Bioaugmentation
Bioaugmentation is receiving increasing attention as an approach to augment the catabolic potential at contaminated sites and enhance the biodegradation of recalcitrant priority pollutants. This chapter discusses the merits and limitations of bioaugmentat
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K. N. Timmis (ed.), Handbook of Hydrocarbon and Lipid Microbiology, DOI 10.1007/978-3-540-77587-4_356, # Springer-Verlag Berlin Heidelberg, 2010
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Bioaugmentation
Abstract: Bioaugmentation is receiving increasing attention as an approach to augment the catabolic potential at contaminated sites and enhance the biodegradation of recalcitrant priority pollutants. This chapter discusses the merits and limitations of bioaugmentation, and presents case studies and guidelines for its successful implementation as a bioremediation approach.
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Introduction
Bioaugmentation consists of the addition (augmentation) of specialized microbial cultures, which are typically grown separately under well defined conditions, to perform a specific remediation task in a given environment (in situ or in a bioreactor) (Alvarez and Illman, 2006). This approach has been utilized in agriculture since the 1800s (e.g., addition of nitrogen-fixing Rhizobium spp. to legume roots (Gentry et al., 2004) and is now increasingly being use to enhance biodegradation of recalcitrant organic pollutants in groundwater and soils. Two distinct bioaugmentation approaches have been developed. One is based on the injection of microorganisms with the desired catabolic potential to complement or replace native microorganism’s population. In this case, the selected bacteria or consortia are capable of surviving and outcompeting native microorganisms, and occupy a specific metabolic niche within the contaminated environment (Vogel and Walter, 2002). The second bioaugmentation approach consists of the addition of a large concentration of cells that act momentarily as biocatalysts and degrade a significant amount of the target contaminant before becoming inactive or perishing (Duba et al., 1996; Krumme et al., 1994). In this case the inoculated microorganisms are not capable of establishing because of inherent abiotic and biological stress found in the new environment. These include fluctuations or extreme temperature, pH, water activity, low nutrient levels toxic pollutant concentrations, and competition with indigenous microorganisms (Gentry et al., 2004). In such cases, frequent biomass re-injection is required over time because the inoculated cells are incapable of flourishing in situ. Biostimulation (i.e., addition of nutrients and other stimulatory substrates and/or electron acceptors as appropriate) is generally used concomitantly with bioaugmentation to improve survival of the added cells and/or to optimize their metabolic capabilities (> Table 1), thus resulting in robust long term biodegradation efficiency. Bioaugmentation in wastewater activated sludge systems is relatively easy to accomplish because the added microorganisms can be readily mixed in the reactor and reaction conditions can be manipulated to enhance their survival and performance (e.g., improved flocculation and settling of biomass, faster nitrification, and enhanced degradation of recalcitrant compounds). On the other hand, bioaugmentation of aquifers is more challenging and shou
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