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Die-off of human pathogens in sludge amended soil
Conference paper   Open access

Die-off of human pathogens in sludge amended soil

R.A. Gibbs, C.J. Hu, G. Ho, P.A. Phillips and I. Unkovich
Australian Water & Wastewater Association
16th Federal Convention of the Australian Water & Wastewater Association (Sydney, Australia, 02/04/1995–06/04/1995)
1995
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Abstract

Anaerobically digested sludge is commonly used both in Australia and overseas as an agricultural soil amendment. Even though a number of studies have examined the die-off of faecal indicator bacteria in sludge amended soil, there is less information concerning the die-off of human pathogens. This study examined the die-off of enteroviruses, Salmonella and Giardia in sandy soil amended with sludge which had been treated by anaerobic digestion and mechanical dewatering. Enteroviruses were not detected in sludge amended soil even though they were present in sludge in low numbers. Giardia cysts were initially present but decreased in number and were not detected after 8 weeks. Salmonella decreased to non-detectable concentrations within 8 weeks but were then re-detected after 36 weeks. It appeared that Salmonella regrew as a result of an increase in soil moisture content at the beginning of winter. Faecal coliforms also appeared to regrow after a long period of non-detection. The potential regrowth of bacterial indicator organisms and human pathogens in soil amended with wastewater sludge is of concern.

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