Study On Hybrid Anaerobic-chemical Precipitation-a/o Process In Treating Organic Amine Wastewater

The organic amine wastewater,which was discharged from Jiangshan Chemical, had high concentration of total nitrogen and large change in concentration,contain a quantity of toxic and harmful substances.Original sewage treatment system existed many problems,such as limited capacity,effluent failing to reach standards,and high runing expense.hybrid anaerobic-chemical precipitation-A/O combined process is proposed to reconstruct original process in this text.Treatment effects of each unit are studied in treating organic amine wastewate in the laboratory.Suitable operation conditions and operating parameters of each section are determined,In addition,this process is tentatively used in practical project.Hybrid anaerobic reactor is used as pretreatment,in which granular sludge is successfully cultivated and reactor started smoothly through 73 days at normal temperature.Optimal HRT and volume load is 1.85d and 1.543～2.701kgCOD/(m³·d),removal rate of COD can keep about 50%,conversion of organic amine also maintain above 60%,meanwhile,B/C value of raw water is increased from 0.263 to 0.362 by anaerobic digestion,which create favorable conditions for further biochemical treatment.MgCl₂·6H₂O and Na₂HPO₄·12H₂O are used as precipitant to remove ammonia nitrogen in chemical precipitation,various influencing factors are studied on ammonia nitrogen removal rate and phosphate utilization ratio,for example,pH,n(P):n(N),n(Mg):n(N) and initial ammonia nitrogen concentration.The optimal parameters are obtained through multi-index orthogonal test and single factor optimizing test, optimal pH is 9.5,optimal n(Mg²⁺):n(NH₄⁺):n(PO₄^3-) is 1.2:1:1.1,in which ammonia nitrogen removal rate is 90.81%,phosphate utilization ratio get to 97.34%,moreover remaining phosphorus amount is only 27.67mg/L.A/O process is used as subsequent treatment,optimal operation conditions are determined as follow:pH is between 7 and 8,DO of A section is below 0.5mg/L,DO of O section is above 4.0mg/L,water temperature is 25℃.optimal operating parameters are determined as follow:total HRT is 30h,HRT of A section is 7.5h,HRT of O section is 22.5h,SRT is 30d,R(internal ratio reflux ratio) is 3.0.Design scale of practical project is 1000m³/d,design volume load of hybrid anaerobic reactor is 2kgCOD/(m³·d),HRT is 44.5h,the ratio between packing layer and sludge layer is 5:2.Forepart of pre-aeration tank blow off ammonia nitrogen and pollutant by aeration stripping,posterior segment is aeration-flocculation tank,flocculation time of design is 20min.total HRT of A/O is 32h,HRT of A section is 8h,HRT of B section is 24h.internal ratio reflux ratio is 300%,sludge reflux ratio is 50%.Through about 100 days′commissioning,the project could run normally.even when average influent concentration of COD and total nitrogen were 3973mg/L and 810mg/L,the combined system total removal rate of COD and BOD were 90.8%and 97.04%respectively,average effluent concentration of ammonia nitrogen were below 50mg/L.In addition,it is also quite effective to remove petroleum,volatile phenol,sulfide,cyanide.All adequately prove that hybrid anaerobic-chemical precipitation-A/O combined process is suitable for treating organic amine wastewater,it also provide strong reference for treating other analogous wastewater and has some popularization value.