Research On Carbon Source Utilization Via Denitrifying Nitrogen And Phosphorus Removal Process

Carbon source is the key to the efficiency of denitrification and phosphorus removal in the traditional biological wastewater treatment processes. Because the COD of urban water is generally low, so how to use the carbon source abundantly is the critical topic of the biological wastewater treatment technologies.This topic studied the characteristic about the usage of carbon in the the denitrification and phosphorus removal process to achieve to utilize the carbon source more efficiently, improving the A2N process by setting the pre-denitrification tank(Anoxic-A2N, A-A2N).The results show that:(1) At the low C/N conditions,the A-A2N system removed the main pollutants in domestic sewage stably and efficiently.The removal efficiency of COD, TP, TN was above95.29%,93.32%,78.83%respectively.And the effluent can meet the primary standard of " Discharge standard of pollutants for municipal wastewater treatment plant"(GB18918-2002).(2)The A-A2N system achieved to distribute the carbon optimally, and enhanced to use of the carbon efficiently.The portion of the total carbon in the anoxic stage owned61.16%. but the aeration stage was only10.03%.(3)Through the research,some engineering significant parameters were obtained,as follows:MLSS was2936mg.L-1; HRT of the pre-denitrification tank was0.5h;HRT of the anaerobic tank was1.5h;the ratio of the returned sludge was40%.(4)Compared to the A2N system,the A-A2N system had more efficiency toward the anaerobic stage,and the decreased COD of it possessed82.61%(by mass).Among it, the quality of COD synthesized into PHB by DPBs, the quality of adsorbed into the activated sludge, The quality of microbial degradation for life activities accounted for55.37%,18.72%,7.92%,respectively.(5) The anoxic stage of the A-A2N system realized the usage of the carbon efficiently. It had the three forms of usage-carbon which involves internal carbon, adsorbed carbon, carbon in the sewage wastewater, the utilization condition was97.74%,82.27%,96.78%, respectively. Simultaneously, the consumption of the three forms of carbon had some quantitative relationship between the quality of nitrogen and phosphate in the process of the denitrification and phosphorus removal,which had studied in this reseaarch.(6) The dynamic model of the utilization of the carbon source in the process of the denitrification and phosphorus removal of the A-A2N system was derived, based on the Monod equation.This topic found the characteristic of the usage carbon in the denitrification and phosphorus removal process, getting the feature of the transition and usage about the different carbon, building the relation of the carbon utilization and the quality of the removed pollutants,and achieving the efficient usage of the carbon in the wastewater.