Influence of different mixing ratios on in-vessel co-composting of sewage sludge with horse stable straw bedding waste: Maturity and process evaluation

Jonathan W C WONG*, Ammaiyappan Selvam, Zhenyong Zhao, S. M. Yu, Alex C.W. Law, Patricia C.P. Chung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Composting sewage sludge alone would reduce the decomposition efficiency due to free limited porosity in sludge. To alleviate this, the use of horse stable straw bedding waste (HSB) was evaluated as a co-composting material with sewage sludge in a 10 tonnes day -1 in-vessel composter for a period of 7 days before curing in a static aeration pile. Sludge was mixed with HSB at 1: 1.5 (HSL) and 1: 2.9 (LSL) on a fresh weight basis. After a composting period of 56 days, both mixing ratios demonstrated to be feasible with LSL having a better organic decomposition and a shorter time to reach maturity. The overall decomposition rates were 52.0 and 58.9% (dry weight basis) for HSL and LSL, respectively. In both treatments, temperature in the in-vessel composters could reach 65°C, which was sufficient to remove the pathogens. Although both products were free of pathogens, HSL exhibited a higher ammoniacal nitrogen contents but a lower seed germination index than that of LSL indicating a higher phytotoxicity and a longer curing period would be required. It can be concluded that HSB provided a better composting conditions at a mixing ratio of 1: 2.9

Original languageEnglish
Pages (from-to)1164-1170
Number of pages7
JournalWaste Management and Research
Volume29
Issue number11
DOIs
Publication statusPublished - Nov 2011

Scopus Subject Areas

  • Environmental Engineering
  • Pollution

User-Defined Keywords

  • Co-composting
  • horse bedding waste
  • in-vessel
  • maturity
  • sewage sludge

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