Reintroduction of Contaminant in Groundwater Alters Bacterial Community
Abstract:Bioaugmentation, a form of bioremediation, involves addition of microbial population acclimated with the contaminant of concern to degrade contaminants in situ. During bioremediation, periodic absence of the contaminant can alter the microbial community resulting in less efficient degradation. This study investigates the effects of supplying an alternate carbon source during the contaminant absence periods and/or bacterial degrader after the absence periods on the diversity of the bacterial community and the contaminant removal efficiency when the contaminant is reintroduced. Benzene being a common groundwater contaminant was used as the model contaminant in this study. Sand columns were set up to simulate groundwater flow and benzene breakthrough experiments were conducted to investigate benzene removal efficiencies (BREs) and bacterial community changes. Two benzene absence periods (BAP) of 10 or 25 days were tested during which only deionized water with no organic carbon source or ethanol was supplied. The effect of the absence period on the removal efficiency was more prominent during the longer absence period. Columns that received bacteria immediately after the absence periods showed superior performances than those that did not. A strain with 100% identity to Pseudomonas putida disappeared during the BAP but reemerged following the reintroduction of benzene. Columns provided with an alternative carbon source (ethanol) during the BAP and/or bacterial culture helped in maintaining the bacterial community and improving the BRE. This work identified changes in the bacterial community and their responses due to contaminant absence periods.
Document Type: Research Article
Publication date: January 1, 2012
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