Sewage sludge as a fertilizer and soil conditioner
The Norwegian Scientific Committee for Food and Environment (VKM) will assess whether the use of sewage sludge as a fertilizer and soil conditioner may have negative effects on health and the environment in Norway.
The assessment is commissioned by the Norwegian Food Safety Authority, which needs more knowledge about sewage sludge as a fertilizer and soil conditioner to ensure both its safe use and the preservation of agricultural soil.
The assignment has three main questions.
First, VKM will identify substances in sewage sludge that may pose a risk to health and the environment. This identification will be based on the Norwegian Environment Agency's list of relevant substances hazardous to health and the environment, used by the Norwegian Environment Agency and the Norwegian Water organisation to evaluate sewage sludge conducted every five years.
VKM will also evaluate whether there are substances not found on this list which may still pose a risk, due to them having a high potential for causing negative effects in the food chain.
Based on this, VKM will assess and prioritize which substances should be included in a risk assessment.
VKM will evaluate the risk associated with current practices for sewage sludge use and new methods for using sewage sludge as a fertilizer and soil conditioner. EU regulations on use of sewage sludge are less restrictive than in Norway. The Norwegian Food Safety Authority is requesting VKM to assess the risk to the environment and humans, were grazing and harvesting of feed to occur three weeks after sewage sludge is spread on meadows and pastures, and for the harvesting of vegetables, fruits, and berries that have received sewage sludge 10 months before harvesting.
VKM will evaluate whether the methods of application and the quantity of sewage sludge or products based on sewage sludge, affect the risk. In addition, VKM will evaluate whether thermal hydrolysis, a method for sanitizing the sludge, can affect the breakdown of hazardous substances.
The use of sewage sludge as a fertilizer and soil conditioner is more widespread in Norway than in many other countries. Norwegian wastewater treatment methods differ slightly from those common in Europe, and this can affect the content of organic contaminants, Norwegian soil and climate conditions may also play a role, particularly in the degradation and binding of these substances.
In Norway, between 50 and 60 percent of sewage sludge is applied to agricultural land, but there are significant regional variations. In 2018, in Østfold, Oslo/Akershus, and Vestfold, more than 95 percent of sewage sludge was applied to agricultural land, while the proportion was very low in areas with grass production.
The VKM project team consists of:
• Trine Eggen, Panel on Animal Feed (Scientific Leader)
• Aksel Bernhoft, Panel on Animal Feed
• Gunnar Eriksen, external expert, Norwegian Veterinary Institute
• Belinda Flem, Panel on Animal Feed
• Christiane Fæste, Panel on Animal Feed
• Merete Grung, external expert, Norwegian Institute for Water Research
• Veronika Sele, Panel on Animal Feed
• Håvard Steinshamn, Panel on Animal Feed
• Stefan Trapp, external expert, Technical University of Denmark
• Christian Vogelsang, Panel on Plant Protection
• Nana Yaa Boahene, VKM Secretariat
• Tron Gifstad, VKM Secretariat (Project Manager)
The risk assessment is to be approved by the Panel on Animal Feed and is planned for publication on December 15, 2025.