화학공학소재연구정보센터
Biomass & Bioenergy, Vol.65, 42-50, 2014
Phosphorus recovery from sewage sludge char ash
Phosphorus was recovered from the ash obtained after combustion at different temperatures (600 degrees C, 750 degrees C and 900 degrees C) and after gasification (at 820 degrees C using a mixture of air and steam as fluidising agent) of char from sewage sludge fast pyrolysis carried out at 530 degrees C. Depending on the leaching conditions (extraction time, acid load and acid concentration, and type of acid) 90% mass of the original P was recovered. Regarding char combustion ash, higher phosphorus yields are obtained from ash obtained at 900 degrees C than at 600 degrees C and 750 degrees C when using sulphuric acid. Combustion temperature does not affect phosphorus leaching with oxalic acid. A contact time of 2 h and an oxalic acid load of 10 kg kg(-1) of P seem sufficient for phosphorus extraction. Almost all phosphorus present in gasification ash is leached after 2 h with both sulphuric and oxalic acid using an acid load of 14 kg kg(-1)of P. Char ash is a possible renewable source of phosphorus and it can be an alternative to rock phosphate in fertilizer production. The combination of sewage sludge pyrolysis, combustion or gasification of the char and phosphorus extraction from the final solid residue contributes to the integral exploitation of sewage sludge. (C) 2014 Elsevier Ltd. All rights reserved.