Phosphorus recovery and leaching of trace elements from incinerated sewage sludge ash (ISSA)

Le Fang, Jiang shan Li, Ming Zhi Guo, C. R. Cheeseman, Daniel C.W. Tsang, Shane Donatello, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

110 Citations (Scopus)


Chemical extraction of phosphorus (P) from incinerated sewage sludge ash (ISSA) is adversely influenced by co-dissolution of metals and metalloids. This study investigated P recovery and leaching of Zn, Cu, Pb, As and Ni from ISSA using inorganic acids (sulphuric acid and nitric acid), organic acids (oxalic acid and citric acid), and chelating agents (ethylenediaminetetraacetic acid (EDTA) and ethylene diamine tetramethylene phosphonate (EDTMP)). The aim of this study was to optimize a leaching process to recover P-leachate with high purity for P fertilizer production. The results show that both organic and inorganic acids extract P-containing phases but organic acids leach more trace elements, particularly Cu, Zn, Pb and As. Sulphuric acid was the most efficient for P recovery and achieved 94% of total extraction under the optimal conditions, which were 2-h reaction with 0.2 mol/L H 2SO 4 at a liquid-to-solid ratio of 20:1. EDTA extracted only 20% of the available P, but the leachates were contaminated with high levels of trace elements under optimum conditions (3-h reaction with EDTA at 0.02 mol/L, pH 2, and liquid-to-solid ratio of 20:1). Therefore, EDTA was considered an appropriate pre-treatment agent for reducing the total metal/metalloid content in ISSA, which produced negligible changes in the structure of ISSA and reduced contamination during subsequent P extraction using sulphuric acid.

Original languageEnglish
Pages (from-to)278-287
Number of pages10
Publication statusPublished - 1 Feb 2018


  • Chelating agents
  • Chemical extraction
  • Incineration ash
  • Metals/metalloids removal
  • Phosphorus recovery
  • Sewage sludge

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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