A Study On Construction And Application Of Environmental Benefit Performance Evaluation System Of Constructed Wetland

Constructed wetland(CW)has the advantages of simple process,low operating cost,good purification effect,and diverse ecological environments.It has been currently widely used in the deep treatment of wastewater tailwater and water ecology management in watersheds.At present,the research on CWs mainly focuses on process optimization and pollution removal mechanism to improve the pollutant purification effect,but there is a lack of performance evaluation research on the environmental benefits of CWs.By evaluating the performance of CWs management will help to optimize the design and operating parameters of CWs,and improve the management level of CWs.Especially in the context of "carbon peaking and carbon neutrality",standardizing the pollution reduction and carbon reduction work of CWs has important scientific significance and practical value for promoting the healthy development of CWs.In this study,based on the hierarchical analysis method and fuzzy integrated assessment model,the performance evaluation system of the environmental benefits of large-scale CWs is constructed by using literature,field research,questionnaires and expert argumentation.Taking typical CWs projects in Shandong Province as the study object,an empirical study was carried out to systematically analyze the status quo and existing problems of CW projects;In addition,a large-scale CW carbon footprint(CF)accounting method was constructed to discuss typical projects under different pollution loads based on the life cycle theory.The CF differences of large-scale CWs are compared and analyzed with other tail water advanced treatment technologies.The main conclusions obtained are as follows:1.Firstly,starting from the function of CW,a hierarchical index system of environmental benefit performance of CW is established,including secondary indexes of project cost,water purification,operation and management,ecological benefit,economic benefit and social benefit of CW.Meanwhile,the standard values of 24 evaluation indicators were determined by comprehensively using various means such as literature,field investigation,questionnaire survey and expert argumentation.The ladder hierarchical structure model was constructed,the weight questionnaire was compiled by Yaahp 12.9 software,the expert weight was determined by SPSS 29.0 software cluster analysis,and the weight coefficient of each index in the CW environmental benefit performance evaluation index system was calculated by combining the group analytic hierarchy process.Finally,the evaluation indicators are divided into 5 levels:excellent,good,medium,poor,and poor,and the criteria for giving the evaluation of indicators are described.2.This article selected four typical large-scale CWs in Shandong Province to field research and applied the constructed comprehensive evaluation model for environmental benefits performance of CWs to evaluate their environmental benefits performance.The results showed that Tai’an CW-D has the largest proportion of"excellent" environmental benefit performance,and its environmental benefit performance comprehensive evaluation index score is 3.9287.Based on the secondlevel indicators,a comprehensive analysis of the evaluation indicators was carried out.Based on the index analysis results,specific optimization strategies were proposed for six aspects of project cost,water purification,operation management,ecological benefits,economic benefits and social benefits.3.On the basis of on-site sampling and research on the case of CW,based on the life cycle theory,and with large-scale research on the case of CWs as the research object,the CF accounting method system of large-scale research on the case of CWs was optimized.A CF model was established for two types of with different pollution loads,and the differences in CFs of different CWs were further compared and analyzed;The CF difference analysis between research on the case of CWs and other advanced treatment technologies was carried out.The results show that the low pollution load of research on the case of CWs can help reduce life-cycle greenhouse gas emissions.At the same time,comparing with membrane treatment and biofilter tail water advanced treatment technology,CWs have huge low-carbon and economic advantages in terms of energy consumption,economic cost and environmental benefits.