Previous Article | Next Article 
Applied and Environmental Microbiology, July 2009, p. 4531-4538, Vol. 75, No. 13
0099-2240/09/$08.00+0 doi:10.1128/AEM.02873-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Propagation of Human Enteropathogens in Constructed Horizontal Wetlands Used for Tertiary Wastewater Treatment 
Thaddeus K. Graczyk,1,2,3,5*
Frances E. Lucy,4,5,6
Leena Tamang,1
Yessika Mashinski,1,2
Michael A. Broaders,4,5
Michelle Connolly,4,5 and
Hui-Wen A. Cheng5,7
Department of Environmental Health Sciences, Division of Environmental Health Engineering, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, Maryland 21205,1 Johns Hopkins Center for Water and Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, 615 N. Wolfe Street, Maryland 21205,2 Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, Maryland 21205,3 Department of Environmental Science, School of Science, Institute of Technology, Sligo, Ireland,4 Centre for Biomolecular Environmental Public Health Research, School of Science, Institute of Technology, Sligo, Ireland,5 Environmental Services Ireland, Lough Allen, Carrick on Shannon, County Leitrim, Sligo, Ireland,6 Department of Research, School of Science, Institute of Technology, Sligo, Ireland7
Received 17 December 2008/ Accepted 21 April 2009
Constructed subsurface flow (SSF) and free-surface flow (FSF) wetlands are being increasingly implemented worldwide into wastewater treatments in response to the growing need for microbiologically safe reclaimed waters, which is driven by an exponential increase in the human population and limited water resources. Wastewater samples from four SSF and FSF wetlands in northwestern Ireland were tested qualitatively and quantitatively for Cryptosporidium spp., Giardia duodenalis, and human-pathogenic microsporidia, with assessment of their viability. Overall, seven species of human enteropathogens were detected in wetland influents, vegetated areas, and effluents: Cryptosporidium parvum, C. hominis, C. meleagridis, C. muris, G. duodenalis, Encephalitozoon hellem, and Enterocytozoon bieneusi. SSF wetland had the highest pathogen removal rate (i.e., Cryptosporidium, 97.4%; G. duodenalis, 95.4%); however, most of these values for FSF were in the negative area (mean, –84.0%), meaning that more pathogens were discharged by FSF wetlands than were delivered to wetlands with incoming wastewater. We demonstrate here that (i) the composition of human enteropathogens in wastewater entering and leaving SSF and FSF wetlands is highly complex and dynamic, (ii) the removal and inactivation of human-pathogenic microorganisms were significantly higher at the SSF wetland, (iii) FSF wetlands may not always provide sufficient remediation for human enteropathogens, (iv) wildlife can contribute a substantial load of human zoonotic pathogens to wetlands, (v) most of the pathogens discharged by wetlands were viable, (vi) large volumes of wetland effluents can contribute to contamination of surface waters used for recreation and drinking water abstraction and therefore represent a serious public health threat, and (vii) even with the best pathogen removal rates achieved by SSF wetland, the reduction of pathogens was not enough for a safety reuse of the reclaimed water. To our knowledge, this is the first report of C. meleagridis from Ireland.
* Corresponding author. Mailing address: Department of Environmental Health Sciences, Division of Environmental Health Engineering, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205. Phone: (410) 614-4984. Fax: (410) 955-0105. E-mail: tgraczyk{at}jhsph.edu
Published ahead of print on 1 May 2009.
Applied and Environmental Microbiology, July 2009, p. 4531-4538, Vol. 75, No. 13
0099-2240/09/$08.00+0 doi:10.1128/AEM.02873-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»