Study on Operational Conditions to Minimize Membrane Fouling in Membrane Bioreactor (MBR) System for Wastewater Treatment-Preliminary Pilot Tests

In this study, effect of antiscalant usage on minimizing of membrane fouling due to high water hardness during wastewater treatment tests run by a pilot-scale membrane bioreactor (MBR) system. The membranes used in these studies were Kubota flat sheet MBR membranes made from polyethylene with a pore size of 0.4 micrometer. Preliminary tests were carried out with tap water for sixty days of operation. To investigate the applicability and the effect of antiscalant usage, four experiments (two experiments with tap water and two experiments with wastewater) were carried out and each experiment lasted for 29 days. The tests were carried out in the presence and in the absence of antiscalant. Fouling on MBR membranes was investigated by monitoring flux decline versus time. In tap water tests, unstable flux was observed initially then a flux decline due inorganic scaling. On the other hand, the flux was almost constant up to end of the experiment in the presence of antiscalant. During wastewater tests (in the absence of antiscalant), the flux decline was observed within ten days of operation while during wastewater tests in presence of antiscalant, the flux did not decline until twenty days of operation. The use of antiscalant did not influencethe efuent quality. According to the quality analyses results for MBR efuent, removal efciencies for COD, PO4-P, and total N were 95%, 98% and 40%, respectively. In addition,99% of total suspended solid rejection and 98% of color rejection were obtained in the presence or absence of antiscalant.