Design analysis of constructed wetlands for treatment of terminal effluent of wastewater treatment plants from technical standard perspective

The constructed wetlands (CWs) technology has been gradually applied to the upgrading and reconstruction of wastewater treatment plants (WWTPs) and the utilization of terminal effluent of WWTPs in China, and has become an important technical research field. Some national and local responsible departments and professional associations have promulgated and implemented several technical standards, which are used to guide and standardize the design and construction of CWs for treatment of terminal effluent of WWTPs. The application status of CWs projects for treatment of terminal effluent of WWTPs at home and abroad and the implementation of relevant technical standards guiding the design and construction of CWs were summarized, and the process selection and structure design parameters in the technical standards of CWs at different levels were compared and analyzed. By comparing the feasibility and economy of the carbon level control strategies of CWs and the accessibility of the actual project applications, it was found that the wetland structure optimization, process improvement and coupling process were the better strategies and pathways to optimize the design of CWs projects and enhance their nitrogen removal efficiency. Meanwhile, in order to ensure the safety and normal operation of CWs projects, it was suggested that the total water balance of wetlands should be calculated under the local hydrological conditions during the design of CWs projects. It was necessary to build a basic database based on substrates and aquatic plant selection, engineering operation monitoring and other aspects to strengthen the guiding role of technical standards in the whole life cycle of CWs.