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KLAR: Sewage sludge inorganic recycling

The project "KLAR - Sewage Sludge Inorganic Recycling" aims to make sewage sludge usable as an urban resource and to provide nutrients such as phosphorus (P) and nitrogen (N) as well as other inorganic valuable materials. The research project aims to develop an innovative recovery concept across the process path from gasification and purification to efficiently recover secondary recyclables. The KLAR project deals with the optimization of the process and operation management of the Dual Fluidized Bed (DFB) process at a 1 MW pilot plant to optimize the inorganic outputs. Accompanying these outputs will be characterized and plant availability evaluated. Potential recycling from Vienna sewage sludge can recover up to 1,500 t/a each of nitrogen and phosphorus. If the process is applied throughout Austria, it could be possible to cover up to 50 percent of the annual phosphorus requirement for mineral fertilizers. The project thus makes a significant contribution to CO₂ savings as well as closing the loop in the city.