Search results for " FOULING"
showing 10 items of 79 documents
Fouling mechanism elucidation in membrane bioreactors by bespoke physical cleaning
2018
Abstract Cake layer deposition on a membrane surface can determine both external and internal membrane fouling through negatively affecting the total filtration resistance while exerting a positive effect as a pre-filter. Membranes are usually subjected to a periodic cake layer removal through routine physical cleaning, specifically permeate backwashing of hollow fiber membranes, or enhanced cleaning through, for example, chemically-enhanced backwashing. Physical cake layer removal is crucial for sustaining permeability, yet the effect of different physical cleaning modes remains poorly evaluated. The present work attempts to analyze physical cake layer removal through the application of sp…
Multistage recovery process of seaweed pigments: Investigation of ultrasound assisted extraction and ultra-filtration performances
2017
International audience; The objectives of this study were first to evaluate the performance of seaweed pigments’ recovery through ultrasound assisted extraction (UAE) and ultra-filtration (UF), and second to investigate the membrane fouling mechanism and evidence the threshold flux during filtration. The pigments’ recovery from the extract was performed using 5 kDa and 10 kDa ultra-filtration membranes. Results showed that increasing the extraction temperature in the range of 40–60 °C was proportional to chlorophyll extraction efficiency, while the maximal carotenoid yield was achieved at 50 °C. Ultrasonic power (from 100 W to 300 W) facilitated the extraction of both chlorophylls and carot…
Biological nitrogen and phosphorus removal in membrane bioreactors: model development and parameter estimation
2012
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…
Long-run operation of a reverse electrodialysis system fed with wastewaters.
2018
The performance of a Reverse ElectroDialysis (RED) system fed by unconventional wastewater solutions for long operational periods is analysed for the first time. The experimental campaign was divided in a series of five independent long-runs which combined real wastewater solutions with artificial solutions for at least 10 days. The time evolution of electrical variables, gross power output and net power output, considering also pumping losses, was monitored: power density values obtained during the long-runs are comparable to those found in literature with artificial feed solutions of similar salinity. The increase in pressure drops and the development of membrane fouling were the main det…
Comparison between moving bed-membrane bioreactor (MB-MBR) and membrane bioreactor (MBR) systems: Influence of wastewater salinity variation
2014
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…
Integrating functional traits into correlative species distribution models to investigate the vulnerability of marine human activities to climate cha…
2021
Climate change and particularly warming are significantly impacting marine ecosystems and the services they provided. Temperature, as the main factor driving all biological processes, may influence ectotherms metabolism, thermal tolerance limits and distribution species patterns. The joining action of climate change and local stressors (including the increasing human marine use) may facilitate the spread of non-indigenous and native outbreak forming species, leading to associated economic consequences for marine coastal economies. Marine aquaculture is one among the most economic anthropogenic activities threatened by multiple stressors and in turn, by increasing hard artificial substrates …
The fouling phenomenon in membrane bioreactors: model description and strategies for energy saving
2015
Membrane fouling represents one of the major crucial issues for membrane bioreactor (MBR). Membrane fouling and high aeration requirements (for inducing shear stress to limit fouling) make MBR operation economically demanding due to high energy costs. Although several studies on MBR fouling have been performed, a comprehensive knowledge on how to reduce membrane fouling and consequently energy saving is still lacking. Two scenarios are analyzed and compared each implementing different operating conditions. As expected, MBR operation at low air flow rate (qa) leads to a substantial reduction of the operational costs (namely, 20% respect to the suggested manufacturers ones in terms of qa).
Performance of a MBR pilot plant treating high strenght wastewater: analysis of biomass activity and fouling behaviour
2012
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…
Influenza dei polimeri extracellulari sul fouling e sul foaming negli impianti MBR.
2009
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…
New applications in integrated fixed film activated sludge-membrane bioreactor (IFAS-MBR) systems
2020
Abstract This chapter provides an overview on the development and application of integrated fixed film activated sludge-membrane bioreactor (IFAS-MBR) systems. IFAS-MBRs represent a novel configuration for advanced wastewater treatment, and only a few studies are available in literature. With this aim, the results of some studies on IFAS-MBR systems already published are discussed and compared in this chapter. Literature shows that the influent carbon to nitrogen ratio (C/N) strongly affects the biological process in IFAS-MBR. The organic matter removal efficiency (removed biologically) decreases from 60% to 23.5% with the decrease of influent C/N from 10 to 2 mgCOD mgTN− 1. Nitrogen remova…