Membrane for both aeration and filtration in membrane coupled sequencing batch reactor: it`s effects on filtration performance

Abstract

MSBR using a membrane for both aeration and filtration (MA process) was designed to reduce membrane fouling and enhance treatment efficiency and compared with MSBR using a membrane for only filtration (BA process) regarding filtration performance and treatment efficiency. In both processes, more than 98 % of COD in the synthetic wastewater was removed, showing excellent treatment efficiency, but MSBR using a membrane for both aeration and filtration showed 2.8 times longer operation time than MSBR using a membrane for only aeration. MSBR using a membrane for both aeration and filtration had more small particles in mixed liquor, so it showed higher the specific cake resistance and the lower compressibility coefficient than MSBR using a membrane for only filtration. Nevertheless, MSBR using a membrane for both aeration and filtration showed longer operation time because air goes into the lumen of a membrane and out of the surface of a membrane in aerobic reaction step, so it gets rid of the cake layer on a membrane surface and in membrane pores. MSBR using a membrane for both aeration and filtration can be very effective to reduce membrane fouling and increase filtration performance. In order to compare the energy efficiency of the membrane module and the bubble stone diffuser, the transferred oxygen amount per unit energy was measured. The membrane module has higher gas transfer efficient than that of the bubble stone diffuser but needs higher power to supply air into the reactor. The energy efficiency of the membrane module is inferior to that of the bubble stone diffuser at all airflow rates. Thus, in case of using a membrane module, below the 0.4 LPM of airflow rate has to be used to get above 40% energy efficiency.