Investigation of membrane fouling in an MBR and EC hybrid system

Wastewater treatment methods have been employed in order to minimize water pollution and to increase drinking water resources. Membrane bioreactor (MBR) process is the most effective and newest technique. However, the disadvantage of this method is frequent membrane fouling. To handle this challenge, the electrocoagulation (EC) technique was merged with MBR. Different range of mixed liquor suspended solid (MLSS) concentration of activated sludge was loaded into the reactor. The various current density (CD) and distance between electrodes were set. Trance membrane pressure (TMP) was measured to monitor the fouling variation and then the critical flux-TMP-time diagrams were plotted. Comparing with the MBR system, the hybrid of MBR-EC system showed lower fouling. Besides, with increasing CD and decreasing the space between electrodes, the fouling rate decreases due to the creation of bigger flocks. In the lowest distance of electrodes (1cm) and highest CD (40 A/m2), the critical flux increased 8LMH for activated sludge with 2000 MLSS, 12 LMH for 5000 MLSS, and 16 LMH for 8000 MLSS. But, the microscopic photographs indicate that activation of sludge decreases in a high CD. Therefore, we should choose an optimum range for CD. The EC method in a suitable range of CD and electrodes’ distance was the effective way for fouling control.