Constructed subsurface flow wetland for treating heavy oil-produced water of the Liaohe Oilfield in China

摘要

A pilot subsurface flow constructed wetland (CW) has been constructed in the Liaohe Delta, China to treat heavy oil-produced water with large amounts of dissolved recalcitrant organic compounds. Pollutant concentrations and change of wetland plants were periodically monitored. Treatment effectiveness was evaluated and indicated high mean removal efficiencies, 8% for chemical oxygen demand (COD). 89% for biochemical oxygen demand (BOD_50, 89% for mineral oil, and 81% for total Kjeldahl nitrogen (TKN) achieved in reed bed not = 2, to produce wetland effluent average concentrations with COD 77 mg l~(-1), BOD_5 3.5 mg l~(-1), TKN 2.2 mg l~(-1), and mineral oil 2.9 mg l~(-1). We observed that during the vegetation growth period there was no influence of heavy oil-produced water on the numbers of leaves of reeds in CW, whereas, the biomasses and heights of reeds showed significant loss with increasing hydraulic loading. The heavy oil-produced water had no obvious effet on the reed indices of cellulous, lignin, pentose and the length/width ratio of cellulose.