1. Council directive 91/271/EEC of 21 May 1991 concerning urban waste-water treatment;Off. J. Eur. Communities,1991
2. European Commission (2023). COMMISSION STAFF WORKING DOCUMENT EVALUATION - Council Directive 86/278/EEC of 12 June 1986 on the protection of the environment, and in particular of the soil, when sewage sludge is used in agriculture. SWD(2023) 157 final. Brussels (Belgium), 22 May 2023. Available online: https://ec.europa.eu/transparency/documents-register/detail?ref=SWD(2023)157&lang=en (accessed on 22 August 2023).
3. Mass and energy balances of sludge processing in reference and up-graded wastewater treatment plants;Mininni;Environ. Sci. Pollut. Res.,2015
4. B. Vallet (2018). Sewage sludge destination in Europe. Presentation at the European Sustainable Phosphorus Platform (ESPP) General Assembly, Brussels (Belgium), 4 December 2018. Available online: http://www.eureau.org/resources/past-events/water-events-docs/3430-sewage-sludge-destination-in-europe/file (accessed on 12 January 2023).
5. The European Critical Raw Materials review,2014