标题：REMOVAL OF HEPTACHLOR, HEXACHLOROBENZENE AND COMMON POLLUTANTS IN CONSTRUCTED WETLANDS UNDER LOW TEMPERATURES WITH STRAW AND MEDICAL STONE AS MEDIUM
摘要：At low temperatures (<18°C), constructed wetlands (CWs) have unsatisfactory pollutant removal efficiencies. Experiments for this study were carried out in CWs to evaluate the behavior of pollutants. Besides the common pollutants COD, BOD, TN, and TP, organochlorine pesticides heptachlor and hexachlorobenzene were also tested. A series of composite effluent samples from the wetland were analyzed. As expected, with a 2.6-day hydraulic residence time, the COD and BOD removal efficiencies were higher than 80%. The maximum removal efficiencies of TP and TN were 43.42% and 70.09%, respectively. At low temperatures, 100% of heptachlor and hexachlorobenzene were removed in CW4. CW4 was constructed with light expanded clay aggregate, medical stone, and straw, with Manchurian wild rice planted on top. CW4, therefore, has a higher temperature from the insulation, double adsorption of contaminants, and increased activity of the microbial population. In the two test sites with straw, satisfactory removal rates were obtained at low temperatures, indicating that the thermal insulation effect of straw played an important role. In a low temperature environment, the sites with straw showed a statistically significant increase in pollutant removal rates, confirming that straw effectively enhances filter performance.
关键词：Medical stone;Low temperature condition;Constructed wetlands;Straw;Heptachlor and Hexachlorobenzen
