Study On The New Biological Nitrogen Removal Process Of OAA-SBR For The Low C/N Ratio Of Rural Wasterwater

Face the grim problem of water pollution and water resources crisis, at present,torealize the advanced wastewater treatment and the wastewater reutilization have becomethe important task for water treatment workers, especially, the depth removal of ammonianitrogen and phosphorus is the most prominent and critical. In this thesis, in order to saveof energy (aeration) and COD,and less sludge production，inverted A2O technology andSBR technology which in the activated sludge process were intergrated to produce a newkind of the preaeration and anoxic/anaerobic/intermittent aeration denitrogenation processused in the wastewater of low C/N ratio,which is named OAA-SBR（xide/Anoxic/Anaerobic-Seguencing Batch Reactor）or PAAI（the Preaeration andAnoxic/Anaerobic/Intermittent Aeration Process）process. Experiments were carried out todispose the wastewater of low C/N ratio in OAA-SBR experimental device designed byapplying analogue theory.In order to accelerate the investigation development of OAA-SBR process,inparticular to accelerate the application of OAA-SBR process for the low C/N wastewatertreatment,the research fed with municipal wastewater in dry well,and the effect of differentoperational factors and influent characteristics on the OAA-SBR system at intermittentoperation were studied systematically.Firstly, the preaeration and OAA-SBR process was use to treat low C/N domesticwastewater in this study,then contrasted the removal efficiency.Hydraulic retention time(HRT) requirements for the process and effects of HRT on the nitrogen removalperformance were investigated.Meantime, the change law of pH and the concentration ofpollutants under the optimal HRT condition were analyzed. It was found that theappropriate increase of the ratio of anaerobic reaction zone HRT to the system HRT wasbeneficial to COD and TN removal. When the reaction zone HRT ratio ofpreaeration/Anoxic/Anaerobic/Intermittent Aeration reaction zone was1:1:1:2, pollutantswere easier to be removed with the prolongation of HRT. When HRT of preaeration/Anoxic/Anaerobic/Intermittent Aeration reaction zones were2h/2h/2h/4h, the system wasin relatively optimum running status. The mean removal rate of COD and TN were92%and98%, respectively. The concentrations of pollutants had some relevance to pH in thereaction zone. In addition, the system has been running at low load, In addition, the systemhas been running at low load. SV and SVI values were low and stable during the entireoperation.In order to lucubrate the anti-shock loading capability of the new OAA-SBR processwas utilized to treat nitric wastewater,and the pollutant removal efficiency at low loadingrate of0.041to0.092kgCOD·kg-1MLSS·d-1and high loading rate of0.253to0.625kgCOD·kg-1MLSS·d-1was investigated.The results reveal that longitudinal level of loadhad influence on the activity of microorganisms in OAA-SBR system,and in differentloads,different microbial strains would obtain competitive advantage in the same reactor.OAA-SBR has a strong capability of anti-shock loading,and increased loading rate hasadvantage to the biological nitrogen removal of the system,and the average removalefficiencies of TN are88.8%and97.1%respectively,with the effluent TN of5.87mg/Land2.15mg/L. The removal efficiencies of COD are all more than90%at two loadingrates,with the average effluent COD of below39mg/L,which meets the first level Acriteria specified in the Discharge Standard of Pollutants for Municipal WastewaterTreatment Plant（GB18918-2002）.