| With the rapid development of the Three Gorges Reservoir economy, the level of intensive producing of its pillar business pickle is getting higher, its scale is getting larger and larger with more and more producing enterprises. But organic wastewater with high concentration of salt and nitrogen from some pickle processing enterprises is discharged directly without effective treatment, as a result, the ecosystems of many rivers in the Reservoir are facing a real danger, and the life of local inhabitants is caused tremendous harm.In response to the features of low treatment efficiency of wastewater with high concentration of salt and poor activated sludge sedimentation, microorganism in Microbial bioreactor is difficult to gather, wastewater and mud in Secondary settling tank is not easy to Separate, the paper took a good use of good advantages of MBR process, which can gather in large numbers of microorganisms and can be unaffected by sludge sedimentation, and the tests were carried out to study on MBR treating pickle wastewater choosing the representative pickle wastewater as research object. It's mainly to reveal the removal efficiencies of MBR treating pickle wastewater, the effects of salting on membrane critical flux and the control of membrane fouling and cleaning ways, when MBR was used to treat pickle wastewater by studying the removal efficiencies of organic pollutant under the different membrane material and different treating process. A mathematic model of membrane critical fluxes is established to provide theoretical foundations for preventing membrane from fouling, determining fouling membrane cleaning method, reducing energy demands of treating industrial wastewater by MBR and improving treatment efficiency. The contents and main results of the paper are as the follows:①Pickle wastewater was treated by aerobic membrane bioreactor. In response to the features of low treatment efficiency of wastewater with high concentration of salt and poor activated sludge sedimentation, four groups of experiments were designed to study on treating pickle wastewater by mixed MBR using PVDF and PP membrane. On the condition of different feed loadings and normal temperature, and on the condition that the bio-film density was 15%, Salinity was 2%～3%,DO was 4mg/L～5mg/L, suction pumps were operated for 10 minutes and closed for 3 minutes, pressure gradient was 15KPa, compared on the removal efficiency of anaerobic tank effluent and the situation of membrane fouling of PP membrane and PVDF membrane, it's indicated that the best operating feed loading was 1.0KgCOD/(m3.d) for aerobic membrane bioreactor, and that the effluent concentrations of COD, NH4+-N and SS could meet the first class discharge standard of comprehensive discharge standard of sewage (GB8978-1996), TP is needed to discharge according to Standard by removal in Chemical methods; PVDF membrane modules could treat pillar wastewater more economically and effectively.②Pickle wastewater was treated by anoxic/aerobic membrane bioreactor. In response to the features of low TN removal rate by anoxic/aerobic membrane bioreactor, three groups of experiments were designed to study on treating pickle wastewater by mixed MBR using PVDF membrane. On the condition of different feed loadings and normal temperature, Salinity was 2%～3% and on the condition that the bio-film density was 15%, DO was 1mg/L and MLSS was 2000 mg/L in the anoxic zone, the bio-film density was 15%, DO was 4mg/L～5mg/L and MLSS was 6000 mg/L in the aerobic zone, the ratio of recycling the mixture was 200%, suction pumps were operated for 10 minutes and closed for 3 minutes, pressure gradient was 15KPa, by studying on removal efficiencies of organic pollutant and situation of membrane fouling, it's indicated that when the feed volume loading was 1.2KgCOD/(m3.d), the removal efficiencies of organic pollutant was the best, when the effluent concentrations of COD, NH4+-N and SS could meet the first class discharge standard of comprehensive discharge standard of sewage (GB8978-1996). Compared to Aerobic biofilm, the persent Removal of TN in Microbial bioreactor is improved 30%.③By analyzing the situation of membrane fouling when operating, it's indicated that salting-out could accelerate speed of membrane fouling, and that temperature was considered the main factor of effecting salting out, the lower the temperature was, the more salting-out would be, and the worse membrane fouling would be, and that adhering fouling membrane modules was mainly not reversible. The effect of the factors on fouling membrane was aeration strength > cease time > sludge concentration > pressure gradient between diaphragms. It's also indicated that the mathematic model of the effects of the above 4 factors on membrane fouling was:Y=-12.01+133.06A+3.14×10-4B+2.79C+1.07D-5.51×10-4AB-8.76×10-15AC-1.13×10-14AD-1.45×10-4BC-2.5×10-6BD+0.01CD-64.2A2+4.8×10-8B2-0.32C2-0.04 D2. By analyzing the model by Response Surface Method, it's the best operating mode was obtained, and it's when DO was 5mg/L, cease time was 3.24min, pressure gradient between diaphragms was 15.22KPa, sludge concentration was 6000mg/L. The cleaning methods of fouling membrane modules were also studied, and it's found that the air-water conbined backwash is the more effective way of physical cleaning, and that chemical cleaning was needed when the physical cleaning can't recovered effectively. Soaking in 0.5% HCl following 0.5% sodium hypochlorite was the most effective way of chemical cleaning, which could make the flux recovered with 82%.The research achievements of the efficiency and the control of membrane fouling of treating pickle wastewater by Mixed MBR Reactor would provide both a new technical route for the treatment of pickle wastewater with high concentration of salt, and would also provide scientific basis for spread and practice of treating pickle wastewater by Mixed MBR Reactor, which would be of important realistic significance.
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