Abstract: A full-scale wetland,80 hm² in area,was constructed and put into operation in October 1998 in Rongcheng City ,Shandong Province for treatment of wastewater.The treatment capability of the system was 2.0×10⁴ m³·d^-1.To evaluate pollutants removal efficiency,and seasonal and annual variations of the system,water samples were collected and analyzed from January 1999 to December 2004.The results show that the constructed wetland could effectively reduce concentration of suspended solids by 73.9%,BOD₅ by 72.5%,COD_Cr by 63.8%,coliform by 99.7% and fecal coliform by 99.6%.The nitrogen removal efficiency（45.1%）was relatively low,and the phosphorous removal efficiency（30.2%）the least.BOD₅,COD_Cr,NH⁺₄-N and TP removal displayed seasonal variations.NH⁺₄-N reduction varied more dramatically with the seasons in comparison with other parameters.The COD_Cr and BOD₅ and NH⁺₄-N reduction efficiency showed a rising trend from 1999 to 2004.The TP reduction efficiency remained almost unchanged in 2001 and 2002,but began to decrease in 2003.

Key words: sewage treatment, constructed wetland, removal efficiency, seasonal variation, annual variation