Studies on subsurface-flow wetland treatment system for special thick oil production wastewater from Liaohe oilfield.

：A pilot-scale plant in Liaohe oilfield has been studied using tame reed wetland as medium to treat special thick oil production wastewater for the first time. The results show that even if the ratio of BOD5/COD of the wastewater is only 0.06, the system has obvious purifing effect; and that when the system hydraulic loading is 2cm/d, the average concentrations of oil, COD, BOD5 and TN in the treated effluent are 2.26mg/L, 77.34mg/L, 3.13mg/L and 1.66mg/L with their removal rates 91.83%, 83.16%, 90.66% and 89.37%. Respectively in addition, the treatment technology is new, economic and effective with stable effluent quality and good resistance to shock-loading. The studies on growth volume, cellulose and lignin of reeds inside and outside the system and the ratio of length/width of lignin show that the special thick oil production wastewater has no obvious influence on reed quality and the reed can be reused for papermaking.