Treatment of domestic wastewater under low temperature by hybrid vertical subsurface flow constructed wetland

This study evaluates the treatment effectiveness of hybrid vertical subsurface flow constructed wetland to the domestic wastewater under low temperature in northern country of China.In order to get effecitive methods for operations and managements,the removal rates of COD,NH3-N,TN,and TP are analysed in terms of hydraulic retain time(HRT)and hydraulicload rate(HLR).When the HRT at about 72~96 h,all the four indexs have good removal rates with 37.6% of NH3-N and 35.3% of TN.At the same time,they also can get effective removal ratio with 79.5% of COD and 66.7% of TP while the HLR at 1.0 m3/(m2·d).It can be found that addiational wastewater reflux is helpful for the removal of organic matters,ammonia nitrogen and total nitrogen.The optimum reflux ratio is 1.In the meantime,the results that the wetland withsand temperature's change are also indicated by the analysis of effects of temperature reducement to removal rates.