Pathogen Removal in Constructed Wetland Systems

5 x 107 1900

6.5 x 107 2300

4300

1800

556,000

198,000

1 x 105 15

3 x 105 26

6200

System Performance

Location Influent Effluent'

Santee, California (bullrush wetland)b Winter season (October-March) Total coliforms (number/100 mL) Bacteriophage (PFU/mL) Summer season (April-September) Total coliforms (number/100 mL) Bacteriophage (PFU/mL) Iselin, Pennsylvania (cattails and grasses)0 Winter season (November-April)

Fecal coliforms (number/100 mL) Summer season (May-October) Fecal coliforms (number/100 mL) Arcata, California (bullrush wetland)d Winter season

Fecal coliforms (number/100 mL) Summer season

Fecal coliforms (number/100 mL) Listowel, Ontario (cattails)d Winter season

Fecal coliforms (number/100 mL) Summer season

Fecal coliforms (number/100 mL)

a Undisinfected. b Gravel bed, subsurface flow. c Sand bed, subsurface flow. d Free water surface.

Source: Reed, S.C. et al., in Proceedings AWWA Water Reuse III, American Water Works Association, Denver, CO, 1985, 962-972.

1400

40 constructed wetlands in Colorado was funded by the Colorado Governor's Office of Energy Management and Conservation (2000) and performed by HDR Engineering, Inc., and ERO Resources. The performance of and deficiencies in the various systems were evaluated, and a comprehensive report is available by contacting the office listed in the references.

3.4.3 Land Treatment Systems

Because land treatment systems in the United States are typically preceded by some form of preliminary treatment or a storage pond, parasites should be of little concern. The evidence in the literature of infection of grazing animals (Reed, 1979) is due to the direct ingestion of, or irrigation with, essentially raw wastewater. The removal of bacteria and viruses in land treatment systems is due to a combination of filtration, dessication, adsorption, radiation, and predation.

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