| A novel AOD-MBR, a perfect combination of the membrane filtration and the activated sludge process, was used for domestic wastewater treatment in this research, It can reduce energy consumption and membrane fouling, comparing to the traditional MBR process. This study aims at providing a theoretical support for the new AOD-MBR process to be used in engineering application, such as exploring the optimal operation conditions which reduce membrane fouling and increase the nitrogen removal,, choosing an appropriate membrane module according to the process conditions. During the experiment, from preparation of experiment to sludge domestication and the stable operation of the reactor was80days, the parameters, including HRT, MLSS,and aeration intensity, were changed during100days operation period. Water quality, membrane flux, sludge characteristics, membrane resistance, and other parameters under different conditions were meausured to investigate the influence of the operating conditions and the sludge features on the treatment efficiency and the membrane fouling. The concentration of proteins and polysaccharides in mixed solution and cake layer were measured. The relationship between the fouling resistance and the composition of sludge was discussed. Two membrane modules, i.e., hollow fiber membrane and flat membrane, were compared in AOD-MBR process on the flux decling, treating efficiency, and permeate quality.Some conclusions were made as follows:(1) During the experiment, the permeates of the two membrane modules are satisfactory. The membranes play an important role in retenting the organic matters. Overall, COD、 NH3-N(mg/L) and TN removal of flat membrane are better than that of hollow fiber membrane..(2) By analyzing membrane flux decling, the higher the initial flux is, the sooner the flux decays. The hollow fiber membrane has a higher flux declining rate than flat membrane. As for the membrane resistance, the hollow fiber membrane is significantly higher than that of flat membrane. The resistance of cake layer of two membrane module accounted for more than96%of the total resistance。(3) The protein and polysaccharide and EPS/VSS values of hollow fiber membrane to be generally higher than the flat membrane cake layer and MLSS. EPS protein and polysaccharide to be largely above the SMP protein and polysaccharide. Hollow fiber membranes and membrane cake layer flat EPS and protein and polysaccharide film respectively and pollution are the two membrane showed similar strong correlation.There are some issues to be studied in further for this experiment:such as, simultaneous nitrification and denitrification optimization of control conditions, improved aeration equipment, flow pattern studies and sludge deposition problems. |
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