Optimized coupling of an intermittent DC electric field with a membrane bioreactor for enhanced effluent quality and hindered membrane fouling

This article studies a submerged membrane electro-bioreactor (SMEBR), an integrated system embracing biological treatment, electrical coagulation, and membrane filtration, all in one individual reactor, by applying an alternating electric field to a membrane bioreactor (MBR). The alternating electric field has been applied with current densities ranging from 5 to 23 A/m2 under eight different electrical exposure modes. The results indicate that under the optimum condition with a current density of 12.5 A/m2 and an exposure mode of (415 s OFF-185 s ON), the COD and phosphate removals would be respectively 4% and 43% more compared to an unmodified MBR system. Also at the same current density but with an exposure mode of (496 s OFF-104 s ON), ammonia removal efficiency was 22% more than the MBR system. At lower current density of 5 with an exposure mode (400 s OFF-200 s ON), the amounts of polysaccharides and proteins were respectively 59% and 51% less than ordinary membrane bioreactor. In summary, the SMEBR reactor membrane fouling is hindered while filtration course and particle size increase. Moreover, at current density less than 20 A/m2 sludge activity enhances.