A novel evaluation index system for comprehensively analyzing the operational performance of constructed wetlands

Abstract

Constructed wetlands (CWs) offer ecological, economic, social, and other benefits during operation, but a comprehensive evaluation system to effectively evaluate their operational performance is lacking. This study established a novel constructed wetland evaluation index system (CWEIS) to evaluate the operational performance of CWs in terms of six key aspects, ranked in order of significance: purification capacity, ecological performance, investment cost, social value, economic benefit, and management performance. New evaluation indicators, such as effluent risk, carbon emission, and carbon fixation, were incorporated into CWEIS to respond to societal demands for CW functionality. The CWEIS was successfully applied to evaluate the operational performance of four field-scale CWs which have been operated continuously for over seven years revealing functional issues during their operation. The results demonstrated that although the overall performance of the CWs was at the good level, the total nitrogen concentration in their effluent exceeded the design standard. Additionally, the evaluation scores for the land area of the CWs were below the good level, and it was found that economic benefit exhibited the most significant disparity among the secondary indicators. Consequently, this study highlighted the necessity of introducing novel substrates and optimizing operational strategies for enhancing the purification capacity of CWs. Furthermore, increasing the depth of CW to reduce land use, enriching species diversity, and expanding the applications of wetland products could further improve CW's operational performance. This study presents a novel evaluation model for CWs, and its findings positively contribute to the sustainable operation of CWs.