Optimization of artificial wetland design for removal of indicator microorganisms and pathogenic protozoa

C. P. Gerba, J. A. Thurston, J. A. Falabi, P. M. Watt, M. M. Karpiscak

Research output: Contribution to journalConference articlepeer-review

55 Scopus citations


The enhancement of water quality by artificial wetland systems is increasingly being employed throughout the world. Three wetlands were studied in Tucson, AZ to evaluate their individual performance in the removal of indicator bacteria (coliforms), coliphage, and enteric pathogens (Giardia and Cryptosporidium). A duckweed-covered pond, a multi-species subsurface flow (SSF) and a multi-species surface flow (SF) wetland were studied. Removal of the larger microorganisms, Giardia and Cryptosporidium, was the greatest in the duckweed pond at 98 and 89 percent, respectively. The lowest removal occurred in the SF wetland, 73 percent for Giardia and 58 percent removal for Cryptosporidium. In contrast, the greatest removal of coliphage, total and fecal coliforms occurred in the SSF wetland, 95, 99, and 98 percent respectively, whereas the pond had the lowest removals (40, 62,and 61 percent, respectively). Sedimentation may be the primary removal mechanism within the duckweed pond since the removal was related to size, removal of the largest organisms being the greatest. However, the smaller microorganisms were removed more efficiently in the SSF wetland, which may be related to the large surface area available for adsorption and filtration. This study suggests that in order to achieve the highest treatment level of secondary unchlorinated wastewater, a combination of aquatic ponds and subsurface flow wetlands may be necessary.

Original languageEnglish (US)
Pages (from-to)363-368
Number of pages6
JournalWater Science and Technology
Issue number4-5
StatePublished - 1999
EventProceedings of the 1998 6th International Conference on Advanced Wastewater Treatment, Recycling and Reuse - Milan, Italy
Duration: Sep 14 1998Sep 16 1998


  • Constructed wetlands
  • Cryptosporidium
  • Fecal coliforms
  • Giardia

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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