Changes in bacterial community structure correlate with initial operating conditions of a field-scale denitrifying fluidized bed reactor
High levels of nitrate are present in groundwater migrating from the former waste disposal ponds at the Y-12 National Security Complex in Oak Ridge, TN. A field-scale denitrifying fluidized bed reactor (FBR) was designed, constructed, and operated with ethanol as an electron donor for the removal of nitrate. After inoculation, biofilms developed on the granular activated carbon particles. Changes in the bacterial community of the FBR were evaluated with clone libraries (n=500 partial sequences) of the small-subunit rRNA gene for samples taken over a 4-month start-up period. Early phases of start-up operation were characterized by a period of selection, followed by low diversity and predominance by Azoarcus-like sequences. Possible explanations were high pH and nutrient limitations. After amelioration of these conditions, diversification increased rapidly, with the appearance of Dechloromonas, Pseudomonas, and Hydrogenophaga sequences. Changes in NO3, SO4, and pH also likely contributed to shifts in community composition. The detection of sulfate-reducing-bacteria-like sequences closely related to Desulfovibrio and Desulfuromonas in the FBR have important implications for downstream applications at the field site.
- Gentile M, Yan T, Tiquia SM, Fields MW, Nyman J, Zhou J, Criddle CS (2005) Stability in a denitrifying fluidized bed reactor. Microb Ecol (in press)Google Scholar
- Kampfer P, Schulze R, Jackel U, Malik KA, Amann R, Spring S (2005) Hydrogenophaga defluvii sp. nov. and Hydrogenophaga atypica sp. nov., isolated from activated sludge. Int J Syst Evol Microbiol 55:341–334Google Scholar
- Luo J, Wu W, Fienen MN, Jardine PM, Mehlhorn TL, Watson DB, Cirpka OA, Criddle CS, Kitanidis PK (2005) A nested-cell approach for in situ remediation. Groundwater (in press)Google Scholar
- Rittimann BE, McCarty PL (2001) Environmental biotechnology: principles and applications. McGraw-Hill, Boston, pp 126–164, pp 497–534Google Scholar
- US Environmental Protection Agency (1993) Manual: nitrogen control. EPA Office of Research and Development, Cincinnati, EPA/625/R-93/010Google Scholar