What sewage sludge is and conflicts in Swedish circular economy policymaking

Recycling nutrients from renewable sources, like sewage sludge, has been promoted as a step towards a circular economy by decreasing extraction and dependency on inorganic fertilizers. Implementation, however, is often controversial. In 2018, a Swedish governmental inquiry was commissioned to propose a complete ban on land application of sewage sludge to reduce soil pollution and increase phosphorus recovery. In 2020, the inquiry suggested two pathways, one to ban all land application, and one where agricultural land use should continuously be allowed. This paper is based on interviews with experts tied to the inquiry where they reference to sewage sludge, related objects, and future management. The inquiry's inability to propose a coherent suggestion is analysed inspired by the concept of multiple ontology. Several ontological versions of sewage sludge emerge that unveil tensions between concepts of danger and cleanliness, pollution and naturalness, often captured in previous studies of waste. Some versions of sewage sludge conflict, which can explain the difficulty to establish an ontologically singular knowledge base for a transformation of sewage sludge from waste to resource. Though most of the experts agree that circular economy and nutrient recycling are good things, policymaking is caught in an ontological conundrum.