Study On Land Infiltration Technology Of Domestic Sewage In Middle And Small Railway Stations

Most of stations are far away from city in our existing and new building railway line, the domestic sewage in the middle and small stations can't access to the municipal sewage system, the sewage was free charged in the nearest area of the station, and provoke some environment pollution along the railway line. In recent years, Environment protection was enhanced in our country, the sewage treatment along the railway line was taken serious attention by the ministry of railway and other related departments. A new railway sewage treatment technology was researched and developed according the characteristics of sewage in the small railway station, the new technology has a simple technological process, the treatment efficient was very stable, operation were very easy. The new technology would be the best way to treat the domestic sewage in the railway stations.The research combined with the technological research and development program of China Railway Fifth Survey And Design Institute Group Co.,Ltd. The program is using soil aquifer treatment system treating the domestic sewage in middle and small railway stations. The research was using the domestic sewage in the small railway stations, evaluated feasibility of the cycle immobilized biological filter—the biological immobilized pulse infiltration system—immobilized biological subsurface flow soil treatment system, and found the best conditions for each treatment unites.The conclusion of the research:(1) Cycle immobilized biological filter was the pretreatment unit of the soil treatment system organically, the technology combined the pump absorbing well, used the pressure of the pump cycled the domestic sewage in the cycle immobilized biological filter; the cycle flow was 384L/h, the removal of CODCr and NH3-N reach the highest efficiency, the CODcr was 84.34% and the NH3-N is 47.15%; the influent water in the regulating pond stayed 1 hour and concentration of CODcr in the influent water was 438.06mg/L, the removal efficiency of CODCr in the cycle immobilized biological filer was 76.53%, the system had a stronger capacity of anti-shock loading.(2) Immobilized biological pulse infiltration system used the pulse water influent, the sewage in the system alternative changed in the water distribution and water drop, concentration of the oxygen in the system improved. The result is:when the surface lode was 15cm/d, the average removal efficiency of CODCr in the immobilized biological pulse infiltration system was 50.58%, NH3-N was 40.39%, TP was 42.32%.(3) Immobilized biological subsurface flow soil treatment system was the last processing unit, the influent use the vertical drop-rise-drop-rise interchange modes, the contaminant matter in the water was sufficient contact with fillers in the tank. The result is: the removal efficiency of CODCr and NH3-N in the immobilized biological subsurface flow soil treatment system was reduced when the surface load was arising. The best surface load of the system was 12cm/d, the average removal efficiency of CODCr was 46.47%, the NH3-N was 20.83%; the system adding sponge iron, it can better combine with the microorganism, had a better removal efficiency of phosphorous, the average removal efficiency of TP was 61.89%.Summary, Cycle immobilized biological filter-biological immobilized pulse filter system—immobilized biological subsurface flow treatment system was the best soil treatment process for the treatment of domestic sewage in the railway middle and small stations. Meanwhile, the soil treatment process had stable treatment efficiency, low energy consumption, small investment, the technology had a better application prospect for the treatment of the middle and small domestic sewage system.