Chemical state of chromium in sewage sludge ash based phosphorus-fertilisers

Christian Vogel; Christian Adam; Peter Kappen; Tara Schiller; Ewelina Lipiec; Don McNaughton

doi:10.1016/j.chemosphere.2013.12.012

Chemical state of chromium in sewage sludge ash based phosphorus-fertilisers

Chemosphere. 2014 May:103:250-5. doi: 10.1016/j.chemosphere.2013.12.012. Epub 2013 Dec 24.

Authors

Christian Vogel¹, Christian Adam², Peter Kappen³, Tara Schiller⁴, Ewelina Lipiec⁵, Don McNaughton⁶

Affiliations

¹ School of Chemistry, Monash University, Wellington Road, Clayton 3800, Victoria, Australia; BAM Federal Institute for Materials Research and Testing, Division 4.4 Thermochemical Residues Treatment and Resource Recovery, Unter den Eichen 87, D-12205 Berlin, Germany. Electronic address: [email protected].
² BAM Federal Institute for Materials Research and Testing, Division 4.4 Thermochemical Residues Treatment and Resource Recovery, Unter den Eichen 87, D-12205 Berlin, Germany.
³ Australian Synchrotron, 800 Blackburn Road, Clayton 3168, Victoria, Australia; Department of Physics, La Trobe University, Bundoora 3086, Victoria, Australia.
⁴ School of Chemistry, Monash University, Wellington Road, Clayton 3800, Victoria, Australia; Department of Materials Engineering, Monash University, Wellington Road, Clayton 3800, Victoria, Australia.
⁵ School of Chemistry, Monash University, Wellington Road, Clayton 3800, Victoria, Australia; The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, E. Radzikowskiego 152, 31-342 Kraków, Poland.
⁶ School of Chemistry, Monash University, Wellington Road, Clayton 3800, Victoria, Australia.

PMID: 24373226
DOI: 10.1016/j.chemosphere.2013.12.012

Abstract

Sewage sludge ash (SSA) based P-fertilisers were produced by thermochemical treatment of SSA with Cl-donors at approximately 1000°C. During this thermochemical process heavy metals are separated as heavy metal chlorides via the gas phase. Chromium cannot be separated under normal conditions. The risk of the development of toxic Cr(VI) during the thermochemical process was investigated. X-ray Absorption Spectroscopy measurements showed that SSA and thermochemically treated SSA with CaCl2, MgCl2 and NaCl contain Cr(III) compounds only. In contrast, treating SSA with elevated quantities of Na2CO3, to enhance the plant-availability of the phosphate phases of the fertiliser, developed approximately 10-15% Cr(VI). Furthermore, Raman microspectroscopy showed that using Mg-carbonate reduces the risk of a Cr(VI) development during thermochemical treatment. Additionally, leaching tests showed that only a Cr-water solubility>10% is an indicator for Cr(VI) in SSA based P-fertilisers.

Keywords: Chromium; Fertiliser; Raman microspectroscopy; Sewage sludge ash; X-ray Absorption Spectroscopy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Chromium / chemistry*
Fertilizers*
Phosphorus / chemistry*
Sewage / chemistry*
Solubility
Spectrum Analysis, Raman
X-Ray Absorption Spectroscopy

Substances

Fertilizers
Sewage
Chromium
Phosphorus