Effect of bio-electrochemical systems on the removal of organic and inorganic membrane fouling from anaerobic membrane bioreactors

To alleviate the fouling of membrane bioreactors, a coupling system was constructed in which a conductive membrane served as the anode of a bio-electrochemical system, whereas ordinary carbon felt served as the cathode. The membrane module showed approximately 90 % performance for wastewater chemical oxygen demand removal. As the external resistance increased from 50 to 1500 Ω, the number of operating days increased from 25 to 62. The respective concentrations of polysaccharide and protein on R-1500 membrane surface were 6.81- and 2.05-fold greater than the concentrations on the R-50 membrane, and the concentration of Ca2+ on the surface of the R-50 membrane was 1.48-fold greater than the concentration on the R-1500 membrane. Therefore, inorganic fouling is the main type of membrane fouling in coupled systems with low external resistance. For coupled systems with higher external resistance, severe organic fouling eventually causes membrane blockage. Variance partitioning analysis showed that the micro-electric field contributed to 95.34 % of the effect on the control of membrane fouling, significantly greater than the 67.19 % contributed by the current. Therefore, in the system where organic and inorganic fouling coexists, appropriate enhanced field strength (increase in external resistance) is particularly important for membrane fouling control.