河口岛屿农村地区原位与分散生活污水处理模式的环境与经济对比分析

农村污水排放所导致的环境问题日益突出，各地均大力推动污水处理模式的建立与优化.但农村污水处理模式综合效能评价体系匮乏，且多以处理工艺为主，少量考虑了管网收集系统的环境经济影响.另外，河口岛屿因其独特的自然区位，生态更加脆弱敏感，研究其污水处理问题更具有价值与意义.因此，本研究选取河口岛屿为研究对象，以崇明为例，运用生命周期评价和经济性分析理论，对比分析了分散与原位两种生活污水处理模式，包含收集和处理系统两个子系统，以及建设和运行两个阶段的环境影响与经济性.结果表明：原位和分散模式环境影响总值分别为1.75×10^-11和0.66，分散模式更具环境优势；户均成本分别为1.80万元和1.66万元，相比原位模式而言，在相同去除效果条件下，分散模式处理更有利于节约单位投资费用；处理系统为污水处理模式主要环境影响贡献子系统，其运行阶段为主要贡献阶段，且收集系统更有环境无害化和经济优势；海洋生态毒性潜值和人体毒性潜值为主要环境影响类型.

Environmental and economic comparative analysis of in-situ and decentralized domestic sewage treatment modes in rural areas of Hekou Island

The environmental problems caused by rural sewage discharge have become increasingly severe. In response, the affected localities have vigorously pursued to establish and optimize sewage treatment models. However, a systematic approach to evaluate the performance of rural sewage treatment is lacking, and limited attention has been paid to the environmental and economic impacts of the pipe network collection system, as most of the existing evaluations have rather focused on treatment processes. For estuary islands, their unique natural locations and the associated fragile and sensitive ecological environment, can further complicate the water pollution problems and thus make evaluating the performance of sewage discharge treatment even more interesting and of greater value. Therefore, this study intends to focus on estuary islands, and takes Chongming as a case study. Using life cycle assessment and economic analysis, a comparative study of two processing modes, decentralized and in-situ, both of which consist of the collection and the processing subsystems, is carried out. The environmental impacts and the economic aspects are also compared for the construction and the operation phase, respectively. The results show that the total environmental impact values of in-situ and decentralized modes are 1.75×10^-11 and 0.66, respectively, with the decentralized modes having greater environmental advantages; the average household cost is RMB 18800 yuan and 16600 yuan, respectively. Compared with the in-situ model, to achieve the same level of removal effects, the distributed mode treatment is more competitive in terms of saving the per unit investment cost. The treatment subsystem is the main contributor to the environmental impacts associated with the sewage treatment model, and the operation phase is the major player. Meanwhile, the collection phase is relatively advantaged in being environmentally harmless and economically viable. And, the marine ecological toxicity potential and human toxicity potential are the main types of environmental impacts.