Influence of Bacterial Growth on SMP Production and Consequent Membrane Fouling of Fouling Causing Bacteria

摘要

Membrane biofouling has been a major obstacle for wide utilization of membrane bioreactors (MBRs) due to the frequent cleaning and replacement of fouled membranes, mainly caused by microbial byproduct, consequence of increasing waste water treatment cost. In this study, we investigate the influence of growth of fouling causing bacteria (FCB) at different dilution rate on the production of soluble microbial product (SMP), regarded as main foulant, causes to severe membrane fouling potentials. Bacterial strain closely related to Mesorhizobium ciceri (98.5%) was isolated from pilot scale MBR treating municipal waste water and characterized as severe FCB. The growth performance of FCB was investigated in Chemostat in combination with laboratory-scale cross flow membrane filtration system (CFMFS). Bacterial cell number, transmembrane pressure, total SMP, extracellular polymeric substances (both loosely and tightly bound) and fouling potential showed increasing trend with dilution rate from 0.05 h~(-1) to 0.6 h~(-1). For clear understanding of SMP production by FCB, MFC (microbial fuel cell) reactor was operated with exoelectrogenic FCB closely related to Klebsiella pneumoniae (99.5%) under anoxic condition without oxygen supply as a source of electron acceptor. The study revealed that under anodic respiration condition FCB able to mitigate membrane fouling by less SMP production.