Demonstrative Study on Treatment of Domestic Sewage by Horizontal Subsurface-flow Constructed Wetland

A wastewater treatment system with horizontal subsurface-flow constructed wetland as the main process was used to treat the domestic sewage which was characterized by small quantity and variable sewage quality,at one resident site of the Tuha Oilfield,where the usable land is ample.The results show the constructed wetland system can satisfy the treatment requirement of the domestic sewage in northwest oilfield,and the average removal efficiencies of SS,COD,BOD5 and NH3-N are about 95%,75%,75% and 95% respectively. The average concentration of BOD5 in the effluent is less than 10 mg/L,and the effluent quality can meet the requirement for landscaping water.Through the reasonable design,the effluent and the sludge from the treatment system are both reused for landscaping,achieving zero pollution discharge.The treatment system has low operation cost and easy management.The demonstrative wastewater treatment system embodies the sustainable design concept.