The Effect Of Extracellular Polymeric Substances On Membrane Fouling In Submerged Membrane Bioreactor

Membrane Bioreactor, as a new technology for wasterwater treatment using membrane filter technology, have been widely used in wastewater treatment to achieve effulent quality. However, the higher energy consumption and operation fee restricted the large scale application. A lot of study show that membrane fouling is the main obstacle, membrane fouling leads to flux decline and extra membrane cleaning.In this paper, the submerged membrane bioreactor was adopated to investigate membrane fouling behavior. The relationship between activated sludge properties and membrane fouling is studied with statistical method, especially the EPS as the most significant biological factor responsible for membrane fouling is analysed. Because the activated sludge properties and microbial metabolism are influenced by the operational parameters, the aeration and influent loading are selected to investigate the effect on the activated sludge properties and membrane fouling. The main research conclusions are summarized as follows:(1) The activated sludge properties such as LB-EPS, TB-EPS, SMP,μ, Zeta and EPS adsorbed membrane surface had impact on membrane fouling, these factors responsible for membrane fouing were quantitatively analysed by SPSS software. Soluble EPS, Loosely bound EPS were the major factors leading to membrane fouling; membrane fouling resistance and zeta potential, viscosity(μ), SVI showed good linear correlations, the variations of zeta potential, viscosity and SVI were induced by Loosely bound EPS.(2) Aeration had an important impact on membrane fouling. Comparing to membrane fouling for the different aeration MBRs, membrane fouling included 2 stages in different aeration: in a period of beginning, the membrane fouling of the higher aeration was more serious than the lower aeration; the results were opposite in stage 2. The influence of aeration on LB-EPS was important but TB-EPS was not affected by aeration. LB-EPS, LB protein had strong positive effect on membrane fouling, and protein was the major pollutants.(3) The influence of influent loading on characteristics of the activated sludge and membrane fouling were investigated. The results showed that the membrane fouling of the higher influent loading was more seriously during the operating time; Different influent loading led to MLSS discrepancy, MLSS increased with increasing influent loading, which accelerated the membrane fouling rate, the influence of influent loading on LB-EPS was important but TB-EPS was not affected by influent loading.