Effect Of Aeration Positions On Operation Characteristics Of A Submerged Membrane Bioreactor

Submerged Membrane Bioreactor(SMBR)is a kind of highly effective new reactor which combines with biological degradation and membrane separation, and is improved on the basis of inner lop air-lift bioreactor. In the application, the main problem of membrane fouling and energy consumption promoted the use of MBR. In this paper, it is proved that self-designed MBR using different aeration locations will help slow down membrane fouling with CFD simulation results. The main results are as follows:In this paper, upon comparing the performances of different membranes and the current research situation, the plat PVDF membrane bioreactor was chosen. The design of the membrane Bioreactor is mainly on the basis of Materials Conservation law. With the cell kinetics, the calculated effective volume is 21.1L, physical length, width and height were 300mm, 200mm and 400mm in actual size, respectively. Aeration pipes were vertically perforated, and aeration hole spacing is 60mmAccording to the continuity equation,the momentum equation,and the Standardκ-εequation for mixture,software Fluent is used to simulate flow regime in SMBR. The liquid circulation velocity and gas volume distribution in the whole reactor-downcomer and riser by simulation. The velocity of reactor-riser increased by 71.4% and the flow state also changed dramatically in vertical aeration pipe reactor. Linked with the results of simulation and experimental results, vertical aeration pipe was effectively to reduce the growth rate of transmembrane pressure.In vertical aeration, the average removal of COD, NH3-N, TP and Turbidity were 98.6%,55.91%,97.98%and 95.59%, respectively. The conductivity did not changed at all. Aeration at the bottom of the aeration pipe, the mean removal of COD, NH3-N, TP and Turbidity were 98.51%,37.54%,98.16%and 93.06%, respectively. The removal of Conductivity did not alter at all. In two operating condition, the transmembrane pressure increased with operating time gone. But transmembrane pressure was lower in vertical aeration than in bottom aeration. Transmembrane pressure varied slowly, which indicated that this reactor was conducively to reduce membrane fouling.Because of screening effect of microreactor, so based on porous model-screening mechanism, a micro-reactor was designed for sewage treatment. Length of micro-channel was 120mm, width of micro-channel was 0.3mm and depth of micro-channel was 0.5mm.Tablets of micro-reactor was 40. The average effluent COD concentration of 7.738 mg / L, NH3-N to 1.239mg / L, turbidity for 1.66NTU. The mean removal of COD, NH3-N and Turbidity were 96.90%,93.08% and 96.73%, respectively. The removal of Conductivity did not changed at all. The results showed that the microreactor and SMBR had similar removal ability of COD, NH3-N and Turbidity.It is testified that the design of a novel microreactor and SMBR is feasible.