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Effect of Different Temperature on Sewage Treatment of Constructed Wetlands Pretreatment System

In order to further investigate the effect of temperature on the performance of the pretreatment system of constructed wetlands, two pilot-scale units with dimensions of 2m in length and 1m in width were operated to treat decentralized sewage focusing on the removal efficiency of floated-bed bio-film (FBF) pretreatment system treating influent under different temperature continuously from April 2011 to March 2012 in parallel experiments in Chengdu, Sichuan Province. The results showed that the average removal efficiency of TP, TN, NH3-N and COD were (22.1%, 31.8%, 29.4% and 59.8%), (34.7%, 31.2%, 22.5% and 34.1%) and (53.1%, 56.8%, 53.6% and 41.8%) at different temperature of 10°C, 10°C to 20°C and exceeded 20°C respectively. The effluent concentrations of NH3-N reached Class II demand of GB 18918-2002 in different temperature. TN reached Class I-B demand when the water temperature was above 20°C. TP reached Class II and Class III demand when the water temperature was above 10°C and below 10°C, respectively. The TN, NH3-N and TP removal efficiencies showed to great influence on temperature, however COD on the contrary. Pretreatment system alleviated the hidden clogging troubles of the subsequent potential filter pools in wetland system to the maximum and ensured the continuous high-load treating ability of the wetland system. The pretreatment technology of the floated-bed bio-film system is a small, flexible and economical device which is worthy of promotion.