Membrane fouling control and sludge solubilization using high voltage impulse (HVI) electric fields

• High voltage impulse (HVI) technique was examined to mitigate the membrane fouling in MBRs.
• HVI induction loosened the tightly deposited cake layer on membrane surface and eased its removal.
• HVI induction led to partial solubilization of the activated sludge.

The effectiveness of a high voltage impulse (HVI) technique in mitigating the membrane fouling occurring in membrane bioreactors was examined. After the activated sludge was membrane filtered, the cake layer was removed by either water-washing cleaning (experimental control) or HVI cleaning. The flux recoveries after HVI induction were always higher than those of the control. The effect of HVI induction on the sludge properties was also examined. The mixed liquor suspended solids (MLSS) concentration decreased with increasing HVI contact time, while the concentrations of soluble-chemical oxygen demand (SCOD), -total nitrogen (TN), -total phosphorus (TP), -polysaccharide, and -protein in the bulk solution increased, indicating that the flocs and cells were damaged by the HVI induction. These results suggest that the HVI induction led to sludge solubilization, which loosened the tightly deposited cake layer on the membrane surface, hence allowing it to be easily dislodged from the membrane surface.