Biostimulation
Biostimulation is one of the most mature methods of bioremediation of hydrocarbons, yet recent advances in geophysics, stable isotope analyses, and molecular microbiology promise dramatic increases in the depth, breadth, and throughput of biostimulation s
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K. N. Timmis (ed.), Handbook of Hydrocarbon and Lipid Microbiology, DOI 10.1007/978-3-540-77587-4_355, # Springer-Verlag Berlin Heidelberg, 2010
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Biostimulation
Abstract: Biostimulation is one of the most mature methods of bioremediation of hydrocarbons, yet recent advances in geophysics, stable isotope analyses, and molecular microbiology promise dramatic increases in the depth, breadth, and throughput of biostimulation strategies. Using a systems biology approach we can now understand not only what microbes are present, but their in situ activities to trace nutrients, electron donors, electron acceptors, contaminants, and environmental stressors. Using this knowledge in combination with critical biogeochemistry, hydrology, geology, and toxicology will be enabling to develop conceptual and numerical models for the best biostimulation strategy and better long-term stewardship of the environment.
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Introduction
Bioremediation is the use of biological processes to return the environment to its original state. More realistically, the goal of bioremediation is to make the environment less toxic. In the broadest application sense, bioremediation includes use of enzymes, growth stimulants, bacteria, fungi, or plants to degrade, transform, sequester, mobilize, or contain contaminant organics, inorganics, or metals in soil, water, or air (> Fig. 1). If we accept the ‘‘Doctrine of Infallibility,’’ i.e., there is no compound known to man that microorganisms cannot degrade (Alexander, 1965), then bioremediation becomes one of the great solutions for our environmental problems. Unfortunately, while the Doctrine of Infallibility may be absolutely true, the rates of biodegradation or transformation of some compounds is so slow as to be
. Figure 1 Bioremediation Technologies used for bioremediation.
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negligible for some bioremediation purposes. In addition, the conditions (environmental or biological) that allow certain biological reactions to take place may not be obtainable in many environments (Fewson, 1988). All engineered bioremediation can be characterized as either biostimulation, i.e., the addition of nutrients, or bioaugmentation, i.e., the addition of organisms, or processes that use both. The problems with adding chemical nutrients to sediment and groundwater are fundamentally different from those of adding organisms. Simple infiltration of soil and subsequently groundwater is physically quite different in the two processes (Alfoldi, 1988). Even the smallest bacterium has different adsorption properties from chemicals. For example, clayey soils have very low porosity and may not physically allow bacteria to penetrate. These clays may also bind the microbes that are added, e.g., cationic bridges involving divalent metals and the net negative charge on the surface of the bacteria and the surface of the clay. In some soils, inorganic nutrients that are injected may precipitate metals, swell clays, change redox potentials, and conductivity, thus having a profound effect on groundwater f
