Study On The Influencing Factors Of Membrane Fouling In A Submerged Membrane Bio-Reactor

Membrane bioreactor is a newly effective process for water treatment. In comparison with the activated sludge system, the MBR has merits with respect to the complete removal of solids from effluent, organic removals, low excess sludge production and small land requirement. However, membrane fouling is a perdurable impediment during the application of MBR. Based on a submerged membrane bioreactor, this research studies the impact of operating parameters and characteristics of microbes on membrane fouling, pursue the fouling mechanism, and put forward some appropriate membrane control methods.(1) Operating parameters on membrane fouling: Select aeration intensity, sluge concentration, pump-stop ratio as the three factors, than design a three factors and three levels orthogonal experiment. Combined with single-factor analysis, study on the membrane fouling mechanism. This experiment showed that the operating parameters affect on membrane fouling in the following order: Aeration intensity>pump-stop ratio>sluge concertration. Aeration influence the membrane fouling through membrane scouring and its effect on the sludge particle size. The optimum operating parameters are: 1.6m3/h of aeration, 4500mg/L of sludge concentration, 9:2 of pump-stop ratio.(2) Microbial metabolites on membrane fouling: The study focused on the influence of EPS and SMP on membrane fouling. Analyze the relationship between EPS and sludge settling characteristics, EPS and mixture viscosity, and then study how the EPS impact on membrane fouling. In addition, do some quantitative analysis on the polysaccharide and protein, then study which is the main reason for membrane fouling in EPS. The experiment showed that, with the increasing concentration of SMP and EPS, the total filtration resistance is increased, and membrane fouling is accelerated. Compared with the SMP, EPS is the priority factor of membrane fouling. EPS influence the membrane fouling by influencing sludge settling characteristics and viscosity. Compared with the polysaccharides, the protein in EPS is the priority factor for membrane fouling.