Substance flow analysis of hazardous substances in a Swedish municipal wastewater system

In a comparative substance flow analysis two wastewater management scenarios in the Swedish town of Surahammar were assessed - a Conventional Scenario vs. a Separating Scenario. The study was restricted to a selection of 16 representative hazardous substances, including metals and organic compounds. Quantitative data of the selected hazardous substances - their presence in grey- and blackwater, and their reduction rates in the wastewater treatment plant - were gathered from the literature and our own studies. The Conventional Scenario caused an overall higher flow of the selected hazardous substances to the surrounding nature. However, the difference between both scenarios regarding emissions of hazardous substances to the receiving water was small. In general, the Separating Scenario resulted in a significantly smaller flow of hazardous substances to arable land than the Conventional Scenario. A possible management approach was suggested to be used to interpret and compare different wastewater systems, and serve to find out if and how much the flow of hazardous substances can be stopped, diverged, or transformed at the source or during transport throughout the system. System design, process barriers, and organisational and behavioural barriers were suggested, but only the first two were assessed in this study.