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Public health implications of Sammonella regrowth in composted biosolids

Sidhu, J., Gibbs, R.A. and Ho, G.E.ORCID: 0000-0001-9190-8812 (2003) Public health implications of Sammonella regrowth in composted biosolids. In: ORBIT 2003 Organic Recovery and BIological Treatment Proceedings of the Fourth International Conference of ORBIT Association on Biological Processing of Organics: Advances for a Sustainable Society, 30 April - 2 May 2003, Perth, Western Australia

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Composting is widely used as a biosolids stabilisation process, which also results in the reduction of human pathogens to very low levels. However, bacterial pathogens such as Salmonella and E. coli can survive composting process in low numbers, under certain conditions. Potential risks to public health posed by the regrowth of surviving Salmonella in biosolids are a cause of concern. The purpose of this study was to evaluate the public health risks posed by the regrowth of Salmonella in composted biosolids. Salmonella regrowth potential tests were carried out on composted biosolids stored for 2 to 117 weeks. Maximum growth of seed Salmonella typhimurium observed in non-sterilised composted biosolids was 9.8 x 10 2 g -1. Indigenous compost microflora was found to be the single major factor responsible for inhibiting Salmonella regrowth. In the absence of competing indigenous micro flora the maximum growth of S. typhimurium was more than 6 x 10 6 g -1. Long term storage was found to result in an increased pathogen regrowth potential. An assessment of potential public health risks associated with the use of contaminated compost was carried out on the basis of data produced in this study. The probability of infection in an event of Salmonella regrowth was found to be higher than the acceptable limits for both pica children and adults. Consequently, it is suggested that monitoring for Salmonella should be carried out prior to the distribution of biosolids.

Item Type: Conference Paper
Murdoch Affiliation(s): Environmental Technology Centre
Notes: In: Pullammanappallil, P., McComb, A., Diaz, L.F. and Bidlingmaier, W. (eds), ORBIT 2003 : organic recovery and biological treatment : proceedings of the fourth International Conference of ORBIT Association on biological processing of organics : advances for a sustainable society : 30 April-2 May 2003, Perth, Australia, pp 398-403.
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