In Response: What are the challenges and prospects? An academic perspective

摘要

Effluents of municipal wastewater treatment plants (WWTPs) represent complex mixtures of compounds. Ingredients include, for example, suspended solids, nutrients, urban runoff, miscellaneous chemicals of various origins, and a large diversity of microbes and pathogens. Chemical analyses reveal that even the most advanced treatment technologies fail to completely remove or degrade all compounds of ecological concern. Consequently, WWTP effluents discharged into receiving water bodies still provide the basis for declines in chemical and ecological surface water quality. In Europe alone, the per capita emission of domestic sewage is assumed to be 200 L/d, culminating in several trillion liters (10~(18)) of treated effluents disposed of in surface waters. During the past decade, wastewater treatment across Europe and in other developed regions of the world remarkably improved. Meanwhile, the connection rate to wastewater treatment is about 80% to 90% in most of Europe; however, the percentage of the population not connected to treatment systems is especially high in southeastern Europe (30-60%). In these regions, tertiary treatment is the exception rather than the rule (9% compared with 50-70% in the rest of Europe). Facts and figures clearly demonstrate that the release of municipal wastewater effluents into the water cycle is of concern because of limited dilution factors, problematic chemical composition, and effects observed in aquatic wildlife.