Study on membrane fouling of submerged membrane bioreactor in treating bathing wastewater

A pilot-scale submerged membrane bioreactor (MBR) was used to treat the bathing wastewater for more than 90 d. Several factorsaffecting membrane fouling were studied, including the variation in transmembrane pressure (TMP), changes in extracellular polymericsubstance (EPS), and distribution of membrane resistance (R). The relationships between R and EPS concentration were found to beR=0.00008(EPSs)2.915 in the mixed liquor (EPSs) and R=0.2853(EPSm)-0.824 on the membrane surface (EPSm). The constantresistance of the clean membrane (Rm), the resistance due to concentration polarization (Rp), the cake layer resistance (Re), and theresistance due to pore blocking (Ri), were 0.006%, 20.15%, 54.13%, and 25.72% of R, respectively. The results indicated that Rchad the greatest contribution to the total membrane resistance. The obtained membrane resistance model was R(t)=4.609×108(1+0.01t)0.5. Molecular-based methods (polymerase chain reaction-denaturing gel gradient electrophoresis (PCR-DGGE) and fluorescent insitu hybridization (FISH)) were used to study the bacteria attached on the membrane. The 16S rDNA gene sequence analysis suggestedthat certain phylogenetic group of bacteria, for example, Pseudomonas sp. And Nitrobacter sp., might have contributed to the formationof membrane on biofilms.