Bioremediation PDF

Bioremediation General Botany 209 M.K. Beals  What is Bioremediation? a branch of biotechnology employing the use of living organisms like microbes and bacteria to remove contaminants, pollutants, and toxins from soil and water. May be used to clean up environmental pro...

Bioremediation General Botany 209 M.K. Beals  What is Bioremediation? a branch of biotechnology employing the use of living organisms like microbes and bacteria to remove contaminants, pollutants, and toxins from soil and water. May be used to clean up environmental problems such as oil spills, or contaminated groundwater. Microorganisms that are capable of degrading petroleum hydrocarbons have been found to be prolific in the subsurface.the viable option mechanism that has the ability to enhance the efficacy for treating soils contaminated with PHCs (petroleum hydrocarbon). uses the microbial species to clean up soil and groundwater contaminated by discharged chemicals (i.e. heavy metals)  What is Bioremediation? a process that mostly uses microorganisms, plants or microbial or plant enzymes to detoxify contaminants in the soil and other environments. makes use of the activity of naturally occurring microorganisms o clean up contaminated sites - more specifically their ability to biodegrade contaminants. A critical factor in deciding whether bioremediation is the appropriate cleanup remedy for a site is whether the contaminants are susceptible to biodegradation by the organisms at the site (or by organisms that could be successfully grown at the site). Some compounds are more easily degraded by a wide range of organisms than others, and systems for encouraging biodegradation are better established for some compounds than for others.  In situ and Ex situ Bioremediation Application technologies are customized to specific site characteristics; Contaminated soil may be excavated for on-or off- site treatment at surface facilities (ex situ) or treated in place (in situ). environmental conditions can be paramount for effective biodegradation. Temperature, pH, salinity, nutrients, moisture and redox condition may be altered to enhance or accelerate treatment.  In situ and Ex situ Bioremediation The ideal site for in situ bioremediation is one that is as controllable and easy to interpret as the small, laboratory-incubated flask experiments used to test pollutant biodegradation. The site most amenable to bioremediation, like the lab flask, has favorable chemical characteristics and relatively uniform geology. A principal concern in determining whether the site environment is appropriate for in situ bioremediation is the type of bioremediation to be implemented.  Two Types of Bioremediation Bioremediation can be grouped into two broad types: Intrinsic and Engineered. Intrinsic bioremediation manages the innate capabilities of naturally occurring microbial communities to degrade environmental pollutants without taking any engineering steps to enhance the process. It differs from no-action alternatives in that it requires thorough documentation of the role of native microorganisms in eliminating contaminants via tests performed at field sites or on site-derived samples of soil, sediment, or water. Furthermore, the effectiveness of intrinsic bioremediation must be proven with a site-monitoring regime that routinely analyzes contaminant concentrations. The terms "natural," "passive," and ''spontaneous" bioremediation and “bioattenuation” Intrinsic bioremediation destroys contaminants without human intervention, as the population of native microbes capable of degrading the contaminant increases naturally. The process requires thorough site monitoring to demonstrate that contaminant removal is occurring.  Two types of Bioremediation Engineered bioremediation is the acceleration of microbial activities using engineered site-modification procedures, such as installation of wells to circulate fluids and nutrients to stimulate microbial growth. The principal strategy of engineered bioremediation is to isolate and control contaminated field sites so that they become in situ bioreactors. Other terms used to describe engineered bioremediation include "biorestoration" and "enhanced bioremediation. uses technology to manipulate environmental conditions, the natural conditions are less important for engineered than for intrinsic bioremediation. ”Engineered bioremediation requires installing wells and other engineering systems to circulate electron acceptors and nutrients that stimulate microbial growth.  Bioremediation In situ Ex situ natural engineered bioremediation Engineered bioaugmentation composting Biopiles anaerobic biological reductive reactive constructed slurry/aqueous dechlorination barriers wetlands bioreactors biosparging/ bioslurping  How does Bioremediation work? Bioremediation relies on stimulating the growth of certain microbes that utilize contaminants like oil, solvents, and pesticides for sources of food and energy. These microbes convert contaminants into small amounts of water, as well as harmless gases like carbon dioxide. It requires a combination of the right temperature, nutrients, and foods. The absence of these elements may prolong the cleanup of contaminants. Conditions that are unfavorable for bioremediation may be improved by adding “amendments” to the environment, such as molasses, vegetable oil, or simple air. These amendments optimize conditions for microbes to flourish, thereby accelerating the completion of the bioremediation process.  How does Bioremediation work? The process may take anywhere from several months to several years to complete, depending on variables such as the size of the contaminated area, the concentration of contaminants, temperature, soil density, and whether bioremediation will occur in situ or ex situ. Biosurfactants provide means of improving treatment by increasing the surface area of hydrophobic hydrocarbon compounds, leading to an increased exposure to microorganisms. Microbial transformation of organic contaminants normally occurs because the organisms can use the contaminants for their own growth and reproduction. Organic contaminants serve two purposes for the organisms: they provide a source of carbon, which is one of the basic building blocks of new cell constituents, and they provide electrons, which the organisms can extract to obtain energy. How Bioremediation works  Advantages of Bioremediation Bioremediation offers numerous advantages over other cleanup methods. By relying solely on natural processes, it's a relatively green method that minimizes damage to ecosystems. Bioremediation often takes place underground, where amendments and microbes can be pumped, in order to clean up contaminants in groundwater and soil. Consequently, bioremediation does not disrupt nearby communities as much as other cleanup methodologies. The bioremediation process creates relatively few harmful byproducts, mainly due to the fact that contaminants and pollutants are converted into water and harmless gases like carbon dioxide. Finally, bioremediation is cheaper than most cleanup methods, as it does not require substantial equipment or labor. By the end of 2018, the United States Environmental Protection Agency historically brought bioremediation activities to a total of 1,507 sites. Disadvantages of Bioremediation If the process is not controlled it is possible the organic contaminants may not be broken down fully resulting in toxic by-products that could be more mobile than the initial contamination. The process is sensitive to the level of toxicity and environmental conditions in the ground i.e. the conditions must be conducive to microbial activity e.g. need to consider temperature, pH etc. Field monitoring to track the rate of biodegradation of the organic contaminants is advised. If an ex-situ process is used, controlling volatile organic compounds (VOCs) may be difficult. Treatment time is typically longer than that of other remediation technologies. Range of contaminants that can be effectively treated is limited to compounds that are biodegradable. Leaves residual levels that can be too high (not meeting regulatory requirements), persistent, and/or toxic. Performance evaluations are difficult because there is not a defined level of a "clean" site and therefore performance criteria regulations are uncertain.