Bio-phosphorus Removal From Mixed Municipal Sewage By Multi-point Enhanced Oxidation Ditch Process

With the rapid development of urbanization and industrial parks, urban sewage treatment plant water collection showing a trend of more and more obvious "hybrid urban sewage, industrial waste water is about60%to80%, sewage is about20%to40%, and the proportion of industrial wastewater or will further improve. Mixed urban sewage water quality complex composition, the influent load fluctuations, low C/N and B/C value, using the traditional biological treatment process, the effect of phosphorus and nitrogen removal is generally poor.Hydrolysis acidification-anaerobic-modified Carrousel oxidation ditch combination of multi-point intensive oxidation ditch process, through the regulation of pre-hydrolysis acidification, oxidation ditch hydraulic retention time regulation, secondary sedimentation tank sludge return ratio control and other multi-point intensive period of one years of mixed city phosphorus removal from wastewater in the pilot study. Mixed urban sewage taken from a sewage treatment plant in Zhengzhou two aerated grit chamber, since the high water tank in turn by hydrolysis acidification tank, anaerobic tank, modified Carrousel oxidation ditch and secondary settling pond, pool acid hydrolysis provided with a one-piece the mud precipitate reflux device, hydrolysis acidification tank sludge reflux; improved oxidation ditch designed to improved eight corridors, and dramatically increase the the single corridor aspect ratio, the bottom internal part of the locale microporous aeration and adjustable.Optimization of operation parameters results show that:hydrolysis acidification of water force retention time (HRT)3h, anaerobic pool HRT4h, modified Carrousel oxidation ditch HRT11h, sludge recycle ratio (R)1, COD and phosphorus removal. When the influent pH between6.8and7.5, each reactor water temperature of about14to30℃, water COD, BOD5, NH3-N, TN, TP the average concentration of557mg/L,143mg/L,29mg/L,40.1mg/L and5.9mg/L, total hydraulic retention time of17.5h, sludge reflux ratio of1, the average DO control in the2to4mg/L and no external carbon source and alkalinity conditions, the effluent COD,BOD5, NH3-N, TN, TP the average concentration of54.9mg/L,6.1mg/L,2.8mg/L,12.6mg/L and0.91mg/L, on the COD, BOD, NH3-N, TN TP average removal rate reached90.1%, 95.7%,90.3%,68.6%and84.6%. Key water quality indicators are stable up urban sewage treatment plant pollutant discharge standards "(GB18918-2002) A standard.Perennial test run, the process efficiency, stable and reliable, and less affected by seasonal changes, can be used as the preferred process of the existing municipal wastewater treatment plant mentioned standard transformation.