Behavior of inorganic elements during sludge ozonation and their effects on sludge solubilization

Pengzhe Sui, Fumitake Nishimura, Hideaki Nagare, Taira Hidaka, Yuko Nakagawa, Hiroshi Tsuno

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


The behavior of inorganic elements (including phosphorus, nitrogen, and metals) during sludge ozonation was investigated using batch tests and the effects of metals on sludge solubilization were elucidated. A decrease of ~50% in the ratio of sludge solubilization was found to relate to a high iron content 80-120mgFe/gSS than that of 4.7-7.4mgFe/gSS. During sludge ozonation, the pH decreased from 7 to 5, which resulted in the dissolution of chemically precipitated metals and phosphorus. Based on experimental results and thermodynamic calculation, phosphate precipitated by iron and aluminum was more difficult to release while that by calcium released with decrease in pH. The release of barium, manganese, and chrome did not exceed 10% and was much lower than COD solubilization; however, that of nickel, copper, and zinc was similar to COD solubilization. The ratio of nitrogen solubilization was 1.2 times higher than that of COD solubilization (R2=0.85). Of the total nitrogen solubilized, 80% was organic nitrogen. Because of their high accumulation potential and negative effect on sludge solubilization, high levels of iron and aluminum in both sewage and sludge should be considered carefully for the application of the advanced sewage treatment process with sludge ozonation and phosphorus crystallization.

Original languageEnglish
Pages (from-to)2029-2037
Number of pages9
JournalWater Research
Issue number5
Publication statusPublished - Feb 2011


  • Excess sludge reduction
  • Metals
  • Nitrogen
  • Phosphorus
  • Sludge ozonation
  • Thermodynamic calculation

ASJC Scopus subject areas

  • Ecological Modelling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution


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