Study On Advanced Treatment For Sewage Of The G-Series High-Speed Train Station

In recent years,the rapid development of China railway high-speed(CRH)has caused rapid development of railway sewage treatment.Due to the high punctuality rate of high-speed railways and the small amount of passengers in the station area,the quality and quantity of domestic sewage in the high-speed railway station area are unstable,the ammonia nitrogen is high and the organic matter is low,showing low C/N ratio and water quality characteristics.The traditional biological treatment process used is limited,especially TN,TP can not achieve the Level A of "Discharge Standard of Urban Sewage Treatment Plant Pollutants"(GB18918-2002).Therefore,it is of great significance to research and develop new advanced treatment technologies that are suitable for the characteristics of domestic sewage in high-speed railway stations.This paper is based on the preliminary investigation of the characteristics of domestic sewage in station areas of CRH and the status quo of processing technologies.In view of the existing problems in the advanced treatment of domestic sewage in high-speed railway stations,the use of a self-developed composite catalytic biological carrier,starting from the coupling process,is suitable for high-speed railways.Firstly,a small laboratory test was conducted to build a reactor to realize the coupling of a composite catalytic carrier and a bio-film,and to explore the influence of nitrogen and phosphorus removal under different operating conditions(HRT,gas supply,and low temperature),the optimum operating process parameters of the reactor were obtained;field engineering applications were performed on this basis,and the on-site biological pre-treatment process was combined to meet Level A of GB18918-2002.Combined with experimental data and field engineering feedback,kinetic analysis and microbial population structure analysis of composite catalyst-biofilm coupled denitrification and dephosphorization process was researched,establishing a synchronous nitrogen and phosphorus removal mechanism coupled technology.Finally,the economical analysis of the cost of composite catalytic biological carriers and field engineering was carried out.Research indicates:(1)Laboratory test(Q=10.5?15.2 L · d--),HRT=6 h,reactor aeration DO=3.0±0.1 mg · L-1,wastewater T=9-28?.The efficiency of nitrogen and phosphorus removal is more than 85%and 90%respectively,and the quality of the effluent can meet the Level A of GB18918-2002.(2)The process parameters of On-site pilot test(Q=2.0 t · d-)are HRT=6h,central aeration is DO=3.0±0.1mg ·L-1,the equipment operation is stable,the NH4+-N,TN,TP,and COD of equipment effluent was continuous detected during the period.At present,the project has commissioned a third-party testing agency,and the test results can meet or even exceed the discharge standard.(3)The removal of nitrogen in sewage is the combined action of iron matrix catalytic internal electrolysis and bio-film.The removal of phosphorus is dominated by the chemical action of phosphorus in the sewage to participate in internal catalytic electrolysis of iron matrix;the denitrification and phosphorus of sewage established by the Eckenfelder model,the reaction constants k were 0.000998,0.005432 min-1,respectively,comparable to the same order of magnitude for a single reactor model with the same type of reactor removed.(4)High-throughput sequencing and fluorescence quantitative PCR were used to analyze the microbial community structure of the system.It was analyzed that the dominant bacteria in the top,middle,and bottom biological carriers were Sphaerotilus,Rhodobacter,and Maritimimonas,respectively.And no related phosphorus removal bacteria were found.The mechanism of combined denitrification and dephosphorization achieved through autotrophic denitrification and chemical phosphorus removal was farther verified.(5)The economic calculation of the costs of wastewater investment and running is 700 yuan/t,0.16 yuan/t,respectively.The direct investment cost of carrier is 50 yuan/t.The comparative analysis is better than other biological carriers,plus carbon source,chemical phosphorus and sewage extraction process,is a cost-effective and advanced process technology that can treat wastewater.Therefore,the research and development of this technology can provide new ideas and new processes for the upgrading of domestic sewage in high-speed railway stations,deep nitrogen and phosphorus removal,and can solve the long-standing unresolved problems of railroad low-C/N ratio domestic wastewater treatment.