STUDY ON TREATMENT OF RIVER WATER BY IMPROVED SUBSURFACE FLOW-VERTICAL FLOW WETLAND

The improved artificial wetland was selected to treat river water，for its C/N deficiency and low P concentration． The improved wetland contains subsurface flow and vertical flow segments． The subsurface flow segment is filled with zeolites and rotten wood，which play the role of external carbon source． The vertical flow segment is filled with cement bricks，and planted with canna on it． The result showed that the improved wetland had high efficiency on nitrogen and phosphorus removal． Nitrogen was mainly removed during the subsurface flow segment，the removal rate of ammonia and total nitrogen could exceed 90%，and the external carbon source did not affect the quality of water． While phosphorus was removed mainly in vertical flow segment． Cements bricks had better performance on the low concentration P removal，but they need to be changed frequently，with a short lifetime． Canna had little effect on nitrogen removal of wetland．