Int. J. Environ. Res. Public Health 2010, 7(9), 3422-3441; doi:10.3390/ijerph7093422
Article

Evaluation of the Removal of Indicator Bacteria from Domestic Sludge Processed by Autothermal Thermophilic Aerobic Digestion (ATAD)

1 Department of Chemical and Environmental Sciences and Material and Surface Science Institute, University of Limerick, National Technological Park, Castletroy, Limerick, Ireland 2 Sligo Institute of Technology, Cente for Sustainability, Sligo, Ireland
* Author to whom correspondence should be addressed.
Received: 17 July 2010; in revised form: 27 August 2010 / Accepted: 31 August 2010 / Published: 2 September 2010
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Abstract: The degradation of sludge solids in an insulated reactor during Autothermal Thermophilic Aerobic Digestion (ATAD) processing results in auto-heating, thermal treatment and total solids reduction, however, the ability to eliminate pathogenic organisms has not been analysed under large scale process conditions. We evaluated the ATAD process over a period of one year in a two stage, full scale Irish ATAD plant established in Killarney and treating mixed primary and secondary sludge, by examining the sludge microbiologically at various stages during and following ATAD processing to determine its ability to eliminate indicator organisms. Salmonella spp. (pathogen) and fecal-coliform (indicator) densities were well below the limits used to validate class A biosolids in the final product. Enteric pathogens present at inlet were deactivated during the ATAD process and were not detected in the final product using both traditional microbial culture and molecular phylogenetic techniques. A high DNase activity was detected in the bulk sludge during the thermophilic digestion stage which may be responsible for the rapid turn over of DNA from lysed cells and the removal of mobile DNA. These results offer assurance for the safe use of ATAD sludge as a soil supplement following processing.
Keywords: domestic sludge; safety; pathogen detection and inactivation; ATAD treatment efficiency; mobile element inactivation; SXT/R391; DNases

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MDPI and ACS Style

Piterina, A.V.; Bartlett, J.; Pembroke, T.J. Evaluation of the Removal of Indicator Bacteria from Domestic Sludge Processed by Autothermal Thermophilic Aerobic Digestion (ATAD). Int. J. Environ. Res. Public Health 2010, 7, 3422-3441.

AMA Style

Piterina AV, Bartlett J, Pembroke TJ. Evaluation of the Removal of Indicator Bacteria from Domestic Sludge Processed by Autothermal Thermophilic Aerobic Digestion (ATAD). International Journal of Environmental Research and Public Health. 2010; 7(9):3422-3441.

Chicago/Turabian Style

Piterina, Anna V.; Bartlett, John; Pembroke, Tony J. 2010. "Evaluation of the Removal of Indicator Bacteria from Domestic Sludge Processed by Autothermal Thermophilic Aerobic Digestion (ATAD)." Int. J. Environ. Res. Public Health 7, no. 9: 3422-3441.

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