Evaluation of the Effects of Bioaugmentation and Biostimulation on Natural Attenuation and Biodegradation Pathways of Chlorinated Compounds in a Tidal Wetland

Abstract

The usefulness of bioaugmentation and biostimulation in enhancing the natural attenuation of chlorinated compounds at a seep site at Aberdeen Proving Ground, MD was tested. The biodegradation of (1) a mixture of 1,1,2,2-tetrachloroethane, tetrachloroethene, and carbon tetrachloride, or (2) TeCA alone was compared in microcosms amended with chlorinated substrates alone, chlorinated substrates and electron donor, and chlorinated substrates, electron donor, and a TeCA-degrading enrichment culture. A third experiment evaluated the usefulness of H2 thresholds in determining the importance of co-metabolic and metabolic processes in biodegradation. TeCA biodegradation was significantly enhanced by bioaugmentation and biostimulation. However, the presence of other contaminants inhibited TeCA biodegradation, even in the presence of electron donors and the enrichment culture. H2 thresholds did not prove useful in determining the importance of metabolic and co-metabolic processes; however, evaluating each chlorinated compound individually provided insight regarding biodegradation pathways and the effects of electron donor substrates on degradation rates.