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4.3        Zero pollution and waste water treatment

Health protection and prevention of pollution continue to be the key purpose of sewage and urban waste water treatment. Improved scientific knowledge since the 1990s has shown the presence of many pollutants in surface waters, and many of these arise from chemicals and products that we use in our homes and workplaces. Cleaning, washing and runoff introduce these into the waste water stream. Such societal and sectoral issues are beyond the capacity of water managers to resolve, but rather, require wholesale review of what substances we choose or allow to be used. Such is the role for the Chemicals for Sustainability Strategy, launched by the EC in 2020 (EC, 2020). Among its ambitions, the Strategy aims to ban the most harmful chemicals in consumer products and allow use of such substances only where essential. This is key to reducing the load of harmful chemicals into waste water. The ambition to boost the production and use of chemicals that are safe and sustainable by design should lead to lower chemical pollution over the longer term. In turn, lowered pollution loads in waste water will reduce the need for intensive treatment i.e. turning from a vicious into a virtuous circle.

Meanwhile, UWWTPs face the challenge of cleaning up waste water to meet more demanding standards set in legislation. Modelling for the revised UWWTD by the JRC has examined the costs and benefits of micropollutant removal, considering ca. 1200 chemicals assumed as a proxy of the total pollution conveyed by raw wastewater. This has shown that advanced treatment for micropollutants at all plants in Europe  with a capacity of 100 000 p.e. or more could reduce the overall toxicity of discharged effluents by about 40% (JRC, 202x).

The decisions taken to addressing sewage treatment through any particular approach are necessarily local. Water managers aim to optimise according to local requirements and possibilities: ensuring and enabling circularity principles form part of those considerations is the role of policymakers. Where trade-offs come into play, ensuring the protection of human health and the environment should take primacy.