Search results for "activated sludge"
showing 10 items of 143 documents
Application of the General Model "Biological Nutrient Removal Model No.1" to upgrade two full-scale WWTPs
2012
In this paper, two practical case studies for upgrading two wastewater treatment plants (WWTPs) using the general model BNRM1 (Biological Nutrient Removal Model No. 1) are presented. In the first case study, the Tarragona WWTP was upgraded by reducing the phosphorus load to the anaerobic digester in order to minimize the precipitation problems. Phosphorus load reduction was accomplished by mixing the primary sludge and the secondary sludge and by elutriating the mixed sludge. In the second case study, the Alcantarilla WWTP, the nutrient removal was enhanced by maintaining a relatively low dissolved oxygen concentration in Stage A to maintain the acidogenic bacteria activity. The VFA produce…
Nitrous oxide emission from a moving bed membrane biofilm reactor: the effect of the sludge retention time
2016
The aim of the present study was to investigate the nitrous oxide (N2O) emissions from a University of Cape Town (UCT) moving bed membrane bioreactor pilot plant. An experimental campaign was carried out during 60 days with three different sludge retention time (SRT). The pilot plant reactor was provided of funnel shape covers that guaranteed gas accumulation in the headspace. The results highlighted that N2O concentrations significantly increased when the biofilm concentrations increased within the aerobic and anoxic compartments. Furthermore, results have shown an increase of N2O with the decrease of SRT. Moreover, the MBR tank resulted the key emission source (up to 70% of the total N2O …
Aeration tank and secondary clarifier as one system. in "Activated Sludge Separation Problems: Theory, Control Measures, Practical Experieces. Eds. R…
2017
Traditionally the activated sludge process is treated as two stage process. The first stage (aeration basin) is described in terms of biological processes while the description of the second stage concentrates on processes of biomass separation and thickening. The modern approach to the activated sludge process looks at both the biological and the separation stage as one system. The aim of this chapter is to explain the interactions between the two parts of the activated sludge system.
Foaming estimation tests in activated sludge systems.
2005
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…
Obtención de los principales parámetros del agua residual urbana empleados en los modelos matemáticos de fangos activados a partir de una caracteriza…
2017
El tratamiento de las aguas residuales se ha realizado en España mediante procesos biológicos como el comúnmente utilizado de fangos activados. Estos procesos han sido descritos mediante modelos matemáticos que describen la eliminación de los contaminantes presentes en el agua (materia orgánica, nitrógeno y fósforo). La utilización de estos modelos requiere de una caracterización detallada de los contaminantes presentes en el agua residual urbana (ARU). La caracterización de un ARU es clave para el uso de estos modelos de simulación, tanto en el diseño como en la simulación de las Estaciones Depuradoras de Aguas Residuales (EDAR). Este trabajo ha utilizado y considerado los parámetros propu…
Effect of biomass features on oxygen transfer in conventional activated sludge and membrane bioreactor systems
2019
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…
Abatement of styrene waste gas emission by biofilter and biotrickling filter: comparison of packing materials and inoculation procedures.
2015
The removal of styrene was studied using 2 biofilters packed with peat and coconut fibre (BF1-P and BF2-C, respectively) and 1 biotrickling filter (BTF) packed with plastic rings. Two inoculation procedures were applied: an enriched culture with strain Pseudomonas putida CECT 324 for biofilters and activated sludge from a municipal wastewater treatment plant for the BTF. Inlet loads (ILs) between 10 and 45 g m-3 h-1 and empty bed residence times (EBRTs) from 30 to 120 s were applied. At inlet concentrations ranging between 200 and 400 mg Nm-3, removal efficiencies between 70 and 95% were obtained in the 3 bioreactors. Maximum elimination capacities (ECs) of 81 and 39 g m-3 h-1 were obtained…
Removal of pharmaceuticals from municipal wastewaters at laboratory scale by treatment with activated sludge and biostimulation.
2017
Abstract Municipal wastewater containing 21 pharmaceutical compounds, as well as activated sludge obtained from the aeration tank of the same wastewater treatment plant were used in lab-scale biodegradation experiments. The concentrations of pharmaceutical compounds were determined by high-performance liquid chromatography coupled to Orbitrap high-resolution mass spectrometry and ranged from 13.2 ng/L to 51.8 μg/L. Activated sludge was characterized in the terms of phylogenetic and catabolic diversity of microbial community, as well as its morphology. Proteobacteria (24.0%) represented the most abundant phylum, followed by Bacteroidetes (19.8%) and Firmicutes (13.2%). Bioaugmentation of was…
Biological nitrogen removal from landfill leachate: a pilot-scale study
1999
A pilot-scale two-stage process including an anaerobic pretreatment (up-flow anaerobic sludge blanket, UASB) unit and a pre-denitrification activated sludge process was studied for treating leachates from a municipal landfill (waste aged 4 to 5 years, area 2.5 ha) and from a windrow composting area (1ha). A single-stage pilot process was used for nitrification studies. The leachate characteristics were as follows: COD 740 to 2400 mg 1-1 (chemical oxygen demand), BOD7 (biochemical oxygen demand) approximately 1000 mg 1 -1, Ntot 40 to 120 mg 1-1 and the temperature was between 2 and 21°C. The results show that 45 to 50% COD removal could be achieved in the UASB reactor even at temperatures b…
Anaerobic and sequential anaerobic-aerobic treatments of municipal landfill leachate at low temperatures
1996
Abstract Anaerobic treatment of municipal landfill leachate (COD 1–4 g l −1 , NH 4 -N c. 0.16 g l −1 ) was studied at 11 and 24°C by using laboratory-scale UASB and hybrid reactors. Aerobic post-treatment of the anaerobically treated leachate was also studied at 24°C using an activated-sludge process. In the 11°C reactors, a COD removal of up to 60–65% was obtained with 1.5-2 day HRT and 0.7-1.5 kg COD m −3 day −1 organic loading rates. At 24°C, a COD removal of up to 75% was achieved with a 10 h HRT. The highest organic loading rate applied was 10 kg COD m −3 day −1 at 24°C. Inorganic material accumulated in the reactor sludges at both temperatures. However, the specific methanogenic activ…