Study On The Application Of Zero-valent Iron In Denitrification And Anaerobic Phosphorus Release Of Domestic Sewage

So as to improve the removal effect of nitrogen and phosphorus from domestic sewage b y traditional biological denitrification and dephosphorization,this stud y explores the effects of zero-valent iron（ZVI）coupled activated sludge s ystem on denitrification and anaerobic phosphorus release through adding ZVI into the traditional biological denitrification and dephosphorization s ystem.The detailed information on research results as following:Firstly,compared with a single ZVI s ystem and a single activated sludge s ystem,the coupling s ystem of ZVI+activated sludge has a better effect on NO₃^--N removal.ZVI can improve the NO₃^--N removal efficiency of anoxic denitrification s ystem.The TP released from the coupling s ystem in the anaerobic stage was between those in the single ZVI s ystem and the single activated sludge system.However,ZVI couldn’t improve the phosphorus release effect in the anaerobic stage,it had a positive effect on the phosphorus removal in the whole biological process of anaerobic and aerobic.Secondl y,this stud y explored the influence of different reaction conditions including the t ype and dosage of ZVI,p H,C/N on the denitrification efficiency of the coupling s ystem.The detailed information includes:（1）The addition of iron powder after pickling has a better effect on NO₃^--N removal,but the accumulation of NH₄⁺-N in the s ystem turns more.（2）The coupling s yst em has a better removal effect on NO₃^--N,and a lower accumulation of NO₂^--N and NH₄⁺-N under ZVI dosage with 2g/L,p H ranged from 6.5 to 7.5,and C/N with 6.Moreover,and this determined optimal condition can maintain the p H within the range of the normal growth of microorganisms.Thirdl y,the influence of different reaction conditions containing dosage of ZVI,p H,C/P on the phosphorus removal efficiency of the coupling s ystem was investigated in this study,the related information is as following:（1）compared with the s ystem without adding ZVI,the s ystem adding ZVI had a better removal effect of TP at the end of the aerobic stage.（2）The coupling s ystem has a better removal effect of TP under ZVI iron with 2g/L and C/P with 10,20 and 30.（3）The amount o f anaerobic phosphorus release in creased with the increase of p H,but the effluent TP concentration did not change with the change of p H in aerobic stage.Finall y,taking the actual domestic sewage as the treatment object,the SBR operation mode is adopted to discuss the denitrification and dephosphorization efficiency of the coupling s ystem for the actual domestic sewage.The research results show that:Both the coupled s ystem and the single sludge system have well removal effect of NH₄⁺-N.Furthermore,the coupled s ystem has better removal effect of TN,TP and COD _Cr than the single sludge s ystem.In the effluent of the coupling s ystem,the concentrations of NH₄⁺-N,TN,TP and COD_Cr can meet the Grade A standard of the（GB18918-2002）.In the effluent of the single sludge system,onl y the concentration of NH₄⁺-N can meet the Grade A standard of the（GB18918-2002）.Moreover,the sludge in the coupling s ystem is compact and spherical.In the single activated sludge s ystem,the sludge texture is loose and flak y.The removal effect of nitrogen and phosphorus in activated sludge s ystem can be effectivel y improved b y adding ZVI to the traditional biological nitrogen and phosphorus removal system.This stud y provides a new idea and technical reference for improving the nitrogen and phosphorus removal efficiency of traditional biological nitrogen and phosphorus removal process.