Biofilm decompose on the surface is the primary removal mechanism.The gravel bed subsurface constructed wetland was used to investigate the removal efficiencies of SS, NH4+-N, BOD5, and PO43-.

• 于关渡取用旧贵子坑溪溪水，为接触曝气及地下砾间处理复合式人工湿地，主要之污染去除机制为生物膜对污染质之分解。