Integration of bio-electrochemical cell in membrane bioreactor for membrane cathode fouling reduction through electricity generation

A new membrane bioreactor (MBR) was integrated with an inserted bio-electrochemical cell consisting iron anodes, microbes and conductive membrane cathodes modified by polypyrrole, which maintained all benefits of MBR and generated constant electrical potential for cathode membrane fouling reduction. The biochemical and chemical corrosion of the iron anode generated electrons as a chemical cell; the biofilm microbes on iron anode may also extract electrons from wastewater similarly like in a microbial fuel cell (MFC). This kind of bio-electrochemical membrane reactor (BEMR) generated ∼0.2 V cell potential under different conditions when a 100 Ω external resistor was used. The cathode accumulated negative charges and reduced filter cake on membrane surface greatly due to the rejection of foulants; the flocculating effect of Fe3+ from sacrifice iron anodes decreased the specific resistance of sludge. Comparing with a control test, only two times of physical cleaning was carried out during 25 days filtration in the first stage of test, while the control MBR required very frequent physical cleaning. Fouling reduction was realized using internally supplied electric field in this BEMR, and it is no longer necessary to use additional external electric energy and facility for fouling reduction with electric field.