Phosphorus recovery from sorted municipal solid waste incineration ash

Artikel i vetenskaplig tidskrift, 2015

Phosphorus (P) is an essential non-renewable resource and phosphorus recovery from secondary sources has been frequently discussed. In this study, a modified acidic dissolutionprecipitation method was developed for P recovery from sorted municipal solid waste incineration (MSWI) samples of bottom ash (BA) and fly ash (FA). The initial experiments revealed that 2 h leaching in 2.5 M HCl optimized P leaching. However, large amount of toxic metals was released. Solid phase extraction (SPE) of the leachates indicated that chelating disks removed the toxic trace metals effectively, but also extracted large amounts of P. For this reason, the procedure was not included in the suggested P recovery process. The P leaching efficiencies, i.e. the ratio of P leached from the original ash, were 30-57 %. The overall P recovery efficiencies, i.e. the ratio of P recovered from the original ash, were 33-62 %. The P content in the final precipitation products varied between 1% (BA) and 2% (FA). Although in Europe the precipitation product can be applied as a fertilizer without further treatment, this is not recommended until the amount of toxic trace metals has been reduced. However, it can serve as an alternative to low grade phosphate rock.