Novel recycling of phosphorus-recovered incinerated sewage sludge ash residues by co-pyrolysis with lignin for reductive/sorptive removal of hexavalent chromium from aqueous solutions

Qiming Wang, Jiang shan Li, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

5 Citations (Scopus)


Incinerated sewage sludge ash (ISSA), a by-product generated from the combustion of dewatered sewage sludge, has been extensively studied as a secondary resource for phosphorus recovery by acid extraction methods. Recycling of the P-recovered ISSA residues is crucial to complete and sustain the whole process. In this study, the ISSA residue rich in iron was reused and co-pyrolyzed with lignin at 650, 850 and 1050 °C under N2 atmosphere for the synthesis of a composite material to remove hexavalent chromium (Cr(VI)) from aqueous solutions. Characterization analysis including XRD, XPS, and FTIR showed that iron oxides in the residue were reduced to zero valent iron at 1050 °C that exhibits the optimal Cr(VI) removal performance. The Cr(VI) removal process was rapid and reached a plateau at around 30 min. The maximum removal rate was obtained at pH 2.0, which was conducive for the treatment of a synthetic Cr(VI)-containing wastewater in fix-bed column experiments, whereby Cr(VI) as well as total Cr were continuously removed. Overall, this study proposed a new routine for the recycling of ISSA residue after phosphorus recovery by the acid extraction method and provided a value-added product for Cr(VI) removal from wastewaters.

Original languageEnglish
Article number131434
Publication statusPublished - Dec 2021


  • Chromate removal
  • Incinerated sewage sludge ash
  • Lignin
  • Pyrolysis
  • Zero valent iron

ASJC Scopus subject areas

  • Environmental Engineering
  • Chemistry(all)
  • Environmental Chemistry
  • Pollution
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis

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