Minute electric field reduced membrane fouling and improved performance of membrane bioreactor

Effective application of a low voltage and low intensity electric field in EMBR (a membrane bioreactor attached with electric field) may reduce fouling, energy consumption, while enhance treatment efficiency. For that, electrodes and membrane modules were re-arranged in EMBR to maintain constant electrophoresis forces against deposition/adsorption of extra-cellular polymeric substances (EPS) or sludge particles on the membrane. The copper wire cathode inside a flat membrane module and stainless steel mesh anode outside the module were effectively used in fouling reduction in treating simulate municipal wastewater. The applied electric field significantly enhanced the permeate flux of polypropylene (PP) non-woven (0.036 V/cm, extended the operating cycle 7 days) or polyester membrane (0.073 V/cm, 1.2 times), reduced sludge EPS production and membrane fouling, extended the filtration cycle and enhanced sludge activity. The irreversible membrane fouling was effectively reduced.

► Electrostatic repulsion and electrophoresis were effectively applied in reducing fouling.
► Extra increase of 2–8 × 10−3 kWh/m3 achieve 20–25% flux enhancement and 20 times reduction of filtration resistance.
► The electric field inhibits the secretion of extracellular polymeric substances (EPS).
► The activity of sludge was enhanced by the minute electric field.