Questions on the Swiss micropollutant strategy

One of the main sources of micropollutants (approx. 40%) is the discharge from municipal wastewater treatment plants. With end-of-pipe measures, a large proportion of these micropollutants won’t enter the water body. Another 40% of the load arises from inputs via drainage from agricultural land treated with pesticides and about 20% from inputs from industry and commerce. This report of the Swiss Federal Council shows that measures against micropollutants at the source have already been partially implemented but can still be reinforced.

In the study “Cost-Benefit Analysis of the Swiss National Policy on Reducing Micropollutants from Treated Wastewater” (Logar et al. 2014), 1000 Swiss citizens were interviewed. This study showed that the Swiss willingness to pay is very high: a household is willing to pay up to CHF 100 per year to reduce the environmental risk of micropollutants.

In Switzerland and Germany, many studies have been carried out on micropollutant abatement in recent years. However, the various studies often differ with regard to the selection of substances investigated. The abatement of organic micropollutants in (nitrifying) WWTPs is strongly substance-dependent and ranges from 0 to 100%. However, if a broad spectrum of substances is measured, it shows that average abatement performance of 30–50% is generally achieved in nitrifying WWTPs (compared to about 10–25% in non-nitrifying WWTPs). With more advanced processes, total abatement increases to more than 80%, with usually over 90% of particularly critical substances removed and no longer detectable in the effluent. The extensive abatement of a broad spectrum of micropollutants (endocrine disruptors, active pharmaceutical ingredients, biocides, etc.) is not possible with the biological processes used today (Falas et al., “Tracing the Limits of Organic Micropollutant Removal in Biological Wastewater Treatment”, Water Research 95, 240–249, 2016).

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