Phosphorus was recovered from the ash obtained after combustion at different temperatures (600 °C, 750 °C, 900 °C) and gasification (obtained at 820 °C using a mixture of air and steam as fluidizing agent) of char from sewage sludge fast pyrolysis carried out at 530 ºC. Depending on the extraction conditions (type of acid, extraction time and acid concentration) phosphorus yields of 90% to 100% are reached. Char ash seems to be a renewable resource of phosphorus. It could be an alternative to rock phosphate for fertilizers production. The combination of these processes contributes to the integral exploitation of sewage sludge.

Proceedings of the 21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark, pp. 500-505