ANAEROBIC BIOREACTOR WITH IMMERSED MEMBRANE–PERFORMANCES AND MEMBRANE FOULING

摘要

This study focuses on an anaerobic membrane bioreactor with an immersed membrane (IManBR) for wastewater treatment. Experiments were performed at lab scale with synthetic wastewater under psicrophilic conditions (temperature=20 °C) during 280 days. TOC and COD removals between 86 and 95% and between 87 and 90% were reached at organic loading rates of 1.5 kg COD/m~3.d. rnExperiments were performed using short filtration steps followed by long relaxation steps, and without backwashes. Some simple rinsing steps with pure water were also used and their efficiency to enhance the permeate flux was demonstrated. However a non-reversible fouling was also obtained, that can be characterized by an average loss of permeate flux obtained after rinsing of 0.09 l/m~2.h/d. rnThe influence of COD removal and accumulation of volatile fatty acids on the in-situ critical flux was studied. analysis of the dynamic comportment of the bioreactor after increases in organic loading rates allowed to establish a relationship between the critical flux and the concentration in volatile fatty acids (VFA), which is enhanced when the methanogenic activity is the limiting kinetic step of the biological process. This study points out that a good methanogenic activity is necessary to guaranty the removal of organic removal and also to limit membrane fouling.