Effect of Hydraulic Loading on Removal Efficiency of the Folds Stable Surface Flow Wetland

Three folds stable surface flow wetlands (FSSFWs) were operated at different hydraulic loadings of 0.80, 0.53 and 0.27m(3)/ (m(2).d) to treat the decentralized domestic sewage. And we investigated the effect of the hydraulic loading rate (HLR) on the removal efficiency of FSSFWs by measuring five indicators of chemical oxygen demand (COD), total nitrogen (TN), ammonium (NH3-N), total phosphorus (TP) and suspended substance (SS). The research results indicated that the hydraulic loading had great impact on the removal efficiency of FSSFWs, and was looked upon as one crucial factor for FSSFWs design. The removal efficiency of FSSFWs presented a downward trend in various degrees along with the increase of hydraulic loading. Also the hydraulic loading had greater influences on the removal rate of NH3-N and TN than COD, TP and SS. Considering the operation costs, the treatment capacity and the purification effect in this experiment, we could ensure the efficient and stable operation of FSSFWs with HLR at 0.53 m(3)/ (m(2).d) and HRT at 0.4 m(3).d(-1), which were the most appropriate options.