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In traditional wastewater treatment process, because the contradiction of the carbon sources, sludge age and nitrate paradox, particularly in the treatment of the domestic wastewater of low C/N ratio, carbon source shortage problem in phosphorus and nitrogen by that is particularly difficult. Because the chemical phosphorus removal is effective, so how to solve the bio-denitrification problem more effectively is imminent. Based on the traditional step-feed of activated sludge process, through dosing suspended packing into aerobic pools, strengthen the effect of nitrification and improve denitrification effect, for efficient sewage denitrification provides a new concept.The results showed that:(1) Suspension packing can strengthen the traditional method of activated sludge nitrification-denitrifying effect. Along with the packing rate increased, NH3-N removal rate of aerobic pools rised, water average NH3-N concentration of0.25mg/1, NH3-N removal rate around99.5%in the basic stability; The system also presented the same increasing trend of TN removal rate, the highest removal rate was80%, TN removal rate increased by9%compared with no packing,the best packing rate was65%.(2) Along with the packing rate increased, nitrification rate in three paragraphs were also increasing, three sections of average rate of nitrification with packing of15%,50%,80%were increased by50.9%,90.7%,118%.(3) Along with the increase of dissolved oxygen in aerobic pools, NH3-N removal rate was rising, but the removal of TN raised first then reduced. When DO=4.0mg/1, this time the system was more apparent SND phenomenon, and the higher ratio carbon and nitrogen, simultaneous nitrification denitrifying phenomenon more obvious, TN removal rate was more higher accordingly.(4) Most carbon source in the system removed in anoxic pools,70.95%for removal. It contained three parts,75.67%was as denitrifying carbon sources, used for cell synthesis of19.67%, and a small part was adsorption carry by sludge, embodies the carbon sources of efficient use in the step-feed mud-membrane process.(5) The step feed mud-membrane process is suitable for variety microbial growth to breed: advantage bacterium of original sludge samples is14only, while the system runs stably, microbial richness have improved. The advantage bacterium of activated sludge samples is up to20kinds, and biological membrane samples strains can achieve26kinds. The similarity of original sludge and microbial community of system is only31%, microbial community of active sludge and the biological membrane of packing also has the obvious differences, the similarity is only35%.(6) The bacteria number of three anoxic pools, aerobic pool are significantly decrease. The more bacteria, the higher the rate; the less, the rate is lower, the system rate of (denitrifying) nitrification and number of (denitrifying) nitrifying bacteria are positively related.
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