Hazardous substances in wastewater management

Sammanfattning: The extensive use of materials and substances in society causes diffuse source emissions that lead to uncontrolled spreading of hazardous substances, largely channelled via wastewater systems, to the surrounding nature. Complex mixtures of substances appear in wastewater as a result of use, wear, and corrosion of goods (e.g. pipes, carpets, furniture) as well as the use of household chemicals from doing the laundry and dishwashing and the use of pharmaceuticals and personal care products. As a part in analysing the flows of hazardous substances in wastewater systems, domestic wastewater fractions (greywater, urine, and faeces) were chemically characterised through full-scale field samplings at the source separating domestic wastewater systems Vibyåsen and Gebers with respect to a selected number of hazardous substances. The mass flows of hazardous metals from households emerged in similar quantities in the greywater and toilet fractions. However, ratios of hazardous metals to phosphorus and nitrogen were significantly lower in the urine than in the faecal matter and greywater. The mass flows of organic hazardous substances from households were mainly searched for in the greywater, resulting in 50-60% of the 81 measured substances being found, with representatives from all of the substance groups investigated. Of the 72 measured organic hazardous substances, 36% were found in the blackwater at Vibyåsen. However, it was not possible to exactly identify their specific sources as the mass flows of organic hazardous substances derive from numerous and diffuse household sources. The input of organic hazardous substances to urine and faeces occurs mainly via the excretion of, for instance, pharmaceuticals, pesticides, and food additives. Other examples of relevant pathways are when emptying a scouring pail and throwing in cigarette butts, snuff, etc., into the blackwater via the water closet. A possible management approach was suggested to interpret and compare different wastewater systems, and to 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 wastewater system. The barriers approach was proposed as a tool on a conceptual level as an attempt to link the use of resources and the spreading of hazardous substances to their underlying causes and driving forces (i.e. consumption and lifestyle) rather than only focusing on the emissions. Organisational and behavioural barriers, system design, process barriers, and optional recipients were suggested, implying that various kinds of measures are needed in the management of hazardous substances to achieve a change in direction towards sustainability. It was concluded that the flows of hazardous substances in wastewater systems are not only a complex issue for wastewater management, but for society as a whole.