Study On Sewage Treatment Technology Of Small Towns Based On Unsteady Water Inflow

For small-scale sewage treatment facilities and equipment with large changes in water quality and quantity of water,it is necessary to set up a regulating tank with a large tank capacity for water volume adjustment,resulting in a prominent problem of investment in large-scale sewage treatment and a significant increase in operating costs.Therefore,this study is aiming to propose a small-scale urban sewage electrochemical-biofilm combined treatment technology and equipment for water inflow,focusing on the influence of current intensity,plate spacing and HRT on the phosphorus removal efficiency of electrochemical system;The effects of packing density,operating conditions,HRT and DO on the denitrification efficiency of lightweight filler biofilm systems were systematically investigated.The 16S rDNA Amplicon high-throughput sequencing was used to study the microbial population structure and dominant functional genus of the system,and the mechanism of nitrogen removal was discussed.On this basis,the dephosphorization and denitrification efficiency of the electrochemical-lightweight biofilm composite system was investigated under the condition of unsteady water inflow.The main conclusions of the study are as follows:The current intensity,plate spacing,and HRT had significant effects on the phosphorus removal efficiency of the system.As the current intensity and HRT increased,the system's phosphorus removal efficiency increased,and the current efficiency decreased.As the plate spacing increased,the system's phosphorus removal efficiency and current efficiency increased first and then decreased.The results of response surface test showed that HRT had a significant effect on the phosphorus removal efficiency of the system.The current intensity and plate spacing had significant effects on the phosphorus removal efficiency of the system.The influence degree of each factor was:HRT>current intensity>plate spacing.When the electrochemical dephosphorization pilot system was in the unsteady flow rate,the reactor operated in continuous flow mode under the optimal conditions of current intensity 2A,plate spacing 15cm,HRT 2h⁵h.During the peak flow period,the most unfavorable hydraulic retention time of the reactor was 2 h.At this time,the TP concentration of the system effluent was 0.46 mg/L,and the TP removal rate was90.8%.HRT and DO had significant effects on the denitrification efficiency of the lightweight filler biofilm system.When Lightweight filler biofilm system was in the unsteady flow rate,the reactor operated under the reactor temperature 20±5°C,the cycle operation condition inlet water aeration?2h⁸h?-instantaneous drainage,DO 5-6mg/L.The maximum peak flow rate of unsteady water inflow occurred,and the shortest unfavorable hydraulic retention time of the reactor was 2h.At this time,the effluent COD,NH₄⁺-N,and TN concentrations were 29.6 mg/L,4.92 mg/L,and 9.26 mg/L,respectively.The removal rates were 90.0%,87.8%,and 78.0%,respectively.When the electrochemical-lightweight biofilm composite system was in the unsteady flow rate,the electrochemical unit operated in continuous flow mode under the reactor temperature20±5°C,current intensity 2A,a plate spacing 15cm,HRT 2h.the electrochemical unit operated.The biofilm reactor operated in intermittent flow mode under the cycle operation condition inlet water aeration?2h⁸h?-instantaneous drainage,DO 5-6mg/L.The maximum peak flow rate of unsteady water inflow occurred,and the shortest unfavorable hydraulic retention time of the reactor was 2h.At this time,the concentrations of COD,NH₄⁺-N,TN and TP in the system effluent were 32.6 mg/L,4.94 mg/L,9.49 mg/L and0.27 mg/L,respectively.The removal rates were 89.1%,87.7%,77.5%,and 94.6%,respectively,which can reach the Class A standard of the“Emission Standards for Pollutants in Urban Sewage Treatment Plants”?GB18918-2002?.The results of 16Sr RNA Amplicon sequencing showed that the dominant genus Nitrifying bacteria in the light-filled biofilm denitrification system mainly belonged to Enterobacter and Acinetobacter,and the denitrifying functional genus mainly consisted of Flavobacterium and Plexus.Cymmonadaceae_unclassified,Saccharibacteria;heterotrophic nitrification-aerobic denitrifying bacteria Pseudomonas,Rhizobium sp;influent mode had significant effects on the bio-population structure of the light-filled biofilm system,under unsteady water conditions,the biodiversity of the system and the relative abundance of the system change...