Improving phosphorus availability in sewage sludge ash through a novel microwave‐based technology

Abstract This work is connected with the increasing demand for fertilizers and the associated supply risks and market volatility in the European Union (EU). It highlights the reliance on phosphorus from Moroccan phosphate rocks and the environmental issues stemming from the overuse of phosphate‐based fertilizers. The paper suggests a shift in perspective, viewing waste as a valuable resource. Specifically, it explores the potential of recycling phosphorus from sewage sludge ash, which contains a high phosphorus concentration. The focus is on comparing two methods of phosphorus extraction from sewage sludge ashes: classical wet‐chemical extraction and a new microwave‐based technology. There is an increase in phosphorus bioavailability with the microwave treatment, making it a promising approach for waste management. An initial economic evaluation suggests that the microwave method is highly competitive, especially when compared with wet‐chemical extraction technologies. The resulting material from the microwave treatment is classified as a straight solid inorganic macronutrient fertilizer according to EU regulations.