Biosolids in food production - phosphorus recycling and food safety

There is a growing awareness of the limitations in global mineral P reserves, increasing the need to create efficient P cycles in food production. Although a considerable amount of P is returned toNorwegian agriculture with biosolids, this mainly supplements P in mineral fertilizers instead of substituting it. The agricultural benefit of the biosolid-Pis low, and instead implies a potential environmental risk as it increases the P concentration in the soil. Efficient utilization of biosolid-P calls for reliable tools to quantify the availability of P to plants in an agriculturalsystem in the short and long term. As the availability of P presumably is low in typical Norwegian biosolids, the potential for improving plant availability by adjustments in specific sewage treatment process-steps will be tested. Urban sewage, the raw material for biosolids, contains compounds originating from various and complex sources, e. g. food, personal care products, cleaning, industries and road dust. Regarding food safety, the occurrence, availabilityand/or degradation of pollutants in biosolids need to be understood. The project will supplement the report from the Norwegian Scientific Committee on Food Safety on agricultural use of biosolids with more data on heavymetals and organic pollutans. The project is expected to contribute to a safe and sustainable utilization of biosolids in agriculture. The findings are expected to give practical recommendations on how to improve the substitution of mineral P with biosolid-P in food production. It is also expected that the project will clarify the need for limitations on use of biosolids onagricultural land situated near sensitive aquatic systems.