Changes in biological parameters during co-composting of sewage sludge and coal ash residues

M. Fang, Jonathan W C WONG*, G. X. Li, Ming Hung WONG

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

51 Citations (Scopus)


Coal ash residues, including fly ash (FA) and lagoon ash (LA), were co-composted with dewatered sludge for 100 days in a bench-scale composting system and biological parameters were monitored to evaluate the effect of ash residues on the composting process. Coal ash residue amendment caused a rise in alkalinity and salinity, but had no adverse effect on the population of thermophilic bacteria except for 25% FA amendment. All enzyme activities decreased with composting time. β-glucosidase and alkaline phosphatase activities were reduced with an increase in ash residue amendment, while no significant reduction was noted for urease and dehydrogenase activities after 20 days of incubation. Positive correlations were obtained among B-glucosidase, alkaline phosphatase and urease activities, while no correlation was found between thermophilic bacteria and enzyme activities. With the exception of 25% FA-amended sludge compost, addition of coal ash residues in sewage sludge is feasible and showed little effects on metabolic activity during composting process.

Original languageEnglish
Pages (from-to)55-61
Number of pages7
JournalBioresource Technology
Issue number1
Publication statusPublished - Apr 1998

Scopus Subject Areas

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal

User-Defined Keywords

  • β-glucosidase
  • Alkaline phosphatase
  • Coal fly ash
  • Composting
  • Dehydrogenase
  • Lagoon ash
  • Sewage sludge
  • Thermophilic bacteria
  • Urease


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