Study On Denitrification Treatment Of Acrylonitrile Chemical Wastewater By Embedded Immobilized Microbial Technology

Acrylonitrile chemical sewage with characteristics of complicated compositions,various types of pollutants,and usually of high chemical oxygen demand(COD)and total nitrogen(TN)concentrations has been recognized as one type of highly toxic industrial wastewater."Water Pollution Prevention Plan of Action" put forward a clear reguLation of ten key industries,especially oil refining,fertilizer and other industries.Furthermore,it will ban production projects which seriously pollute the water environment before the end of 2016 Therefore,the treatment of acrylonitrile wastewater is difficuLt and the effective treatment of acrylonitrile wastewater is urgently required.Acrylonitrile sewage treatment plant with an area of about 4 × 361m3 and hydrauLic retention time for 20 h,the COD and TN removal rate were 2.4% and 8.77%,respectively,as well as the effluent TN was 101.9mg/L.Because of nitrate accounted for a large proportion of 99% in effluent water,the deficiency of denitrification treatment process lead to high concentration nitrogen.In this study,immobilized enriched denitrifying bacteria activated sludge technology was adopted to process acrylonitrile chemical wastewater.Isolation and identification of high efficiently denitrifying bacteria from active sludge was also studied.Immobilized denitrifying bacteria activated sludge(defined as 1,2,3)were obtained.A denitrification reactor and aerobic reactor with small-scale experimental device was designed and built in this research.The batch and continuous experiments of simuLated nitrogenous wastewater domestication was fistly investigated.Under the inlet TN of 120mg/L condition,the optimum parameter including C/N for 2.0:1,fill rate for 20% and HRT for 8h were achieved which ensure water total nitrogen was controlled in less than 10mg/L.The simu Lated domestication experiment provide optimum operating conditions for rapid determination of acrylonitrile chemical wastewater denitrification Study on different C/N value(0,0.3:1,0.4:1,0.5:1,1.0:1 or 1.2:1),hydrau Lic retention time(HRT,18 h,12h,10h),and operating mode(sequencing batch,continuous),the resuLts showed that when the filling rate was 20%,nitrogen ratio was 1.2:1 and HRT was 10 h,the acrylonitrile wastewater's total nitrogen in the effluent was less than 10mg/L as well as the total nitrogen removal rate was 95%.