Study On The Novel Nitrogen And Phosphorus Removal Process Based On Denitrifying Phosphorus Removal

The discharge standards of effluent from sewage treatment plants in China are becoming more and more strict,and nitrogen and phosphorus removal performance of existing biological treatment technologies are limited.In this study,two novel denitrifying phosphorus removal processes with high nitrogen and phosphorus removal efficiency were developed.First of all,a novel denitrifying phosphorus removal process based on anoxic-oxic process（DPR-AO）and the theory of denitrifying phosphorus removal was designed.The performance of the DPR-AO process and the microbial community characteristics of each reaction tank were investigated.The results showed that the average effluent concentrations of chemical oxygen demand（COD）,total nitrogen（TN）,ammonia nitrogen（NH₄⁺-N）and total phosphorus（TP）were 14.76,9.98,0.37 and 0.78 mg/L,respectively;and the average removal rates were 95.85%,83.12%,99.37%and 87.13%,respectively.In each reaction tank of DPR-AO system,Thauera,Dechloromonas,Comamonas and Dokdonella were the denitrifying phosphorus removal microorganisms.The relative abundance of functional microorganisms were 10.68%-15.05%.In addition,based on the multistage anoxic-oxic process（MAO）,a novel MAO process with function of denitrifying phosphorus removal was designed.In this study,removal performance and microbial community of the DPR-MAO process under different internal return ratios were investigated.With the internal return ratios increasing from 100%to 200%,TN and TP removal efficiency were increased from 76.05%and 86.39%to 87.46%and93.42%,respectively.During period of stable operation,the average COD,TN,NH₄⁺-N and TP concentration in effluent were 7.07,9.04,0.34 and 0.49mg/L,respectively.Meanwhile,the average removal efficiecny of COD,TN,NH₄⁺-N and TP were 98.00%,87.46%,99.52%and 93.42%,respectively.The nitrogen and phosphorus mass balance analysis revealed that the denitrifying phosphorus removal performance could be enhanced by increasing the internal return ratio.In DPR-MAO system,Thiothrix,Candidatus Accumulibacter,Dokdonella,Thauera,Dechloromonas,Comamonas and Pseudomonas were the denitrifying phosphorus removal microorganisms.When the two internal return ratios were increased from 100%to 200%,the sum of relative abundance of the denitrifying phosphorus removal microorganisms increased by 4 times,and the relative abundance of Thiothrix was increased from 0.36%and 0.52%to 53.58%and 56.64%.In summary,the dominant position of bacteria for denitrifying phosphorus removal could be enhanced by increasing internal return ratios.Finally,compared with anaerobic-MAO process and UCT-MAO process,DPR-MAO process had excellent nitrogen and phosphorus removal performance.Nitrogen and phosphorus removal efficiency were 85.34%and91.34%,respectively.