Influence of the Microbial Community in the Treatment of Acidic Iron-Rich Water in Aerobic Wetland Mesocosms

Abstract

ABSTRACT Microbial communities certainly have an influence on the treatment performance of constructed wetlands (CWs); however, microbial community structure or microbial activity (MA) is rarely concurrently or comparatively quantified in relation to treatment performance. The objective of this study was to better understand the influence of the resident CW microbial community on water treatment performance in CWs. Using laboratory-scale mesocosm wetlands, several CW design variables and water chemistry variables were quantitatively and comparatively determined to assess their role in Fe(II) removal from simulated acid mine drainage (AMD). Initial AMD pH, initial AMD Fe(II) concentration, and overall wetland MA had a significant effect on an apparent first-order iron removal rate constant. Under the aerobic conditions used in this study, the presence of Phragmites australis did not have a significant effect on treatment performance. Of all the factors studied, the MA associated with the fixed microbial community had the greatest influence on the rate of iron removal. The presence of a microbiological component was shown to increase the first-order iron removal rate by a factor of 10. Following exposure to AMD, partial detachment of the fixed microbial regime was also observed, highlighting the potential consequences of AMD on the microbial community.