Performance of three pilot-scale hybrid constructed wetlands for total coliforms and Escherichia coli removal from primary effluent - a 2-year study in a subtropical climate

J Water Health. 2015 Jun;13(2):446-58. doi: 10.2166/wh.2014.135.

Abstract

Three pilot-scale two-stage hybrid constructed wetlands were evaluated in order to compare their efficiency for total coliforms (TCol) and Escherichia coli removal and to analyze their performances in two 1-year periods of experimentation. System I consisted of a horizontal flow (HF) constructed wetland (CW) followed by a stabilization pond. System II was also configured with a HF CW as a first stage which was then followed by a vertical flow (VF) CW as a second stage. System III was configured with a VF CW followed by a HF CW. In the first year of evaluation, the HF-VF system was the most effective for TCol removal (p < 0.05) and achieved a reduction of 2.2 log units. With regard to E. coli removal, the HF-VF and VF-HF systems were the most effective (p < 0.05) with average reductions of 3.2 and 3.8 log units, respectively. In the second year, the most effective were those with a VF component for both TCol and E. coli which underwent average reductions of 2.34-2.44 and 3.44-3.74 log units, respectively. The reduction achieved in E. coli densities, in both years, satisfy the World Health Organization guidelines that require a 3-4 log unit pathogen reduction in wastewater treatment systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Enterobacteriaceae / classification
  • Enterobacteriaceae / isolation & purification*
  • Pilot Projects
  • Time Factors
  • Waste Disposal, Fluid / methods
  • Wastewater / microbiology
  • Water Microbiology*
  • Water Purification / methods*
  • Wetlands*

Substances

  • Waste Water