Phosphorus recovery from sewage sludge: Two-step leaching process with acid and base
2007 (English)In: Integration and optimisation of urban sanitation systems: Proceedings of Polish-Swedish seminars / [ed] E. Plaza, E. Levlin, 2007, 71-80 p.Conference paper (Other academic)
In earlier studies sludge incineration ash and SCWO-residues have been leached with acid andbase. Acid leaching gives a high degree of recovery but releases besides phosphate also the mainpart of other metals (including heavy metals). Leaching with base (NaOH) gives a less dissolutionof metals however with lower degree of recovery (up to about 50 %). When leaching with base,the calcium content in the sludge probably binds phosphorus as calcium phosphate.In this study a two-step leaching process has been tested. Ash and SCWO-residues are in the firststep leached with acid, with the main purpose to dissolve calcium. After leaching experiments withhydrochloric acid and acetic acid at different pH-levels from 3 to 6 leaching with acetic acid at pHlevel4 was chosen as the first leaching step. With a weak acid the dissolution reaction can occur atthe desired pH-level without limitation caused by insufficient amount of acid. In the secondleaching step the solid products was leached with 1 M sodium hydroxide. Two-step leaching gavefor SCWO-residue 23% higher leaching of phosphate and for sludge incineration ash 11 % higherleaching. However, aluminium was also dissolved in the second leaching step, and has to beseparated from the phosphate in a third process step.
Place, publisher, year, edition, pages
2007. 71-80 p.
, Joint Polish - Swedish reports, ISSN 1650-8610 ; 13
Acid, Base, Leaching, Phosphorus recovery, Sewage sludge
IdentifiersURN: urn:nbn:se:kth:diva-86469ISBN: 978-91-7178-826-9OAI: oai:DiVA.org:kth-86469DiVA: diva2:500738
Polish-Swedish seminars, Cracow, March 17-18, 2005
QC 201205222012-02-132012-02-132012-05-22Bibliographically approved