Incineration of Sludge combined with phosphorus recycling
The aim of this project is to develop a basis that highlights the pros and cons of sludge incineration, considered from a holistic perspective and based on full-scale and pilot-scale experiments.
From a resource perspective, it is desirable to recirculate the nutrients present in sludge, such as phosphorus, nitrogen and organic material, to agricultural land. This, however, requires that the sludge must meet high standards of purity as the sludge could also contain some pollutants. In 2019, the Swedish government did a special investigation on how requirements for the extraction of phosphorus from sewage sludge and a ban on spreading sewage sludge should be designed. The final report, published in January 2020, suggested a requirement of recycling at least 60% of the phosphorus contained in the sewage sludge for public wastewater treatment plants exceeding 20,000 pe.
Incineration of sludge provides the possibility of destroying pollutants present in the sludge, such as pharmaceutical residues and microplastics, while also creating an opportunity to recycle nutrients, such as phosphorus, from the ashes. This project investigates opportunities for mono-incineration of sludge, and co-incineration with recycled wood chips. Life cycle analysis is used to evaluate the potential environmental impact of sludge treatment if the treatment method is changed from composting to incineration (including phosphorus recovery from ashes). IVL is the project manager and carries out all evaluations and analyses in collaboration with other partners.