed membrane bioreactor (MB-MBR) pilot plant treating high strength wastewater has been investigated. The experimental campaign was divided into two periods, each characterized by a different C/N ratio (namely, 2.5 and 15, Period 1 and Period 2, respectively). The MB-MBR system was analyzed in terms of organic carbon removal, nitrification efficiency, biokinetic activity and fouling behavior. The results showed that the nitrification process was severely affected by lower C/N value and by high concentration of ammonia. It was noticed an extensive stress effect on the autotrophic bacteria. Furthermore, it was observed an incre…

Biological nitrogen and phosphorus removal in membrane bioreactors: model development and parameter estimation

Membrane bioreactors (MBR) are being increasingly used for wastewater treatment. Mathematical modeling of MBR systems plays a key role in order to better explain their characteristics. Several MBR models have been presented in the literature focusing on different aspects: biological models, models which include soluble microbial products (SMP), physical models able to describe the membrane fouling and integrated models which couple the SMP models with the physical models. However, only a few integrated models have been developed which take into account the relationships between membrane fouling and biological processes. With respect to biological phosphorus removal in MBR systems, due to th…

River water quality modelling: a parsimonious model approach

A mathematical model for wastewater modification processes assessment in a stabilization reservoir

The paper presents a mathematical model for the simulation of the ecological status of a wastewater stabilization reservoir (WSR). WSRs are hypertrophic aquatic systems devoted to storage of water resources in warm countries where shortage conditions have quite often to be faced. Several factors that affect the stabilization reservoir effluent quality were taken into account: hydraulics and hydrology, solar radiation, atmospheric reaeration, algae, zooplankton, organic matter, pathogen bacteria, and sediment-water interaction. The model quantifies the specific influence of each factor on effluent quality, evaluating the correlation between the different considered factors. State variables i…

An integrated model for physical-biological wastewater organic removal in a submerged membrane bioreactor: Model development and parameter estimation

The paper presents the setting up of a mathematical model for membrane bioreactor able to simulate physical-biological wastewater organic removal. The model is basically divided into two sub-models: the first sub-model is basically devoted for the simulation of the biological features and the second one for the physical processes. In particular regarding the biological aspects, the ASM concept has been employed. On the other hand, the physical processes have been modelled considering the deep-bed theory taking into account not only the effect of the physical membrane filtration but also the cake layer effect. This latter operates as a biological membrane leading to a further reduction of th…

Characterization of Biomass Activity in Conventional and Hybrid MBR Pilot Plants by Means of Respirometric Techniques

abstract

Aerobic granular sludge treating high strength citrus wastewater: Analysis of pH and organic loading rate effect on kinetics, performance and stability.

Abstract In the present paper, the feasibility of citrus wastewater treatment with aerobic granular sludge sequencing batch reactors (AGSBR) was investigated. Two AGSBRs (named R1 and R2, respectively) were operated for 90 days under different organic loading rates (OLR) and pH in two experimental periods. The OLR ranged approximately between 3.0 kg TCOD m−3d−1 and 7 kg TCOD m−3d−1 during Period I, whereas between 7 kg TCOD m−3d−1 and 15 kg TCOD m−3d−1 during Period II. pH was maintained at 7.0 and 5.5 in R1 and R2, respectively. The results revealed that under high OLR and unbalanced feast/famine regime (Period I), the development of fast-growing microorganisms (fungi and filamentous bacte…

Radionuclides in wastewater treatment plants: monitoring of Sicilian plants.

Three Sicilian wastewater treatment plants were monitored to assess the occurrence and the behaviour of radionuclides. Two sampling campaigns (screening and long-term) were carried out during which liquid and solid samples have been analysed. It was found that 131I mostly occurred in the samples analysed during the screening campaign (43% of the analysed samples contained 131I). High 131I specific activity was found in the mixed liquor, recycled sludge and dehydrated sludge samples. This finding was mainly due to the tendency of 131I to be associated with solid particles. During the long-term sampling campaign an influence of the sludge retention time (SRT) on the 131I behaviour was found. …

Occurrence of Microplastics in Waste Sludge of Wastewater Treatment Plants: Comparison between Membrane Bioreactor (MBR) and Conventional Activated Sludge (CAS) Technologies.

In this study, the presence of microplastics in the sludge of three wastewater treatment plants (WWTPs) was examined. The investigated WWTPs operated based on a conventional activated sludge (CAS) process, with (W1) or without (W2) primary clarification, and a membrane bioreactor process (MBR) (W3). The microplastics (MPs) concentration in the samples of W3 was approximately 81.1 ± 4.2 × 103 particles/kg dry sludge, whereas MPs concentrations in W1 and W2 were 46.0 ± 14.8 × 103 particles/kg dry sludge and 36.0 ± 5.2 × 103 particles/kg dry sludge, respectively. Moreover, MPs mainly consisted of fragments (66–68%) in the CAS plants, whereas the fra…

Particle size distribution and biomass growth in a submerged membrane bioreactor

Submerged membrane bioreactors (MBR)associate in a single treatment unit a process ofbiological treatment and a phase of solid/liquidseparation by membrane filtration. Due to reduced membrane porosity, suspendedsolids and large amount of bacteria and virusesmay be retained in the reactor; consequently, highbiomass concentration is generally established inthe system. Indeed, this latter circumstance leadsto obtain a system able to operate with a low F/Mand high SRT and hence, as a result, a low sludgeproduction. In technical literature, the definition of fou-lants in MBR systems is a controversial task.More specifically, the influence of TSS onmixed liquor filterability has not been yet full…

Water quality modelling for ephemeral rivers: Model development and parameter assessment

Summary River water quality models can be valuable tools for the assessment and management of receiving water body quality. However, such water quality models require accurate model calibration in order to specify model parameters. Reliable model calibration requires an extensive array of water quality data that are generally rare and resource-intensive, both economically and in terms of human resources, to collect. In the case of small rivers, such data are scarce due to the fact that these rivers are generally considered too insignificant, from a practical and economic viewpoint, to justify the investment of such considerable time and resources. As a consequence, the literature contains v…

Analisi di processo e dinamica della comunità batterica nel trattamento di sedimenti marini con reattori bioslurry

Nella nota sono riportati i risultati di una sperimentazione condotta mediante la messa in esercizio di un reattore bioslurry per il trattamento di sedimenti marini contaminati da idrocarburi. Sono state valutate le performance di processo in termini di rimozione di TPH (86% con velocità di rimozione massima di 36 mgTPH kg-1 d-1) congiuntamente ad altre tipologie di indagini volte ad ottenere maggiori informazioni sulla natura dei processi che si sono sviluppati nel reattore. Nello specifico, è stato utilizzato un approccio di tipo microbiologico mediante l’adozione di una tecnica di sequenziamento di nuova generazione (NGS - Next Generation Sequencing). Dall’analisi dei dati biologici è st…

Uncertainty in sewer sediment deposit modelling: detailed vs simplified modelling approaches.

Abstract The paper presents the results of a study in which the uncertainty levels associated with a detailed and a simplified/parsimonious sewer sediment modelling approach have been compared. The detailed approach used an Infoworks CS sewer network model combined with a user developed sediment transport code and the simplified approach used a conceptual sewer flow and quality model. The two approaches have been applied to a single case study sewer network and the simulation results compared. The case study was selected as moderate storm events had occurred during a 2 year rainfall and sewer flow monitoring period. Flooding had been observed and this was thought to be caused by significant…

Modelling hydrology and water quality in a Mediterranean catchment

In this study the SWAT model has been used in order to analyse and quantify pollution dynamics at basin scale depending on concentrated and diffuse sources. Nowadays, the receiving water bodies quality safeguarding is of growing importance due to the promulgation of recent laws as well as the growing sensitivity regarding the environment issues by the scientific and practitioner committee. Recently the EU 2000/60 (Water Framework Directive) makes the analysis of receiving water bodies even more complex by integrating the pollution in urban areas in a framework of the pollution sources at catchment scale. and making necessary further integration of environmental impacts associated with disch…

Sensitivity and uncertainty analysis of an integrated ASM2d MBR model for wastewater treatment

Abstract An integrated membrane bioreactor (MBR) model was previously proposed and tested. The model provides a comprehensive and detailed description of the nitrogen biological removal processes with respect to up-to-date literature. This paper presents a sensitivity and uncertainty analysis aimed at identifying the key factors affecting the variability of the model predictions. The Standardized Regression Coefficients (SRC) method was adopted for the sensitivity analysis. The uncertainty analysis was employed by running Monte Carlo simulations by varying only the value of the key factors affecting the model outputs. The sensitivity analysis combined with the uncertainty analysis applied h…

Greenhouse gas emissions from integrated solid waste management: a new mathematical model

Municipal solid waste management significantly contributes to the emission in the atmosphere of greenhouse gases (e.g. CO2, CH4, N2O) and therefore the management process from collection to treatment and disposal has to be optimized in order to reduce these emissions. Many literature models developed for the evaluation of greenhouses gases emissions from the waste management system are based on the analysis of the life cycle. These models are not optimized for evaluation of emissions. The aim of this study is to overcome these limitations by proposing a mathematical model to estimate greenhouse gas emissions resulting from the integrated waste management. The model is aimed to be a verifica…

WATER QUALITY ANALYSIS OF A WATER DISTRIBUTION SYSTEM: A CASE STUDY

Uncertainty in urban stormwater quality modelling: The influence of likelihood measure formulation in the GLUE methodology

In the last years, the attention on integrated analysis of sewer networks, wastewater treatment plants and receiving waters has been growing. However, the common lack of data in the urban water-quality field and the incomplete knowledge regarding the interpretation of the main phenomena taking part in integrated urban water systems draw attention to the necessity of evaluating the reliability of model results. Uncertainty analysis can provide useful hints and information regarding the best model approach to be used by assessing its degrees of significance and reliability. Few studies deal with uncertainty assessment in the integrated urban-drainage field. In order to fill this gap, there ha…

The influence of solid retention time on IFAS-MBR systems: analysis of system behavior.

A University of Cape Town Integrated Fixed-Film Activated Sludge Membrane Bioreactor (UCT-IFAS-MBR) pilot plant was operated at different values of the sludge retention time (SRT). Three SRTs were investigated at different durations: indefinitely, 30 and 15 days. The organic carbon, nitrogen and phosphorus removal, kinetic/stoichiometric parameters, membrane fouling tendency and sludge filtration properties were assessed. The findings showed that by decreasing the SRT, the pilot plant could maintain excellent carbon removal efficiencies throughout the experiments. In contrast, the biological carbon removal showed a slight nitrification and was slightly affected by the decrease of the SRT, s…

TREATMENT OF LANDFILL LEACHATE IN SBR SYSTEMS: ANALYSIS OF BIOMASS ACTIVITY BY MEANS OF RESPIROMETRIC TECHNIQUES

In the last decades landfilling has been the main method of municipal solid waste (MSW) disposal in many countries. MSW landfills are usually considered as a large biological reactor where the MSWs undergo anaerobic digestion producing gas and liquid emissions. Aged, or mature leachate, which is produced by older landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of co-treatment of landfill leachate and synthetic wastewater in different percentages, in terms of process performance and biomass activity, by means of respirometric tec…

Analisi di incertezza nella risposta quali-quantitativa a scala giornaliera di un bacino naturale

MUNICIPAL WASTEWATER TREATMENT IN A HYBRID ACTIVATED SLUDGE BIOFILM REACTOR: A PILOT PLANT EXPERIENCE

A hybrid activated sludge/biofilm process (IFAS) was investigated. This process which contains both suspended and attached biomass, is created by introducing plastic elements as biofilm carriers material into a classical activated sludge system. This process is suitable for upgrading existing activated sludge wastewater treatment plants which are no longer able to comply with the effluent standards, and in particular in those cases where the existing plant does not nitrify or only nitrify during summer. However, the IFAS processes are relatively new and there are still uncertainties with respect to their design. A main task is to find a rational approach to the design of nitrification in hy…

A QUANTITY-QUALITY MATHEMATICAL MODEL FOR MUNICIPAL SOLID WASTE LANDFILL: MODEL CALIBRATION AND SENSITIVITY ANALYSIS

Landfill leachate represents nowadays one of the most important issue related to the waste management cycle. Knowledge about leachate distribution and transport as well as fate of pollutants is fundamental for understanding the behavior of the landfill reactor. In the present study, a simple 1-D mathematical model was developed for the simulation of the vertical leachate fluxes throughout a landfill for MSW as well as the fate of inorganic pollutants within the landfill leachate pathway. The model was based on mass balance equations, which allowed to evaluate the moisture accumulation inside the landfill body as well as contaminant transport processes. The model enables to calculate the moi…

Respirometric assessment of heterotrophic and autotrophic biomass activity in alternate oxic-anoxic MBR pilot plant

The paper reports the main results of an experimental study carried out on a Membrane Biological Reactor (MBR) pilot plant characterized by intermittent aeration. The effect of different aeration/non aeration ratio (TA/TNA) on biomass behavior, in terms of heterotrophic and autotrophic kinetic parameters and active biomass fraction, was studied. Moreover was proposed a method to evaluate the autotrophic active fraction, derived by a combination of the ASM1 model and biokinetic parameters directly evaluated by means of respirometry. The experimental observation outlined that TA/TNA in the cycle didn’t affect heterotrophic biomass kinetic and active fraction. This one instead, resulted strong…

Sequential batch membrane bio-reactor for wastewater treatment: The effect of increased salinity

In this work, a sequential batch membrane bioreactor pilot plant is investigated to analyze the effect of a gradual increase in salinity on carbon and nutrient removal, membrane fouling and biomass kinetic parameters. The salinity was increased by 2 g NaCl L-1 per week up to 10 g NaCl L-1. The total COD removal efficiency was quite high (93%) throughout the experiment. A gradual biomass acclimation to the salinity level was observed during the experiment, highlighting the good recovery capabilities of the system. Nitrification was also influenced by the increase in salinity, with a slight decrease in nitrification efficiency (the lowest value was obtained at 10 g NaCl L-1 due to lower nitri…

Comparison between two MBR pilot plants treating synthetic shipboard slops: effect of salinity increase on biological performance, biomass activity and fouling tendency

The paper reports the main results of an experimental campaign carried out on two bench scale pilot plants for the treatment of synthetic shipboard slops. In particular, two membrane bioreactors (MBRs) with submerged configuration were analyzed. One MBR pilot plant (namely, Line A) was fed with synthetic shipboard slop and was subjected to a gradual increase of salinity. Conversely, the second MBR pilot plant (namely, Line B) was fed with the same synthetic shipboard slop but without salt addition, therefore operating as a “control” unit. Organic carbon, hydrocarbons and ammonium removal, kinetic constants, extracellular polymeric substances (EPSs) production and membranes fouling rates…

Simulation of the operation of detention tanks.

The performance of detention tanks with different characteristics (volume, on-line and off-line arrangement) has been evaluated according to the results of a continuous simulation. The conceptual simplified model for sewer system simulation (COSMOSS) model has been used to simulate the operation of the tanks. The differences between the performance of on-line and off-line tanks and the influence of the characteristics of different catchments have been examined. According to the results of the simulations detention tanks demonstrated good performances in total suspended solids retention and this evenience can certainly help to prevent water pollution of receiving water bodies in urban areas,…

Effect of a co-substrate supply in a MBR treating shipboard slop: Analysis of hydrocarbon removal, biomass activity and membrane fouling tendency

The paper reports the main results of an experiment carried out on a membrane bioreactor (MBR) plant designed for the treatment of shipboard slops. With a view of a co-treatment process of the slop with other wastewaters, sodium acetate, as external co-substrate, was supplied (high dosage – Period 1, low dosage – Period 2) to evaluate its effects on hydrocarbons removal. The MBR pilot plant enabled approximately 99% of total petroleum hydrocarbon (TPH) removal during the entire experiment, confirming the robustness of the MBR technology for the treatment of slops. The chromatography/mass spectrometry analysis showed that the removal efficiency for each alkane was close to the value observed…

The fouling phenomenon in membrane bioreactors: assessment of different strategies for energy saving

Membrane fouling represents one of the major limiting issue for membrane bioreactor (MBR) in the wastewater treatment field. Membrane fouling and high aeration requirement (for inducing shear stress to limit fouling) in MBR systems make the operation of such systems economically demanding due to high energetic costs. Despite several studies on MBR fouling have been performed a comprehensive knowledge on how to reduce membrane fouling and consequently energy saving is still lacking and controversial. The aim of this study is to gain insights on the optimization of the operating conditions in an MBR system. In particular, the influence of the aeration intensity and the durations of filtration…

Biokinetic Behaviour of Autochthonous Halophilic Biomass at Different Salinity: Comparison Between Activated Sludge and Granular Sludge Systems

The main goal of this study was the evaluation of the impact of increasing salinity on halophilic biomass in forms of flocculent and granular sludge for the treatment of hypersaline fish-canning wastewater, focusing on the metabolic behavior of autotrophic biomass. For this purpose, two sequencing batch reactors, one with aerobic granular sludge (GSBR) and the other with flocculent activated sludge (SBR) were monitored. In both reactors, a halophilic biomass was cultivated from a real saline wastewater collected from a fish-canning industry. The salt concentration was stepwise increased (2 gNaCl L-1) from 30 gNaCl L-1 to 50 gNaCl L-1. Therefore, ammonia and nitrite uptake rates for granular…

Modelling the changes in time of MSW properties in a landfill.

Valutazione dell'inquinamento diffuso in corsi d'acqua a carattere torrentizio

Global sensitivity analysis for urban water quality modelling: comparison of different methods

Sensitivity analysis represents an important step in improving the understanding and use of environmental models. Indeed, by means of global sensitivity analysis (GSA), modellers may identify both important (factor prioritization) and non-influential (factor fixing) model input factors. However, despite the potentialities of GSA methods, only few applications have been published in the field of urban drainage modelling. In order to fill this gap this paper presents a comparison among three GSA methods (SRC, Extended-FAST and Morris screening) on an urban drainage storm-water model. In particular, an exhaustive discussion on their peculiarities, applicability, and reliability is presented. S…

Membrane bioreactors for treatment of saline wastewater contaminated by hydrocarbons (diesel fuel): An experimental pilot plant case study

Abstract The paper reports the main results of an experimental campaign performed on a membrane bioreactor pilot plant designed to treat synthetic shipboard slops. The experimental campaign was divided into two phases: salinity acclimation up to 20 g NaCl L −1 (Phase I) and hydrocarbon (diesel fuel) dosing (Phase II). The observed results show that the carbon removal was not severely affected by the wastewater features. Conversely, respirometric tests showed that nitrification was strongly affected by the salinity (33% of nitrification efficiency at 20 g NaCl L −1 – Phase I) as a result of the salinity in the autotrophic biomass. Moreover, the sludge viscosity increased during Phase II due …

Test in colonna per la denitrificazione delle acque di falda: studio del comportamento di tre differenti substrati organici

Il crescente impiego di fertilizzanti contenenti azoto ha avuto come effetto l'accumulo di nitrati nelle acque di falda. A causa della natura diffusa delle sorgenti di contaminazione, la necessità di individuare interventi di risanamento a basso costo e che richiedano attività gestionali ridotte è diventata prioritaria. In tale ottica, notevole interesse hanno recentemente riscosso i trattamenti biologici in situ, in grado di promuovere le denitrificazione delle acque di falda mediante la realizzazione di biobarriere. Nella nota vengono riportati i risultati di una ricerca sul processo di denitrificazione eterotrofa promosso utilizzando come fonte di carbonio tre materiali convenzionalmente…

The effect of hydrocarbon on a pilot plant membrane bioreactor system

The paper reports the main results from an experimental gathering campaign carried out on a bench scale plant for the evaluation of hydrocarbon effect on the system performance. In particular, a membrane bioreactor (MBR) under submerged configuration was analysed. The MBR plant was fed with synthetic wastewater containing hydrocarbons. Organic carbon, hydrocarbons and ammonium removal, kinetic constants, extracellular polymeric substances (EPSs) production and membranes fouling rates have been assessed. The observed results highlighted good system performance in terms of both COD removal and nitrification, thus showing a sort of biomass adaptation to hydrocarbon. Such a result has been also…

INCIDENZA SULL’ANALISI DI RISCHIO DELLE MODALITÁ DI MISURA DEI SOIL GAS: IL CASO DI UN S.I.N. SICILIANO

Il monitoraggio delle matrici aeriformi sta assumendo importanza crescente nell’ambito dei procedimenti di bonifica di siti contaminati, con riferimento sia all’esecuzione delle analisi di rischio, sia alla conseguente progettazione degli interventi di risanamento. L’utilizzo di misure dirette di campo si rivela di notevole interesse per la verifica di quelle indirette, ottenute con gli algoritmi implementati nei modelli matematici utilizzati per l’analisi di rischio. Obiettivo del lavoro presentato nella nota è stato quello di valutare l’influenza di misure dirette di soil gas e di flussi emissivi sull’analisi di rischio sanitaria. Come caso studio, si è considerato un S.I.N. nel territori…

Sistemi localizzati di riuso delle acque meteoriche in ambito urbano

Optimization of acetate production from citrus wastewater fermentation

Abstract Citrus wastewater is a sugar-rich waste stream suitable for the recovery of energy of material from its treatment. In this study, fermentation of citrus wastewater was carried out to assess the optimal conditions to maximize the bioconversion of the organic substrate into acetate. Unbalanced nutrient (C: N: P 200:0.1:0.1) enabled the highest acetate production. The presence of the particulate organic fraction enabled to obtain a higher acetate concentration regardless the initial COD concentration. Initial pH values higher than 5 did not cause substantial differences on the maximum bioconversion of COD into acetate in Trial 3, whereas pH lower than 5 hindered the hydrolysis process…

Sensitivity and uncertainty analysis of an integrated membrane bioreactor model

Sensitivity and uncertainty analysis, although can be of primarily importance in mathematical modelling approaches, are scarcely applied in the field of membrane bioreactor (MBR). An integrated mathematical model for MBR is applied with the final aim to pin down sources of uncertainty in MBR modelling. The uncertainty analysis has been performed combining global sensitivity analysis (GSA) with the generalized likelihood uncertainty estimation (GLUE). The model and methodology were applied to a University Cape Town pilot plant. Results show that the complexity of the modelled processes and the propagation effect from the influent to the effluent increase the uncertainty of the model predicti…

Fate of aerobic granular sludge in the long-term: The role of EPSs on the clogging of granular sludge porosity

This work aims to investigate the stability of aerobic granular sludge in the long term, focusing on the clogging of the granular sludge porosity exerted by the extracellular polymeric substances (EPSs). The effects of different cycle lengths (short and long-term cycle) on the granular sludge stability were investigated. Results obtained outlined that during the short duration cycle, the formation and breakage of the aerobic granules were continuously observed. During this period, the excess of EPS production contributed to the clogging of the granules porosity, causing their breakage in the long run. During the long-duration cycle, the extended famine period entailed a greater EPSs consump…

Global sensitivity analysis in integrated water quality modelling: an application to a real case study

The increasing sensitivity towards water quality environmental issues led to the setting up of water quality integrated modelling approaches and the definition of water quality criteria that better represent the receiving water body quality status. More specifically, compared to the past, the tendency today is to design and manage the whole integrated urban drainage system, i.e. , wastewater treatment plant and receiving water body (RWB) considering each component not separately but jointly. Despite the advantages of a holistic approach for the assessment of the RWB quality state there are some limits that may prevent a straightforward application. Indeed, integrated models are generally ch…

In sewer processes: mathematical model development and sensitivity analysis

Equifinality and uncertainty of the quali-quantitative response of a natural catchment

The effect of rainfall temporal resolution on urban drainage water quality modelling

Primi risultati sul trattamento delle acque meteoriche nella stazione sperimentale di San Giovanni in Persiceto.

Le acque di origine meteorica che si raccolgono sulle superfici delle aree urbanizzate possono contenere numerose sostanze inquinanti, in concentrazioni anche affatto trascurabili. La prima fonte di inquinanti è già individuabile nell’atmosfera dilavata dalle precipitazioni; ulteriori fonti sono costituite dal traffico stradale, dagli impianti di combustione e, infine, dalle superfici delle strade e dei tetti, tanto per il dilavamento dei depositi che su questi si accumulano in tempo secco, quanto per l’erosione dei materiali da cui essi sono costituiti. Negli Stati Uniti ed in alcuni Paesi del Nord Europa, una soluzione sempre più diffusamente applicata al problema dello smaltimento delle …

Il destino dei microinquinanti negli impianti di depurazione e nei corpi idrici.

• Monitoraggio di droghe in quattro impianti di depurazione siciliani e in un corpo idrico ricettore. • Elevata presenza nei reflui influenti a tutti gli impianti monitorati di THC-COOH e BEG, metaboliti rispettivamente della cannabis e della cocaina. • Fenomeni di degradazione naturale ad opera del biota e/o di accumulo nei sedimenti del corpo idrico ricettore comportano la riduzione delle concentrazione di THC-COOH.

Multiregression Analysis of the Kinetic Constants in Ephemeral Rivers: The Case Study of the Oreto River

Profuse efforts have been committed to develop efficient tools to measure the ecological status of the receiving water body quality state. The recurrence to mathematical models as support tools for the receiving water body quality assessment can be an optimal choice. Indeed, mathematical models can allow to build-up the cause effect relationship between polluting sources and receiving water quality. Regarding the river water quality modelling, two different kinds of river can be single out: large and small rivers. In the modelling approach, the main differences between the two types of river are reflected in the model kinetic constants. Indeed, the main quality processes which control and g…

Preliminary insights about the treatment of contaminated marine sediments by means of bioslurry reactor: Process evaluation and microbiological characterization

Abstract Contaminated marine sediments represent a critical threat towards human health and ecosystems, since they constitute a potential reservoir of toxic compounds release. In the present study, a bioslurry reactor was studied for the treatment of real marine sediments contaminated by petroleum hydrocarbons. The experimental campaign was divided in two periods: in the first period, microcosm trials were carried out to achieve useful indicators for biological hydrocarbon removal from sediments. The microcosm trials highlighted that the inoculum of halotolerant allochthonous bacteria provided the highest performance followed by autochthonous biomass. Based on the achieved results, in the s…

Quantification of diffuse and concentrated pollutant loads at the watershed-scale: an Italian case study

In this study, diffuse and point source pollutant loads were evaluated using an Italian case study: the Nocella catchment, which has been subject to extensive monitoring. The Nocella catchment is located in Sicily (Italy) and has an area of about 60 km2. The river receives wastewater and stormwater from two urban areas drained by combined sewers. The two sewer systems, two wastewater treatment plants and a river reach were monitored during both dry and wet weather periods. Thereafter, an integrated catchment-scale model was applied to simulate point pollutant sources, i.e., pollution coming from the urban drainage system, and nonpoint pollutant sources, i.e., pollution coming from agricultu…

A hydrodynamic water quality model for propagation of pollutants in rivers.

Numerical modelling can be a useful tool to assess a receiving water body's quality state. Indeed, the use of mathematical models in river water quality management has become a common practice to show the cause-effect relationship between emissions and water body quality and to design as well as assess the effectiveness of mitigation measures. In the present study, a hydrodynamic river water quality model is presented. The model consists of a quantity and a quality sub-model. The quantity sub-model is based on the Saint Venant equations. The solution of the Saint Venant equations is obtained by means of an explicit scheme based on space-time conservation. The method considers the unificatio…

The management of sewage sludge: technologies, critical issue and perspectives

The management of sludge produced by urban wastewater treatment plants has long been a problem for plant managers. This is due both to the growing costs for their disposal, and to the possible consequences that incorrect management may have on the performance of the wastewater treatment plant and on the environment. Further difficulties arose following the evolution of the European and national legislations, which regulates the management of sludge and its possible agronomic uses that introduced further checks and restrictions for this use. Several studies have been underway since last decades to reduce the extent of the problem. These focus on alternative objectives being aimed on the one …

High salinity wastewater treatment by membrane bioreactors

Abstract This chapter reviews the state of the art regarding the use of membrane bioreactor (MBR) systems for saline wastewater treatment. In particular, a comprehensive review is presented discussing the most adopted MBR configurations for the treatment of saline wastewater. Further, the chapter discusses the main effects of salinity on the biological performance, kinetic parameters, fouling development, sludge rheological features, and greenhouse gas (GHG) production. Literature results show that there is a significant effect of the salinity (and/or salinity variations) on the biological performance and membrane filtration. Specifically, it was found that a gradual salinity increase, carr…

Receiving water body quality assessment: an integrated mathematical approach applied to an Italian case study

This study presents a basin-scale approach to the analysis of receiving water body quality considering both point and non-point pollution sources. In particular, this paper describes an extensive data gathering campaign carried out in the Nocella catchment, which is an agricultural and semi-urbanised basin located in Sicily, Italy. Two sewer systems, two wastewater treatment plants and a river reach were monitored during both dry and wet weather periods. A mathematical model of the entire integrated system was also created. Specifically, a detailed modelling approach was developed by employing three well known models: Storm Water Management Model, GPS-X and Soil and Water Assessment Tool. T…

Mathematical Modelling of In-sewer Processes as a Tool for Sewer System Design

The objective of this paper is to evaluate the potential impact of in-sewer processes (COD components transformation and hydrogen sulphide production) on the design of sewer systems. The tool used for such analysis is a mathematical model derived from the WATS model (Wastewater Aerobic/anaerobic Transformation in Sewers) able to describe the processes occurring in the sewer system both under aerobic and anaerobic conditions. The model is applied to three synthetic catchments with, respectively, 10,000, 50,000 and 250,000 inhabitants connected to gravity sewer systems different in terms of type (separate or combined), slope, length, travel time, wastewater temperature. The simulation results…

Analisi integrata della qualità dei deflussi meteorici in un bacino naturale parzialmente urbanizzato

Catchment-scale modelling approach for a holistic urban water quality management

La denitrificazione biologica delle acque di falda: studio di tre differenti substrati organici

L’uso massiccio di fertilizzanti contenenti azoto è causa dei fenomeni di inquinamento diffuso delle acque di falda. In tale ottica, notevole interesse hanno recentemente riscosso i trattamenti biologici in situ, in grado di promuovere la denitrificazione delle acque di falda mediante la realizzazione di interventi che coniugano efficacia di rimozione e costi relativamente contenuti. Nella nota si riportano i risultati di una ricerca sul processo di denitrificazione eterotrofa, condotta utilizzando come fonte di carbonio tre materiali convenzionalmente considerati di scarto: corteccia di pino, sughero e sansa di olive. Lo studio è stato suddiviso in due fasi: la prima condotta in modalità b…

Modeling of perched leachate zone formation in municipal solid waste landfills.

The paper presents a 1D mathematical model for the simulation of the percolation fluxes throughout a landfill for municipal solid waste (MSW). Specifically, the model was based on mass balance equations, that enable simulation of the formation of perched leachate zones in a landfill for MSW. The model considers the landfill divided in several layers evaluating the inflow to and outflow from each layer as well as the continuous moisture distribution. The infiltration flow was evaluated by means of the Darcy’s law for an unsaturated porous medium, while the moisture distribution evaluation has been carried out on the basis of the theory of the vertically distributed unsaturated flow. The solu…

Wastewater reuse effect on soil hydraulics characteristics

A parsimonious dynamic model for river water quality assessment

Water quality modelling is of crucial importance for the assessment of physical, chemical, and biological changes in water bodies. Mathematical approaches to water modelling have become more prevalent over recent years. Different model types ranging from detailed physical models to simplified conceptual models are available. Actually, a possible middle ground between detailed and simplified models may be parsimonious models that represent the simplest approach that fits the application. The appropriate modelling approach depends on the research goal as well as on data available for correct model application. When there is inadequate data, it is mandatory to focus on a simple river water qua…

Evaluation of methane emissions from Palermo municipal landfill: Comparison between field measurements and models

Methane (CH(4)) diffuse emissions from Municipal Solid Waste (MSW) landfills represent one of the most important anthropogenic sources of greenhouse gas. CH(4) is produced by anaerobic biodegradation of organic matter in landfilled MSW and constitutes a major component of landfill gas (LFG). Gas recovery is a suitable method to effectively control CH(4) emissions from landfill sites and the quantification of CH(4) emissions represents a good tool to evaluate the effectiveness of a gas recovery system in reducing LFG emissions. In particular, LFG emissions can indirectly be evaluated from mass balance equations between LFG production, recovery and oxidation in the landfill, as well as by a d…

Integrated production of biopolymers with industrial wastewater treatment: Effects of OLR on process yields, biopolymers characteristics and mixed microbial community enrichment

The production of polyhydroxyalkanoates (PHA) using industrial wastewaters as feedstocks is a current and challenging topic. This study investigated the production of biopolymers by a mixed microbial culture under different OLRs equal to 1 kgCOD m-3d-1 (Period 1), 2 kgCOD m-3d-1 (Period 2) and 3 kgCOD m-3d-1 (Period 3). The maximum PHA content was achieved in Period 2 (0.38 gPHA gTSS-1), whereas lower values were obtained in Period 1 (0.13 gPHA gTSS-1) and Period 3 (0.26 gPHA gTSS-1). Overall, the maximum PHA productivity resulted equal to 0.08 gPHA L-1h-1 (P2), 0.05 gPHA L-1h-1 (P1) and 0.04 gPHA L-1h-1 (P3), respectively. The molecular weight of the PHA increased from Period 1 (250 kDa) t…

Shortcut nitrification-denitrification by means of autochthonous halophilic biomass in an SBR treating fish-canning wastewater

Abstract Autochthonous halophilic biomass was cultivated in a sequencing batch reactor (SBR) aimed at analyzing the potential use of autochthonous halophilic activated sludge in treating saline industrial wastewater. Despite the high salt concentration (30 g NaCl L −1 ), biological oxygen demand (BOD) and total suspended solids (TSS), removal efficiencies were higher than 90%. More than 95% of the nitrogen was removed via a shortcut nitrification-denitrification process. Both the autotrophic and heterotrophic biomass samples exhibited high biological activity. The use of autochthonous halophilic biomass led to high-quality effluent and helped to manage the issues related to nitrogen removal…

Biological minimization of excess sludge in a membrane bioreactor: Effect of plant configuration on sludge production, nutrient removal efficiency and membrane fouling tendency.

Abstract Excess sludge minimization was studied in a MBR with pre-denitrification scheme. Sludge minimization, nitrogen removal performance and membrane fouling tendency were investigated in two configurations, characterized by a different position of the sludge retention reactor (SRR). In particular, the SRR was placed: i) in the return activated sludge line (Anaerobic Side-Stream Reactor – ASSR configuration) and ii) in the mainstream between the anoxic and aerobic reactor (Anaerobic Main-Stream Reactor – AMSR configuration). The achieved results demonstrated that the ASSR enabled a higher excess sludge reduction (74% vs 32%), while achieving lower biological nitrogen removal (BNR) (TN = …

Co-treatment of landfill leachate in laboratory-scale sequencing batch reactors: analysis of system performance and biomass activity by means of respirometric techniques

Aged or mature leachate, produced by old landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of leachate co-treatment with synthetic wastewater, in terms of process performance and biomass activity, by means of respirometric techniques. Two sequencing batch reactors (SBRs), named SBR1 and SBR2, were fed with synthetic wastewater and two different percentages of landfill leachate (respectively 10% and 50% v v−1 in SBR1 and SBR2). The results showed good chemical oxygen demand (COD) removal efficiency for both reactors, with average C…

Influenza della copertura superficiale sulle emissioni diffuse di metano da discarica: analisi di casi studio

La quantizzazione delle emissioni di CH4 da discariche rappresenta un tema di rilievo nella gestione dei rifiuti. La capacità emissiva delle discariche, direttamente correlata alla decomposizione anaerobica della sostanza organica in esse smaltita, può durare per decine di anni sebbene la massima produzione di biogas si registra nei primi anni seguenti l’abbancamento dei rifiuti. Nella nota si riferisce dei risultati di alcune campagne di misura eseguite su discariche controllate per rifiuti urbani, dotate di differente tipo di copertura; in particolare, la prima discarica è dotata di capping definitivo, la seconda di capping temporaneo. I risultati ottenuti hanno evidenziato una significat…

Application of respirometric techniques for the characterization of the wastewater treated in the “Acqua dei Corsari” treatment plant of Palermo

Upgrading of an existing WWTP with Hybrid Moving Bed Biofilm Reactor systems

Applicazione del modello SWAT a un bacino siciliano fortemente antropizzato.

Metodo di calibrazione per la misura del contenuto d’acqua di un suolo mediante tecnica TDR

Stima del fenomeno del foaming nei sistemi a fanghi attivi

Assessment of landfill leachate biodegradability and treatability by means of allochthonous and autochthonous biomasses

Abstract The biodegradability and treatability of a young (3 years old) municipal landfill leachate was evaluated by means of chemical oxygen demand (COD) fractionation tests, based on respirometric techniques. The tests were performed using two different biomasses: one cultivated from the raw leachate (autochthonous biomass) and the other collected from a conventional municipal wastewater treatment plant after its acclimation to leachate (allochthonous biomass). The long term performances of the two biomasses were also studied. The results demonstrated that the amount of biodegradable COD in the leachate was strictly dependent on the biomass that was used to perform the fractionation tests…

Performance of a hybrid activated sludge/biofilm process for wastewater treatment in a cold climate region: Influence of operating conditions

a b s t r a c t The main aim of the study was to investigate a hybrid MBBR process, mostly in terms of organic matter removal and nitrification, when operating with different values of the mixed liquor sludge retention time (SRT), and highlighting the influence of temperature on the process. Based on experience in practice it was hypothesized that nitrification could be maintained at far lower SRT's than in conventional activated sludge systems and with high organic loading rates applied. A field gathering campaign has been carried out on a hybrid activated sludge/biofilm. The obtained results highlighted that the pilot plant was capable to remove the organic matter at loading rates up to 3…

An urban drainage stormwater quality model: model development and uncertainty quantification

Summary The evaluation of urban stormwater quality is of relevant importance for urban drainage, and mathematical models may be of great interest in this respect. To date, several detailed mathematical models are available to predict stormwater quantity–quality characteristics in urban drainage systems. However, only a few models take sewer sediments into account, considering their cohesive-like properties that influence the build-up process of the pollutant load. Furthermore, the model data requirements, especially for the quality aspects, are extensive, which limit their applicability and affect model results with large uncertainty. Uncertainty analysis provides a measure or index regardi…

VALUTAZIONE DEI CARICHI INQUINANTI DI ORIGINE DIFFUSA E CONCENTRATA A SCALA DI BACINO: APPLICAZIONE A UN CASO DI STUDIO SICILIANO

Obiettivo della ricerca è stata la predisposizione di un modello di tipo integrato a scala di bacino al fine di ricostruire la dinamica dei carichi inquinanti concentrati di origine civile e produttiva e dei carichi diffusi di origine agricola e zootecnica, in osservanza dei nuovi criteri di gestione dei corpi idrici superficiali introdotti dalle normative nazionale ed europea (Direttiva UE 2000/60, D.lgs. 152/2006). Il modello messo a punto è stato applicato al bacino del fiume Nocella, ubicato in Sicilia e ritenuto un idoneo banco di prova in quanto recapito di numerosi scarichi in forma concentrata e diffusa. I primi derivano in modo continuo dagli impianti di depurazione a servizio di d…

RIMOZIONE COMBINATA DI CARBONIO E NUTRIENTI IN DUE REATTORI SBR GRANULARI: EFFETTO DELLA DIMENSIONE DEI GRANULI

Sono state investigate le performance di due impianti SBR (Sequencing Batch Reactor), alimentati con refluo sintetico a base di acetato di sodio e funzionanti con due differenti tipi di fango aerobico granulare, in termini di dimensione media dei granuli. In particolare, è stato analizzato l’impatto della differente dimensione dei granuli sul processo di nitrificazione e denitrificazione simultanea (Simultaneous Nitrification Denitrification, SND) e sulla rimozione biologica del fosforo. Allo scopo di valutare l’efficienza di tale tipo di processo, sono state applicate differenti strategie di coltivazione e condizioni operative, in termini di carico organico (COD 600-1200 mg/L) e azoto (60-…

Biostabilization and biodrying of municipal solid waste.

Illicit drugs consumption evaluation by wastewater-based epidemiology in the urban area of Palermo city (Italy)

Introduction. A wastewater-based epidemiology approach was performed to estimate the drug consumption in Palermo city, the fifth largest city of Italy with a population of 671 696 inhabitants, and to investigate the monthly variability of drug loads in wastewater from different areas of the city. A seven-months detection campaign was conducted at the two wastewater treatment plants of the city. Methods. Following a pre-treatment, 32 samples of wastewater were analyzed by liquid chromatography-tandem mass spectrometry. Results. We estimated a mean cocaine use in Palermo of 0.19 g/day/1000 people, corresponding to 1.90 doses/1000 people and cannabinoids use of 2.85 g/day/1000 people, correspo…

Receiving water quality assessment: comparison between simplified and detailed integrated urban modelling approaches

Urban water quality management often requires use of numerical models allowing the evaluation of the cause–effect relationship between the input(s) (i.e. rainfall, pollutant concentrations on catchment surface and in sewer system) and the resulting water quality response. The conventional approach to the system (i.e. sewer system, wastewater treatment plant and receiving water body), considering each component separately, does not enable optimisation of the whole system. However, recent gains in understanding and modelling make it possible to represent the system as a whole and optimise its overall performance. Indeed, integrated urban drainage modelling is of growing interest for tools to …

Urban runoff modelling uncertainty: Comparison among Bayesian and pseudo-Bayesian methods

Urban stormwater quality modelling plays a central role in evaluation of the quality of the receiving water body. However, the complexity of the physical processes that must be simulated and the limited amount of data available for calibration may lead to high uncertainty in the model results. This study was conducted to assess modelling uncertainty associated with catchment surface pollution evaluation. Eight models were compared based on the results of a case study in which there was limited data available for calibration. Uncertainty analysis was then conducted using three different methods: the Bayesian Monte Carlo method, the GLUE pseudo-Bayesian method and the GLUE method revised by m…

Performance of a MBR pilot plant treating high strenght wastewater: analysis of biomass activity and fouling behaviour

Nowadays, due to the increasing awareness about environmental impact of discharges, it is necessary to realize biological processes that allow complete treatment of wastewater, able to produce high quality effluents that could be used for recycling and reuse purpose. A possible solution to cope with this issue is represented by membrane bioreactors (MBRs), which are combined systems including a bioreactor and a filtration unit. However, in presence of high strenght domestic or industrial wastewater, a modification in biomass kinetics as well as in sludge characteristics may occur. This situation is of importance, since microbial community characteristics can play an important role in membra…

Posa e recupero di cavi sottomarini per telecomunicazioni: energia e materiali in gioco.

Undersea cables for telecommunications are put out after 20 to 25 years of service in order to be replaced by new type ones that can yield a better service. As a rule, decommissioned cables are retrieved for the part stretching from the shoreline to the line (-30 m). This operation is useful from the environmental standpoint, as at the price of an energy expenditure of about 3 MJ/m an amount of materials having embodied energy as high as 72 times of it are recovered. Still, the larger part of an undersea cable lies offshore and is usually left on the site, so the actual energy recovery is small – just about few units per cent – compared with the energy (embodied + used for laying) required …

THE USE OF MBR SYSTEMS FOR THE TREATMENT OF REAL SHIPBOARD SLOPS: ANALYSIS OF BIOLOGICAL PERFORMANCE AND BIOMASS BIOKINETIC ACTIVITY

In order to prevent hydrocarbon discharge at sea from ships, the International Maritime Organization (IMO) enacted the MARPOL 73/78 convention in which any oil and oil residue discharged in wastewater streams must contain less than 5 ppm hydrocarbons. Effective treatment of this petroleum-contaminated water is essential prior to its release into the environment, in order to prevent pollution problem for marine ecosystems as well as for human health. The present paper reports the first results of a field gathering campaign aimed at gaining insight about the treatment of real shipboard slops with a MBR pilot plant, in terms of pilot performance and biomass biokinetic activity. The achieved re…

Experimental Sorting of Municipal-Like Waste in the Hospital “Civico”, Palermo (IT)

An experiment of source sorting - based management of Health Care Waste (HCW) was carried out in 2011 in 4 Departments of the Public Hospital “Civico” (Palermo, IT), where the basic mandatory separation between hazardous and non-hazardous waste was already going on since year 2000.The experiment consisted in weighing every day for 15 days 4 predefined fractions collected in the Infirmaries (namely paper, plastics, glass and unsorted fraction), and the bags with unsorted waste from the patient’s stay room. Furthermore, in 1 of the 4 Departments also the boxes of Infectious Waste (IW) were weighed for a week.As a result a weighted average value of 0.56 kg of Municipal-like Waste (MLW) per bed…

River water quality assessment: a hydrodynamic water quality model for propagation of pollutants

A hydrodynamic river water quality model is presented. The model consists of a quantity and a quality sub-model. The quantity sub-model is based on the Saint Venant equations. The solution of the Saint Venant equations is obtained by means of an explicit scheme based on space-time conservation. The method considers the unification of space and time and the enforcement of flux conservation in both space and time. On the other hand the quality sub-model is based on the advection dispersion equation. Particularly, the principle of upstream weighting applied to finite difference methods is employed. Such a method enables us to reduce the numerical dispersion, avoiding oscillation phenomenon. Th…

In sewer processes: mathematical model development and sensitivity analysis.

Until now the majority of sewer networks in Italy have been built and managed considering small as well as local wastewater treatment plants (WWTPs). However, pushed by Italian and EU regulations, centralised and large WWTPs are becoming more common in Italy. One major technical aspect caused by the changing from local to centralised WWTPs is the development of significant in-sewer processes. These processes are also emphasized by the building of long interceptor sewers characterized by high hydraulic retention times and absence of tributary sewers. In this paper a model derived from the well known WATS model (Wastewater Aerobic/anaerobic Transformation in Sewers) has been set up and applie…

Influence of operative conditions in a hybrid activated sludge/biofilm process for the treatment of municipal wastewater in a cold climate region: a case study

In the last years the idea to combine suspended and attached bomass by introducing suspended carriers into the aeration tank for biofilm attachment and growth was proposed. The increase of the overall sludge age in the system leads to a favourable environment for the growth of nitrifying bacteria, so that nitrification may be maintained throughout the winter. The main aim of the study was to investigate a hybrid MBBR process, mostly in terms of nitrification, when operating with different values of the sludge retention time (SRT), and highlighting the influence of temperature on the process. Based on experience in practice it was hypothesized that nitrification could be maintained at far lo…

erformances of a granular sequencing batch reactor (GSBR)

Wastewater modification processes in a stabilization reservoir: a new mathematical model

The paper presents a mathematical model for the simulation of the ecology of a wastewater stabilization reservoir (WSR). WSRs are hypertrophic aquatic systems devoted to water storage in warm countries where shortage conditions are often encountered. Several factors that affect the stabilization reservoir’s effluent quality were taken into account: hydraulics and hydrology, solar radiation, reaeration, algae, zooplankton, organic matter, pathogens, and sediment-water interactions. The model quantifies the specific influence of each factor on effluent quality, and evaluating the correlation between the different factors. State variables included in the model were: algae, dissolved oxygen, or…

Attività di monitoraggio di corpi idrici fluviali per l’individuazione dello stato di qualità: applicazione al bacino del fiume Oreto

Total emissions assessment from sewer and WWTP: a long term modelling approach

Relazione al 1° Seminario sui Processi a Membrana fra Département STE del Polytech' Montpellier (F) e Dipartimento Ingegneria Idraulica e Ambientale dell'Università di Palermo (I): EXPÉRIMENTATION SUR LA CROISSANCE DE LA BIOMASSE DANS UNE INSTALLATION PILOTE À MEMBRANES

Treatment of Oily Wastewater with Membrane Bioreactor Systems

The aim of the present work was to investigate the behavior of a membrane bioreactor (MBR) system for the treatment of oily wastewater. A bench scale MBR was fed with synthetic wastewater containing diesel fuel. Organic carbon, hydrocarbon and ammonium removal, kinetic constants, extracellular polymeric substances production, and membrane fouling rates were monitored. The MBR plant was operated for more than 200 days, and the results highlighted good carbon removal and nitrification, suggesting a sort of biomass adaptation to hydrocarbons. Membrane fouling analysis showed an increase in total resistance, likely due to hydrocarbons, which caused an irreversible fouling (pore blocking) mainly…

Wastewater Reuse Effects on Soil Hydraulic Conductivity

The wastewater total suspended solids (TSS) concentration effects on the saturated hydraulic conductivity, \iK\ds, of a clay and a loam soil were investigated on laboratory repacked soil cores by a constant head permeameter. Both municipal wastewater (MW) and artificial wastewater (AW) with different TSS concentrations were used, with the aim to evaluate, by comparison, the effects of biological activity. The development of a surface sealed layer was investigated in loam soil columns supplied with AW and equipped with water manometers at different depths to detect the hydraulic head gradient changes. In the loam soil, \iK\ds reduced to about 80% of the initial value after infiltration of 17…

Uncertainty in Quali-Quantitative Response of a Natural Catchment on a Daily Basis

Submarine outfalls in Sicily: a survey

Comparison between a detailed and a simplified integrated model for the assessment of urban drainage environmental impact on an ephemeral river

The benefit of integrated analysis has been demonstrated in technical literature and it is also required by the EU Water Framework Directive 60/2000, which proposes a water-quality-orientated view of the whole urban drainage system and oversees new ways of assessing its performance. Integrated models, such as any complex modelling approach, often have prohibitive data availability requirements that reduce their applicability. Moreover, widely different approaches can be applied, ranging from simple conceptual models to complex physically based ones. In the present paper, two approaches have been compared using data from an experimental catchment in Bologna ( Italy), which consists of a part…

MODELLAZIONE DELLA QUALITÀ DELLE ACQUE NEI RICETTORI IN TEMPO DI PIOGGIA

Controllo dell’inquinamento delle acque meteoriche e qualità dei corpi idrici ricettori: l’esperienza del bacino Nord di Palermo

Reattori a letto mobile ibridi per il trattamento di acque reflue urbane

Calibrazione dei parametri di qualità nelle reti di approvvigionamento idrico e caratterizzazione della diversità spaziale – applicazione ad un caso di studio

Influence of the Height of Municipal Solid Waste Landfill on the Formation of Perched Leachate Zones

Waste settlement as well as consolidation phenomena, which occur inside a landfill for municipal solid waste (MSW), can cause a decrease in waste permeability. This can lead to a reduction in conveyance of the leachate drainage system. It is therefore possible that a so-called perched leachate zone will form. Such a zone is constituted by an area in the body of the landfill where the leachate is temporarily trapped and is unable to infiltrate downward. This phenomenon is influenced by many factors, which include rain infiltration rate, waste moisture and composition, landfill height, and so on. The main aim of the paper is to elucidate the role played by landfill height in the formation of …

Stormwater infiltration trenches: a conceptual modelling approach.

In recent years, limitations linked to traditional urban drainage schemes have been pointed out and new approaches are developing introducing more natural methods for retaining and/or disposing of stormwater. These mitigation measures are generally called Best Management Practices or Sustainable Urban Drainage System and they include practices such as infiltration and storage tanks in order to reduce the peak flow and retain part of the polluting components. The introduction of such practices in urban drainage systems entails an upgrade of existing modelling frameworks in order to evaluate their efficiency in mitigating the impact of urban drainage systems on receiving water bodies. While s…

Trattamenti a membrana per il riutilizzo delle acque reflue nell’industria tessile

A new approach for assessing minimum flow in ephemeral streams

The aim of this paper is to propose a new methodological approach, appropriate for low-yielding catchments, by calculating the ecological minimum river flow starting from the river water quality based on biological indicators and physical–chemical characteristics as reported in the Italian Water Law no. 152/06 and in the UE 2000/60 Directive (WFD: Water Framework Directive). Actually, protecting and restoring river flow regimes and hence the ecosystems they support by providing environmental flows, has become a major aspect of river basin management. In detail, pollutant concentrations downstream and fluvial structure cross-sections have been evaluated, starting from discharges released dow…

The influence of rainfall time resolution for urban water quality modelling

The objective of this paper is the definition of a methodology to evaluate the impact of the temporal resolution of rainfall measurements in urban drainage modelling applications. More specifically the effect of the temporal resolution on urban water quality modelling is detected analysing the uncertainty of the response of rainfall–runoff modelling. Analyses have been carried out using historical rainfall–discharge data collected for the Fossolo catchment (Bologna, Italy). According to the methodology, the historical rainfall data are taken as a reference, and resampled data have been obtained through a rescaling procedure with variable temporal windows. The shape comparison between ‘true’…

Biogas from municipal solid waste landfills: A simplified mathematical model

AbstractMunicipal solid waste (MSW) landfills now represent one of the most important issues related to the waste management cycle. Knowledge of biogas production is a key aspect for the proper exploitation of this energy source, even in the post-closure period. In the present study, a simple mathematical model was proposed for the simulation of biogas production. The model is based on first-order biodegradation kinetics and also takes into account the temperature variation in time and depth as well as landfill settlement. The model was applied to an operating landfill located in Sicily, in Italy, and the first results obtained are promising. Indeed, the results showed a good fit between me…

Uncertainty assessment of an integrated urban drainage model

Over the last few years, the use of mathematical models has gained importance in urban drainage system management; indeed, such models enable the combined analysis of different components that constitute a drainage system; the sewer system, wastewater treatment plant and the receiving water body. The effectiveness of an integrated approach has been widely demonstrated in the past and is presented in the EU Water Framework Directive, which also introduces a new point of view regarding the water quality management of the whole system, requiring a global analysis at the river basin scale for pollutant sources. However, integrated urban drainage models introduce several uncertain factors that a…

IMPATTO DELLE ACQUE METEORICHE SUGLI IMPIANTI DI DEPURAZIONE

Sewer as a biological reactor: mathematical modelling as aid for sewer design issues

Assessment of data availability influence on integrated urban drainage modelling uncertainty

In urban water quality management, several models are connected and integrated for analysing the fate of pollutants from the sources in the urban catchment to the final recipient; classical problems connected with the selection and calibration of parameters are amplified by the complexity of the modelling approach increasing their uncertainty. The present paper aims at studying the influence of reductions in available data on the modelling response uncertainty with respect to the different integrated modelling outputs (both considering quantity and quality variables). At this scope, a parsimonious integrated home-made model has been used allowing for analysing the combinative effect of data…

Physical features of Health Care Waste

A monitoring work was recently carried out in two major Health Care Facilities (HCFs) in Italy, both located in Palermo, to obtain information on waste generation rates. Monitoring consisted in weighing infectious waste containers for 15 days in 4 Departments for each health care facility. From values obtained monthly production, specific weights and Production Indexes were calculated. The main producers of waste appeared Oncological DH and Resuscitation for both HCFs, with more than 4 and 3 kg measured per occupied place and day, respectively. About specific weight, apparent bulk values always below 200 kg/m3 were calculated. From the short observation performed it seems that notable impro…

Evaluation in microcosm of biostimulation and bioaugmentation efficacy on diesel-contaminated soil

Bioremediation is a promising technology for the treatment of hydrocarbon (HC) contaminated soils that is based on the biodegradation capacities of native or introduced microbial populations. Biotractability tests are essential for choosing the optimal bioremediation treatment. For this purpose, multiple microcosm tests, based on biostimulation by landfarming or bioventing and addition of nutrients, were conducted for 120 days on a soil contaminated by diesel, after assessing its intrinsic catabolic potential. An additional bioaugmentation treatment was performed for further 60 days by inoculating selected HC degrading bacteria. HC (C10-C40) concentration was monitored by GC-FID analysis an…

LA MODELLAZIONE DEI CORSI D’ACQUA A CARATTERE TORRENTIZIO: IL CASO DI STUDIO DEL FIUME ORETO

I modelli di qualità fluviale possono essere dei validi strumenti per la valutazione e la gestione della qualità dei corpi idrici ricettori. Tuttavia tali modelli richiedono una calibrazione accurata al fine di valutare i parametri che in essi compaiono; ciò richiede una vasta banca dati di qualità, raramente disponibile nel caso di piccoli corsi d’acqua fluviali a carattere torrentizio, per il limitato interesse spesso prestato a tali tipologie di corpi idrici. Nella memoria viene presentato un modello semplificato di qualità fluviale; il modello trae spunto dal classico modello di Streeter e Phelps, integrato al fine di tener conto dei principali processi fisici, chimici e biologici per l…

I reattori aerobici granulari: esperienze con refluo reale e sintetico

La granulazione aerobica può essere ottenuta nei sistemi con alimentazione discontinua in due differenti configurazioni impiantistiche, che permettono di realizzare i necessari sforzi tangenziali per la formazione dei granuli: il Sequencing Batch Bubble Column Reactor (SBBC) e il Sequencing Batch Airlift Reactor (SBAR). Lo scopo di questo studio è stato quello di osservare il fenomeno della granulazione aerobica e valutare il ruolo del tempo di sedimentazione durante la fase di selezione e formazione dei granuli. L’intera sperimentazione è stata suddivisa in due diverse campagne sperimentali in cui è stato utilizzato refluo sintetico, nella prima, e refluo reale, nella seconda. Al fine di e…

Monitoring activity to assess the quality conditions of a river: the case study of Oreto, Italy

Catchment scale modeling approach for a holistic urban water quality management

Diversita’ spaziale del cloro residuo nelle reti di approvvigionamento idrico

La qualità dell’acqua nelle reti di distribuzione può essere sensibilmente alterata da una serie di processi che si sviluppano sia lungo il sistema di adduzione che nella stessa rete di distribuzione. La riduzione della concentrazione di cloro, utilizzato per la disinfezione delle acque, può essere considerata un indice del progressivo deterioramento delle caratteristiche igieniche dell'acqua circolante in rete. La concentrazione del cloro, libero o combinato, è infatti strettamente legata alle reazioni che si sviluppano all’interno delle condotte. In questo lavoro particolare attenzione è rivolta alla identificazione della diversità spaziale del cloro residuo in rete. L’analisi viene condo…

MODELLING BIOGAS GENERATION AND RELEASE FROM MUNICIPAL SOLID WASTE LANDFILLS

MSW sanitary landfills represent nowadays one of the most important issue related to the waste management cycle. In particular, knowledge about biogas production is a key aspect for a proper exploitation of this energy source, even in the after-care phase. In the present study, a simple mathematical model was proposed for the simulation of biogas production. The model is based on 1st order biodegradation kinetic and takes also into account the temperature variation in time and depth and the landfill settlement. The model was applied to a real landfill located in Sicily (ITALY) and its simulation result was compared with experimental data (volumes of biogas collected by the recovery system a…

Uncertainty assessment of sewer sediment erosion modelling

Urban stormwater quality modelling has become a fundamental issue in the evaluation of the receiving water bodies' quality state. Laboratory study as well as field campaigns have widely demonstrated that combined sewer sediments present cohesive-like properties which increase their resistance to erosion. However, only few models take sewer sediments into account considering their rheological properties. In the present paper different sewer sediment erosion models have been tested and their uncertainties have been assessed. The main goal was to discriminate the algorithms with respect to their robustness and the reduction of uncertainty. In order to accomplish such objective the GLUE methodo…

Controllo dell'inquinamento delle acque meteoriche e qualità dei corpi idrici ricettori

IL MONITORAGGIO DELLE EMISSIONI E DELLA QUALITÀ DELL’ARIA NELLA GESTIONE DELLE DISCARICHE

La corretta gestione delle discariche controllate, destinate allo smaltimento dei rifiuti urbani, in fase operativa e post‐operativa, richiede il controllo dei potenziali impatti che esse possono determinare nei vari comparti ambientali interessati. Fra questi, la produzione di biogas derivante dai processi metabolici di trasformazione della frazione organica dei rifiuti, richiede, da un lato, la realizzazione di efficaci sistemi di estrazione, mediante i quali è pure possibile produrre energia termica e/o elettrica, dall’altro, il controllo delle emissioni diffuse in atmosfera, che contribuiscono al peggioramento delle caratteristiche dell’aria ambiente circostante il sito della discarica,…

ASSESSMENT OF BEACH LITTER ALONG THE COAST: CASE STUDY OF THE CITY OF CADIZ (SPAIN)

The United Nations Environment Program defines as waste all the persistent marine debris deposited or abandoned in the sea (marine litter) and beach (beach litter) environment. Thus including all substances or products abandoned or involuntarily dispersed into the sea or on the coastline. It has been estimated that, all around the world, about 10 million tons of waste coming from domestic, commercial and industrial activities reach the seas every year. Moreover, waste floating adrift in the seas and oceans can be carried very far away, reaching different places from the ones they were originated. Further, damage may result to various human activities and equipment, such as navigation, energ…

Il destino dei microinquinanti negli impianti di depurazione

La problematica dell’inquinamento prodotta dai microinquinanti, cioè da sostanze presenti in tracce nei corpi ricettori, ma aventi caratteristiche tali da comportare possibili danni per l’ambiente e per l’uomo, ha assunto un’importanza sempre crescente nell’ultimo ventennio. Infatti essa è ormai oggetto di diversi interventi normativi a livello comunitario e nazionale, che hanno individuato un elenco di sostanze definire “prioritarie” e “pericolose prioritarie”, di cui sono state fissate le concentrazioni massime per i corpi ricettori al fine di garantire voluti livelli di qualità ambientale; a queste si aggiunge un elenco molto numeroso di “contaminanti emergenti”, non ancora oggetto di no…

Cultivation of granular sludge with hypersaline oily wastewater

The time required to stabilise mature aerobic granules is rather variable. In addition, cultivation time and the structural characteristics of granules seem to be related to the nature of wastewater influent. Granular sludge has been used for the treatment of several industrial wastewaters, but nothing has been reported about wastewater characterized by the simultaneous presence of hydrocarbons and high chloride concentration. In this work, the authors analysed the granulation process and performance as well as the physical characteristics of aerobic granules in two Granular Sequencing Batch Airlift Reactors (GSBARs), fed with acetate-based synthetic wastewater in reactor 1 (R1) and with a …

The Influence of MSW Landfill Height in the Perched Leachate Formation

During the last decades, the largest part of municipal solid waste (MSW) generated world wide has been disposed of in landfills without any pre-treatment. The main environmental impacts of such landfills, containing high amounts of biodegradable organic matter, are caused by emissions of liq-uid effluents and landfill gas. With no collection and treatment, leachates from landfills pollute groundwater and soils locally. Furthermore, besides the biological processes, many physical phe-nomena occur inside the landfill body which negatively affect landfill management. Indeed, the waste settlement inside the landfill body, with a consequent increase of its density, corresponds to a proportional …

Simultaneous sludge minimization, biological phosphorous removal and membrane fouling mitigation in a novel plant layout for MBR.

Abstract The integration of one anaerobic reactor in the mainstream (AMSR) of a pre-denitritication-MBR was evaluated with the aim to achieve simultaneous sludge minimization and phosphorous removal. The excess sludge production was reduced by 64% when the AMSR was operated under 8 h of hydraulic retention time (HRT). The highest nutrients removal performances referred to organic carbon (98%), nitrogen (90%) and phosphorous (97%) were obtained under 8 h of HRT. In contrast, prolonged anaerobic-endogenous conditions were found to be detrimental for all nutrients removal performances. Similarly, the lowest membrane fouling tendency (FR = 0.65∙1011 m−1 d−1) was achieved under 8 h of HRT, where…

Modellazione matematica degli interventi di messa in sicurezza di un sito contaminato

Data availability impact on integrated modelling reliability throughout identifiability analysis

Modelling of hybrid moving bed biofilm reactors: a pilot plant experiment.

In recent years there has been an increasing interest in the development of hybrid biofilm reactors, especially in the upgrading of existing WWTP that are no longer able to respect concentration limits. In fact, today's challenge is the achievement of a good aquatic state for the receiving water bodies according to the Water Framework Directive requirements, which indeed limit even more the continuous emissions, i.e. coming from WWTP. This paper presents the setting up of a mathematical model for the simulation of a hybrid MBBR system; the model calibration/validation has been carried out considering a field gathering campaign on an experimental pilot plant. The main goal is to gain insight…

Global sensitivity analysis in ASM applications: comparison of the SRC and Extended-FAST method for a UCT-MBR model

In this study global sensitivity analysis is performed to identify influential as well as non-influential parameters in a model of a University Cape Town Membrane Bioreactor (UCT-MBR). In particular, the Standardised Regression Coefficients (SRC) and Extended-FAST sensitivity analysis methods are applied. The sensitivity of model variables towards parameter variation is analysed for CODTOT, SNH4, SNO3, SPO, and MLSS along five reactor compartments. Both methods indicate that the parameters identified as being influential differ from section to section due to the different processes involved. Moreover, the relevant influence of the membrane filtration parameters is detected in the first plan…

Mathematical modelling of biogas from municipal solid waste landfil

Sanitary landfills for municipal solid wastes can be considered as large biological reactors where the organic fraction of municipal solid waste undergoes anaerobic digestion producing gas and liquid emissions. Leachate production from municipal sanitary landfills is currently recognized as a major environmental burden associated with municipal solid waste management and it may be responsible for local pollution of groundwater and soil. Moreover, the fate of the organic compounds within the landfill body is of primary importance since it directly influences the production of landfill gas. The aim of the paper is to propose an integrated mathematical model able to simulate, on one hand, the …

Nutrient sources in a Mediterranean catchment and their improvement for water quality management

Changes in land-use or management strategies may affect water outflow, sediment and nutrients loads. Thus, there is an increasing demand for quantitative information at the catchment scale that would help decision makers or planners to take appropriate decisions. The characterisation of water status, the description of pollution sources impact, the establishment of monitoring programs and the implementation of river basin management plans require an analysis of the current basin status and estimates of the relative significance of the different sources of pollution. Particularly, in this study the Soil and Water Assessment Tool (SWAT2000) model was considered since it is an integrated hydro…

Direct Measurement of Methane Emission Rates: Multiyear Application to a Municipal Landfill in Southern Italy

Municipal Solid Waste (MSW) landfills have been identified as one of the most important sources of methane (CH4) emission. MSW contains a certain amount of biodegradable organic matter which undergoes anaerobic degradation resulting in the production of the landfill gas (LFG), which main component is tipically represented by CH4. In order to minimise its negative effects on the envi-ronment, LFG recovery is a suitable tool to control CH4 emissions from a landfill site and the measurement of CH4 emissions represents a good way to evaluate the effectiveness of LFG recover-ing system in reducing biogas emission to the atmosphere. However, up to now few measurements of landfill CH4 emissions ha…

Influenza dei polimeri extracellulari sul fouling e sul foaming negli impianti MBR.

L’applicazione sempre più diffusa dei bioreattori a membrana presenta tuttavia ancora alcuni fattori limitanti che ne condizionano l’adozione: infatti sono ancora incerte le previsioni della vita utile e dell’efficienza della barriera filtrante. In particolare, notevole incidenza sul processo ha il fouling, causato principalmente dai fenomeni di sporcamento condizionati prevalentemente dalla composizione della sospensione biologica sottoposta a filtrazione. Nella nota sono riportati i risultati di uno studio sperimentale che ha avuto per oggetto l’analisi dell’influenza di alcuni parametri specifici che, oltre a descrivere la qualità del fango attivo dei sistemi MBR, influenzano il processo…

A model for biological nitrogen and phosphorus removal: application to a full scale WWTP Proc. - Firenze 24-27/06/2008

Comparison of a MBR system start-up with and without inoculum: experimental and mathematical model application

The performance of a membrane bioreactor (MBR) system and the extension and mechanisms that lead to the formation of the fouling may differ in relation to the start-up. As a consequence, the MBR start-up may constitute a crucial point that drastically influence the MBR performance in its lifespan. Indeed, the start-up influences the mechanisms of membrane fouling whose effects, in the case of irreversible cake deposition, can be modified only by a chemical membrane washing. In order to gain insights about the effect of the start-up on a MBR system, a MBR pilot plant was build-up and a mathematical model developed. The MBR system was constituted by a hollow fibre membrane module installed in…

The role of extracellular polymeric substances (EPS) on aerobic granules formation: comparison between a case of synthetic wastewater supply and another of industrial wastewater

The paper focused on the evolution and the comparison of the extracellular polymeric substances (EPSs) content during the granulation process in two Granular Sequencing Batch Airlift Reactors (GSBAR) (3,5 L) fed with synthetic (R1) and industrial wastewater (R2). The results showed that in both the reactors the EPSs, in particular proteins (PN), were mainly produced during the feast phase because of the high substrate availability, especially under conditions of metabolic stress. Then, the EPSs content reduced during the famine period, because of biodegradation by bacteria. More in detail, during the granulation process, a greater polysaccharides (PS) consumption occurred in both reactors, …

Uncertainty in urban stormwater quality modelling: The effect of acceptability threshold in the GLUE methodology

Uncertainty analysis in integrated urban drainage modelling is of growing importance in the field of water quality. However, only few studies deal with uncertainty quantification in urban drainage modelling; furthermore, the few existing studies mainly focus on quantitative sewer flow modelling rather than uncertainty in water quality aspects. In this context, the generalised likelihood uncertainty estimation (GLUE) methodology was applied for the evaluation of the uncertainty of an integrated urban drainage model and some of its subjective hypotheses have been explored. More specifically, the influence of the subjective choice of the acceptability threshold has been detected in order to ga…

An integrated model for biological and physical process simulation in membrane bioreactors (MBR).

Abstract Mathematical modelling of membrane bioreactors (MBRs) for wastewater treatment has targeted either the biological processes (treatment quality target) as well as various aspects of system management. However, the high number of interactions among the involved physical–chemical processes, hampers a straightforward mathematical modelling. This circumstance is much more emphasized for submerged MBR systems where the membrane is immersed in an aeration tank. One of the main crucial points that prevents a comprehensive understanding is the interpretation of the fouling phenomenon and its connections with the biological processes. An overall mathematical model for MBR has not been comple…

Start-up with or without inoculum? Analysis of an SMBR pilot plant.

This study analysed a submerged membrane bioreactor (SMBR) start-up with the purpose of determining the best conditions to carry it out. In order to do this, a hollow fibre membrane module was installed in a submerged configuration in a pilot aerobic reactor. The experiment was then divided in two phases, lasting 65 days each. During phase 1, the pilot plant was started-up without inoculum of activated sludge and no sludge, withdrawal was performed. Conversely, in phase 2, the MBR pilot plant was started-up with sludge inoculum and the sludge concentration was kept constant. In both phases, the volumetric loading rate applied to the pilot plant was kept constant. The authors analysed the di…

Indagine sulla produzione dei rifiuti sanitari nella Provincia di Palermo

Performances of a granular sequencing batch reactor (GSBR).

Aerobic granulation in sequencing batch reactors is widely reported in literature and in particular in SBAR (Sequencing batch airlift reactor) configuration, due to the high localised hydrodynamic shear forces that occur in this type of configuration. The aim of this work was to observe the phenomenon of the aerobic granulation and to confirm the excellent removal efficiencies that can be achieved with this technology. In order to do that, a laboratory-scale plant, inoculated with activated sludge collected from a conventional WWTP, was operated for 64 days: 42 days as a SBAR and 22 days as a SBBC (sequencing batch bubble column). The performances of the pilot plant showed excellent organic…

Uncertainty assessment of a model for biological nitrogen and phosphorus removal: Application to a large wastewater treatment plant

Abstract In the last few years, the use of mathematical models in WasteWater Treatment Plant (WWTP) processes has become a common way to predict WWTP behaviour. However, mathematical models generally demand advanced input for their implementation that must be evaluated by an extensive data-gathering campaign, which cannot always be carried out. This fact, together with the intrinsic complexity of the model structure, leads to model results that may be very uncertain. Quantification of the uncertainty is imperative. However, despite the importance of uncertainty quantification, only few studies have been carried out in the wastewater treatment field, and those studies only included a few of …

Hybrid moving bed biofilm reactors: an effective solution for upgrading a large wastewater treatment plant

Over the last few years there has been a growing attention regarding the receiving water body quality state. As a matter of a fact, the Directive 91/271 of the European Union (EU) replaced the “emission standard” concept that fixes discharge limits depending on polluting emission characteristics, with the “stream standard” concept that fixes discharge limits for each polluting substance depending on self-depurative characteristics of the RWB. In this context, several WWTPs need to be upgraded in order to meet stricter effluent limits. The need of WWTP upgrading was also emphasized by the growing urbanization that have led, in most cases, to get overloaded WWTP due to an overcoming of the ma…

PERFORMANCE OF A MBR PILOT PLANT SUBJECT TO A GRADUAL SALINITY INCREASE: ANALYSIS OF BIOKINETIC AND FOULING BEHAVIOR

Membrane bioreactors (MBRs) have been widely used for the treatment of various wastewater, including municipal, industrial, landfill leachate (Wintgens et al., 2005). Such systems generally provide decisive advantages compared to conventional activated sludge (CAS) processes: in particular, they feature high quality effluent, small footprint and low sludge production rates (Stephenson et al., 2000). In recent years MBRs have also been used for the treatment of specific saline water, such as wastewater produced from shipboard activities, aquaculture wastewater or wastewater deriving by sediment washing treatment, as an example. However, when subject to salinity, a modification of biomass cha…

Characterization of wastewater and biomass activity in a membrane bioreactor using respirometric techniques

Over the last two decades, Membrane Bioreactors (MBRs) emerged even more for wastewater treatment, ensuring high removal efficiencies as well as very small footprint required. Indeed, in this kind of process, a modification in biomass activity and viability can exist compared to that of a conventional activated sludge (CAS) process. In this context, respirometric analysis represents a reliable tool in order to evaluate the actual biomass kinetic parameters, to insert in mathematical models in the design phase, as well as to monitor the biomass viability, especially when these processes are operated with high sludge retention time (SRT) values. The paper presents some results of respirometri…

Un nuovo approccio per la determinazione del deflusso minimo vitale nei corsi d’acqua a carattere torrentizio.

Role of Modeling Uncertainty in the Estimation of Climate and Socioeconomic Impact on River Water Quality

AbstractClimate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty and the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based…

The role of EPS concentration in MBR foaming: analysis of a submerged pilot plant.

Foaming in Membrane BioReactor (MBR) is a frequently discussed topic. Some authors reported that the phenomenon is due to filamentous organisms, like at Conventional Activated Sludge (CAS) plants. However, in recent years, other authors reported that the Extra-cellular Polymer Substances (EPSs) concentration is an important factor for controlling foam as well. Nevertheless, even if a number of MBR plants are affected by foaming, presently there are no suitable methods to evaluate the phenomenon. To facilitate the study of this controversial phenomenon in an MBR system, certain foam tests proposed in the past for CASPs were investigated. The results of the tests were able to adequately measu…

Physical properties and Extracellular Polymeric Substances pattern of aerobic granular sludge treating hypersaline wastewater.

The modification of the physical properties of aerobic granular sludge treating fish-canning wastewater is discussed in this paper. The structure and composition of the Extracellular Polymeric Substances (EPSs) were analyzed at different salinity levels and related to granules stability. Results outlined that the total EPSs content increased with salinity, despite the EPSs increment was not proportional to the salt concentration. Moreover, the EPSs structure was significantly modified by salinity, leading to a gradual increase of the not-bound EPSs fraction, which was close to the 50% of the total EPSs content at 75 g NaCl L-1. The increasing salt concentration modified also the EPSs compos…

Emission standards versus immission standards for assessing the impact of urban drainage on ephemeral receiving water bodies

In the past, emission standard indicators have been adopted by environmental regulation authorities in order to preserve the quality of a receiving water body. Such indicators are based on the frequency or magnitude of a polluted discharge that may be continuous or intermittent. In order to properly maintain the quality of receiving waters, the Water Framework Directive, following the basic ideas of British Urban Pollution Manual, has been established. The Directive has overtaken the emission-standard concept, substituting it with the stream-standard concept that fixes discharge limits for each polluting substance depending on the self-depurative characteristics of receiving waters. Stream-…

“Modellazione dell’impatto dei deflussi urbani sui corpi idrici ricettori attraverso un approccio integrato”. La tutela idraulica ed ambientale dei territori urbanizzati. Atti dei seminari. Parma (5-6 febbraio 2004) e Cosenza (13-15 dicembre 2004)

Global sensitivity analysis for micropollutant modeling by means of an urban integrated approach

The paper presents the sensitivity analysis of an integrated urban water quality system by means of the global sensitivity analysis (GSA). Specifically, an home-made integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole - SMX). The model is able to estimate also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and the receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Five scenarios each characterized by different combinations of sub-systems (i.e., SS, WWTP an…

REMOTE SENSING ANALYSIS COUPLED TO FIELD MEASUREMENTS FOR THE EVALUATION OF METHANE EMISSIONS FROM A LANDFILL SITE: A CASE STUDY

SUMMARY: the waste disposal in sanitary landfills generates landfill gas (LFG), mainly constituted by methane (CH4) and carbon dioxide (CO2), because of the anaerobic degradation of the organic matter contained in the disposed waste. It is worth mentioning that CH4 is recognized as one of the most important contributor to global warming and sanitary landfills for Municipal Solid Waste (MSW) have been found to be a significant source of CH4 generation and emission. The main aim of the present work was the evaluation of methane emissions from a Sicilian landfill site by coupling of direct field measurements and ground temperature data acquired through remote sensing techniques. It is worth me…

EVALUATION OF DIFFUSE AND CONCENTRATED POLLUTION AT WATERSHED SCALE

The study presents an integrated approach in order to analyse and quantify pollution dynamics at basin scale depending on concentrated and diffuse sources. More specifically, an integrated model for urban drainage system has been exploited in order to simulate the complex sewer network - wastewater treatment plant and receiving water body. Moreover, a quali-quantitative model has been developped in order to simulate the non-point sources pollutant (agricultural and zoo-technical) in term of water river discharges and nutrient, produced from the wash off of soils. Finally, different models have been coupled in order to reconstruct the whole pollutant load for the receiving water body and to …

Analisi modellistica dello stato di contaminazione delle acque di falda e degli interventi di messa in sicurezza d’emergenza

Influence of the Oxic-Settling-Anaerobic (OSA) Process on Methane Production by Anaerobic Digestion of Sewage Sludge

The present study evaluated different sludge-reduction mechanisms in the oxic-settling-anaerobic (OSA) process in terms of their effects on methane productivity by anaerobic digestion of sewage sludge. Two different layouts were investigated for the sludge return from an anaerobic side-stream reactor (ASSR) to the anoxic (scheme A) or the aerobic (scheme B) reactor of a pre-denitrification plant. Biochemical methane-potential (BMP) assays performed on the excess sludge revealed that scheme A promoted an overall increase of methane production in the OSA (20 mLCH4 gVSS−1d−1, +19%), although compared with a control CAS plant a significant decrease in the excess sludge production (3…

Assessment of data and parameter uncertainties in integrated water-quality model

In integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating sewer system, wastewater treatment plant and receiving water body), uncertainty produced in one sub-model propagates to the following ones depending on the model structure, the estimation of parameters and the availability and uncertainty of measurements in the different parts of the system. Uncertainty basically propagates throughout a chain of models in which simulation output from upstream models is transferred to the downstream ones as input. The overall uncertainty can differ from the simple sum of uncertainties generated in each sub-model, dep…

Interpreting and modelling field data for wastewater dispersion into sea trough dimensional analysis

This paper deals with the mathematical and experimental characterization of a coastal urban wastewater discharge in the South Tyrrhenian Sea, namely the Golfo di Palermo, western Sicily (Italy). The stretch of water lying before the central part of the capital town receives the wastewater originating from about 200 000 inhabitants. The sewage is currently still discharged on-shore without any prior treatment by a free-surface outfall called “Porta Felice”. The Municipality is currently implementing a plan to connect the sewerage system of these areas to the main wastewater treatment plant; at the moment, however, no mitigation measure has been applied yet and the quality of the Gulf is stil…

A comprehensive comparison between halophilic granular and flocculent sludge in withstanding short and long-term salinity fluctuations

The effects of salinity fluctuations on the activity of autochthonous halophilic bacteria in aerobic granular sludge (AGS) and flocculent activated sludge (FAS) reactors were investigated. The response of nitrifiers and denitrifiers activity to drastic and moderate salinity shocks in the short-term (ST) and long-term (LT) was examined. The BOD5removal efficiency decreased only in the reactors subjected to the drastic LT salinity increase. Nevertheless, stable performances were achieved 18 days after the shock in the AGS-R1 (90%), whereas after 27 days in the FAS-R1 (82%). The loss in nitritation efficiency was higher in the FAS reactors and was proportional to the shock intensity. Nitritati…

Membrane bioreactors sludge: From production to disposal

Abstract This chapter reviews the MBR activated sludge from production to disposal. Starting from sludge characterization, the chapter first presents the features of MBR sludge (morphology and EPS chemical composition), also in terms of differences with the activated sludge from conventional activated sludge plants. Sludge dewaterability is then discussed, focusing on the differences between aerobically and anaerobically digested sludge. An analysis of the costs related to MBR sludge treatment and disposal also is presented in order to provide a framework for a sustainable MBR sludge management.

Enhanced Sewage Sludge Drying with a Modified Solar Greenhouse

This work reports the results obtained with an innovative configuration of a closed-static solar greenhouse for sludge drying. The novelty of the solar greenhouse configuration consisted in using a forced ventilation system to provide hot air for sludge drying and the utilization of solar irradiation for energy supply. Wet sewage sludge (97% humidity) was successfully dried up to a residual humidity close to 5% after 25 days during wintertime. The increase of the airflow rate supplied under the sludge bed improved the sludge drying rate. Moreover, the fraction of volatile suspended solids decreased from 70% to 41% after 13 days, indicating that air supply promoted the simultaneous stabiliza…

Capitolo 12 - Interventi per il trattamento delle acque di pioggia

Integration between quality models and GIS to assess water bodies quality conditions. An application to the Platani river

Formation Of perched leachate zones in MSW landfill

The paper presents a 1D mathematical model for the simulation of the percolation fluxes throughout a landfill for municipal solid waste (MSW). Specifically, the model is based on mass balance equations, that enable one to simulate the formation of perched leachate zones in a landfill for MSW. The model considers the landfill divided in several layers evaluating the in and out flow throughout each layer as well as the continuous moisture distribution. The infiltration flow is evaluated by means of the Darcy’s law for an unsaturated porous medium, while the moisture distribution evaluation has been carried out on the basis of the theory of the vertically distributed unsaturated flow. The solu…

CONTROLLO DELL’INQUINAMENTO DELLE ACQUE METEORICHE E QUALITÀ DEI CORPI IDRICI RICETTORI: L’ESPERIENZA DEL BACINO NORD DI PALERMO

Simultaneous nitritation-denitritation for the treatment of high-strength nitrogen in hypersaline wastewater by aerobic granular sludge

Abstract Fish processing industries produce wastewater containing high amounts of salt, organic matter and nitrogen. Biological treatment of such wastewaters could be problematic due to inhibitory effects exerted by high salinity levels. In detail, high salt concentrations lead to the accumulation of nitrite due to the inhibition of nitrite-oxidizing bacteria. The feasibility of performing simultaneous nitritation and denitritation in the treatment of fish canning wastewater by aerobic granular sludge was evaluated, and simultaneous nitritation–denitritation was successfully sustained at salinities up to 50 gNaCl L −1 , with a yield of over 90%. The total nitrogen concentration in the efflu…

The role of extracellular polymeric substances (EPS) on aerobic granules formation: comparison between a case of synthetic wastewater supply and another of industrial wastewater

The paper focused on the evolution of extracellular polymeric substances (EPSs) content during the granulation process in two Granular Sequencing Batch Airlift Reactors (GSBAR) (3,5 L) fed with synthetic and industrial wastewater. Results showed that EPSs, in particular proteins (PN) were mainly produced during the feast phase because of high substrate availability, especially under conditions of metabolic stress. Than EPSs content reduced during the famine period. More in detail, during the granulation process, a greater polysaccharides (PS) consumption occurred in both reactors, while PN content reduced significantly only in R2. As a result PN/PS ratio increased significantly during granu…

Analisi della fase di start-up di un bioreattore a membrana

L’applicazione dei sistemi MBR, pur garantendo elevati rendimenti di rimozione, è ancora oggi limitata, a causa di alcuni fattori che ne condizionano il funzionamento. Tra questi, uno dei principali è il fouling dovuto ai fenomeni di sporcamento della membrana da parte della sospensione biologica. Nella memoria si riportano i primi risultati di uno studio che ha avuto l’obiettivo di definire l’evoluzione e l’influenza del fouling sul processo di filtrazione durante la fase di avviamento dell’impianto, avvenuto senza inoculo iniziale di fango. La sperimentazione è stata condotta in un impianto pilota costituito da un bioreattore all’interno del quale è stato installato il modulo di membrane …

Urban drainage impact assessment on receiving water body: long-term simulation and statistical analysis

Comparison between moving bed-membrane bioreactor (MB-MBR) and membrane bioreactor (MBR) systems: Influence of wastewater salinity variation

Two pilot plant systems were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were analyzed. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the por…

The sludge dewaterability in advanced wastewater treatment: a survey of four different Membrane BioReactor pilot plants

The wasted activated sludge dewaterability represents a major concern for Wastewater Treatment Plants (WWTPs) managers. Indeed, whereas the dewatered sludge could represents a re-usable matrix, the principal drawback related to the wasted sludge dewaterability is the high water content due to the presence of extracellular polymeric substances (EPS) that allow the trapping of water molecules within the bio sludge flocs. In order to provide an outlook of the dewaterability features of activated sludge derived from advanced WWTP, the present research reports a long term survey (over two years) aimed at assessing the principal dewaterability parameters of the sludge wasted from different Membra…

THE INFLUENCE OF LANDFILL FEATURES AND SIDE SLOPES ON METHANE EMISSION RATES

Sanitary landfills for Municipal Solid Waste (MSW) disposal have been identified as one of the most important sources of methane (CH4) emissions; indeed, MSW contains a certain amount of biodegradable organic matter which undergoes anaerobic degradation resulting in the production of the so called landfill gas (LFG), which main component is typically represented by CH4. In general, LFG will escape through any faults in the landfill capping or in the LFG collection system. If the capping is not damaged, low quantities of LFG will be emitted through the permeable material that covers the disposed waste. On the other hand, some zones of the capping are often more permeable than others (e.g. si…

Physical dispersion and disappearance of bacteria in the Golfo di Palermo: the results of two surveys.

This paper reports on some results of two surveys at sea carried out in the surroundings of a urban wastewater discharge on the coast of the Golfo di Palermo, western Sicily (Italy). At the time of the surveys (year 2005) the stretch of water lying before the central part of the capital town received the untreated wastewater originating from about 200 000 inhabitants, which was discharged on-shore without any prior treatment by the free-surface outfall of “Porta Felice main sewer”. This outfall has crucial importance in the water quality; indeed, the Municipality is steadily implementing a plan featuring an intercepting main sewer along the coast and some pumping stations to connect all the…

Performance of membrane bioreactor (MBR) systems for the treatment of shipboard slops: Assessment of hydrocarbon biodegradation and biomass activity under salinity variation

In order to prevent hydrocarbon discharge at sea from ships, the International Maritime Organization (IMO) enacted the MARPOL 73/78 convention in which any oil and oil residue discharged in wastewater streams must contain less than 5. ppm hydrocarbons. Effective treatment of this petroleum-contaminated water is essential prior to its release into the environment, in order to prevent pollution problem for marine ecosystems as well as for human health. Therefore, two bench scale membrane bioreactors (MBRs) were investigated for hydrocarbon biodegradation. The two plants were initially fed with synthetic wastewater characterised by an increasing salinity, in order to enhance biomass acclimatio…

Insights on mechanisms of excess sludge minimization in an oxic-settling-anaerobic process under different operating conditions and plant configurations

In the present research, insights about the mechanisms of excess sludge minimization occurring in an oxic-settling-anaerobic (OSA) were provided. The investigation involved two systems operating in parallel. In particular, a conventional activated sludge (CAS) system as control and a system implementing the OSA process both having a pre-denitrification scheme were considered. Five periods (P1-P5) were studied, during which several operating conditions and configurations were tested. Specifically, the hydraulic retention time (HRT) in the anaerobic reactor of the OSA system (P1 8 h, P2-P3 12 h, P4 8 h, P5 12 h) and the return sludge from the anaerobic to the anoxic (scheme A) (P1-P2) or aero…

Evaluation of biomass activity and wastewater characterization in a UCT-MBR pilot plant by means of respirometric techniques

Abstract Over the last two decades, Membrane Bioreactors (MBRs) emerged even more for wastewater treatment, ensuring high removal efficiencies as well as very small footprint requirements. Indeed, in this kind of process, a modification in biomass activity and viability can exist compared to that of a CAS process. In this context, respirometric analysis represents a reliable tool in order to evaluate the actual biomass kinetic parameters, to insert in mathematical models in the design phase, as well as to monitor the biomass viability, especially when these processes are operated with high SRT values. The paper presents some results of respirometric techniques applied for the characterisati…

A model for wastewater organic removal and fouling development in a SMBR pilot plant.