基于能值的污水处理系统环境影响分析

Environmental impacts of sewage treatment system based on emergy analysis

污水处理厂及其"产物"(处理水和脱水污泥)的处理处置系统共同构成了污水处理综合系统,它从整体上涵盖了污水处理的全过程.污水处理综合系统在构建和运行的过程中主要包括两方面的环境影响:1)物质资源的消耗;2)排放污染物对环境的危害,而后者在既往有关的污水处理系统分析中往往被忽略.为了更全面地了解污水处理过程的环境影响状况,本文以能值分析理论为基础对污水处理综合系统进行分析,同时,结合生态足迹理论对系统的可持续性进行分析.结果表明:水体污染物的环境影响能值远大于大气污染物,且主要受氨氮排放量的影响;污水处理综合系统的能值消耗主要为废物流能值和本地可更新资源能值;"处理厂系统+填埋系统"的能值利用效率最高,"处理厂系统+中水回用系统+焚烧系统"的能值利用效率最低;"处理厂系统+中水回用系统+填埋系统"的环境可持续性最好,而"处理厂系统+焚烧系统"的可持续性最差.

＂Integrated sewage treatment system＂（ISTS） consists of sewage treatment plant system and their products（treated water and dewatered sludge） disposal facilities,which gives a holistic view of the whole sewage treatment process.During its construction and operation,ISTS has two main impacts on the environment,i.e.the consumption of resources and the damage of discharged pollutants on the environment,while the latter was usually ignored by the previous researchers when they assessed the impacts of wastewater treatment system.In order to more comprehensively understanding the impacts of sewage treatment on the environment,an analysis was made on the ISTS based on the theories of emergy analysis,and,in combining with ecological footprint theory,the sustainability of the ISTS was also analyzed.The results showed that the emergy of the impacts of water pollutants on the environment was far larger than that of the impacts of air pollutants,and NH3-N was the main responsible cause.The emergy consumption of ISTS mainly came from the emergy of wastewater and of local renewable resources.The ＂sewage treatment plant system ＋ landfill system＂ had the highest emergy utilization efficiency,while the ＂sewage treatment plant system ＋ reclaimed water reuse system ＋ incineration system＂ had the lowest one.From the aspect of environmental sustainability,the ＂sewage treatment plant system ＋ reclaimed water reuse system ＋ landfill system＂ was the best ISTS,while the ＂sewage treatment plant system ＋ incineration system＂ was the worst one.