Research on nitrogen removal of secondary effluent of wastewater treatment plant in horizontal subsurface-flow constructed wetlands

By investigating the nitrogen concentrations in effluents of the horizontal subsurface-flow constructed wetlands under the conditions of different kinds of substrates, residence time and heights, as well as the nitrogen concentrations changes along the flow in the wetlands, the nitrogen removal routes in the wetlands were analyzed. The results demonstrated that the wetland system with zeolites demonstrated greater efficiency in the removal of nitrogen. There was a higher nitrogen removal rates at the bottom of the wetland system owing to an aerobic-anoxic environment. In that a more efficient reoxygenation was attained at the front of the system, it achieved a higher nitrogen removal rates.