Phosphorus recovery from sewage sludge: Ideas for further studies to improve leaching
2007 (English)In: Integration and optimisation of urban sanitation systems: Proceedings of Polish-Swedish seminars / [ed] E. Plaza, E. Levlin, 2007, 61-70 p.Conference paper (Other academic)
Development of methods to recover phosphorus will make handling of sewage sludge moresustainable. In earlier studies sludge incineration ash and SCWO-residues have been leached withacid and base. Acid leaching gives a high degree of recovery but releases besides phosphate alsothe main part of other metals (including heavy metals). This gives a large separation problem andgives a complicated process technology. Leaching with base (NaOH) gives a lower degree ofrecovery (up to about 50 %) however with less dissolution of metals. When leaching with base, thecalcium content in the sludge probably binds phosphorus as calcium phosphate.To improve leaching different possibilities can be studied such as use of a two-step leachingprocess. In a first step acid leaching dissolves calcium and magnesium. Treating the leachate withsulphuric acid, calcium sulphate (gypsum) is precipitated and phosphoric acid is obtained.Remaining ash or SCWO-residual product can afterwards be treated by alkaline leaching. Anotheralternative is to study leaching at anaerobic conditions. Since ferrous iron(II) phosphate is moresoluble than ferric iron(III) phosphate the phosphate is more easily dissolved and the heavy metalcontamination will be lower.
Place, publisher, year, edition, pages
2007. 61-70 p.
, Joint Polish - Swedish reports, ISSN 1650-8610 ; 12
Acid, Base, Leaching, Phosphorus recovery, Sewage sludge
IdentifiersURN: urn:nbn:se:kth:diva-87222ISBN: 978-91-7178-825-2OAI: oai:DiVA.org:kth-87222DiVA: diva2:501525
Polish-Swedish seminars, Stockholm, Sweden, June 6-8, 2004
QC 201205162012-02-142012-02-142012-05-16Bibliographically approved