Effect of an electro phosphorous removal process on phosphorous removal and membrane permeability in a pilot-scale MBR

The pilot membrane bioreactor (MBR) was equipped with an electro-coagulation process for phosphorous removal (EPR process). The effect of the EPR process on nutrient removal and membrane permeability was investigated in this study. Experiments were carried out for about 5 months with the pilot MBR that treated wastewater at a capacity of 50 m(3)/day. And the MBR used two different materials of the plate type membrane: polyvinylidene fluoride (PVDF) and polyethersulfone (PES). Phosphorous ion released from the anaerobic settling tank was coagulated by electrochemical reaction with aluminum ion discharged from aluminum plate electrodes in the EPR tank. The phosphate (PO(4)(3-)-P) removal efficiency and the total phosphorous (TP) removal efficiency by electro-coagulation were 89.2% and 79.9%, respectively. Results of particle size distribution (PSD) analysis showed that the particle sizes of flocs were mostly in the range of 50-150 mu m, and the membrane resistance decreased significantly in the MBR as the EPR proceeded. Consequently, this study showed that the EPR process was useful for reducing trans-membrane pressure (TMP) and for removal of phosphorous in the MBR, which was operated in long sludge retention time (SRT) conditions. (C) 2009 Elsevier B.V. All rights reserved.