Potential regrowth and recolonization of salmonellae and indicators in biosolids and biosolid-amended soil

Kathleen J. Zaleski, Karen L. Josephson, Charles P Gerba, Ian L Pepper

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

This study evaluated the potential for conversion of Class B to Class A biosolids with respect to salmonellae and fecal coliforms during solar drying in concrete lined drying beds. Anaerobically (8% solids) and aerobically (2% solids) digested Class B biosolids were pumped into field-scale drying beds, and microbial populations and environmental conditions were monitored. Numbers of fecal coliforms and salmonellae decreased as temperature and rate of desiccation increased. After 3 to 4 weeks, Class A requirements were achieved in both biosolids for the pathogens and the indicators. However, following rainfall events, significant increase in numbers was observed for both fecal coliforms and salmonellae. In laboratory studies, regrowth of fecal coliforms was observed in both biosolids and biosolid-amended soil, but the regrowth of salmonellae observed in the concrete-lined drying beds did not occur. These laboratory studies demonstrated that pathogens decreased in numbers when soil was amended with biosolids. Based on serotyping, the increased numbers of salmonellae seen in the concrete lined drying beds following rainfall events was most likely due to recolonization due to contamination from fecal matter introduced by animals and not from regrowth of salmonellae indigenous to biosolids. Overall, we conclude that the use of concrete-lined beds created a situation in which moisture added as rainfall accumulated in the beds, promoting the growth of fecal coliforms and salmonellae added from external sources.

Original languageEnglish (US)
Pages (from-to)3701-3708
Number of pages8
JournalApplied and Environmental Microbiology
Volume71
Issue number7
DOIs
StatePublished - Jul 2005

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biosolids
biosolid
recolonization
regrowth
Salmonella
Soil
fecal coliform
drying
soil
rain
rainfall
pathogen
Serotyping
Desiccation
solar drying
pathogens
indicator
salmonella
desiccation
environmental conditions

ASJC Scopus subject areas

  • Environmental Science(all)
  • Biotechnology
  • Microbiology

Cite this

Potential regrowth and recolonization of salmonellae and indicators in biosolids and biosolid-amended soil. / Zaleski, Kathleen J.; Josephson, Karen L.; Gerba, Charles P; Pepper, Ian L.

In: Applied and Environmental Microbiology, Vol. 71, No. 7, 07.2005, p. 3701-3708.

Research output: Contribution to journalArticle

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