Download Bioremediation Technology

Bioremediation
A technology that encourages growth and reproduction of
indigenous microorganisms (bacteria and fungi) to enhance
biodegradation of organic constituents in the saturated
zone to remove pollutants from environment.
Bioremediation can effectively degrade organic constituents
dissolved in groundwater and adsorbed onto the aquifer
matrix
Generally requires a mechanism for stimulating and
maintaining the activity of the microorganisms, e.g.,
addition of an electron acceptor (oxygen, nitrate); nutrients
(nitrogen, phosphorus); and an energy source (carbon).
• Bioremediation utilizes microbes such as bacteria, fungi, yeast, and algae
that can biodegrade organic chemicals
• Biostimulation is the addition of nutrients to enhance the growth of native
microbes. Microbes bioremediate the environment as they biodegrade the
pollutant to obtain energy.
• Non-biological methods have been effectively combined with biological
methods to enhance degradation of recalcitrant pollutants.
Bioremediation Technology
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Three categories of bioremediation techniques have been identified. They involve
distinct technologies for remediation in situ and for use of biofilters and
bioreactors.
The first category, in situ land treatment-treatment of contaminated material in
place--is a method for bioremediation of contaminated soil and, to some extent, of
associated groundwater.
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The second category of bioremediation consists of biofiltration methods for treating gaseous
streams. The biofilter is a permeable organic filter that serves as a culture medium for
microorganisms. Biofilters will either collect the pollutants or biodegrade contaminants to
harmless materials. The filter is changed when the accumulating waste levels become toxic to
the microbes or when nutrients from the organic medium are depleted.
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Biofiltration is the only biological technique currently available to remediate airborne
pollutants and can remove volatile organic compounds (VOCs) from point sources only.
Bioreactors
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Bioreactors are the third and most technologically sophisticated category of
environmental bioremediation.
Bioreactors offer a much faster means of waste biodegradation than land
treatment and more control over reaction conditions and effluent quality than
simple biofilters.
Contaminants and Their Effects
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Increases in environmental contamination lead to a progressive deterioration of
environmental quality.
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The increasing size of the human population requires the need for a biological
approach to improve environmental conditions.
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Exposure to pest control and environmental chemical remediation is increasing
because environmental release of biotechnology agents is becoming more
accepted. Therefore, it is important to have reliable data on potential health
effects of these agents.
The Hanahan Problem
A successful bioremediation experiment
• The problem in Hanahan, South Carolina, in 1975, a massive leak from a
military fuel storage facility released about 80,000 gallons of kerosinebased jet fuel. Immediate and extensive recovery measures managed to
contain the spill, but could not prevent some fuel from soaking into the
permeable sandy soil and reaching the underlying water table. Soon,
ground water was leaching such toxic chemicals as benzene ,toulene from
the fuel-saturated soils and carrying them toward a nearby residential
area by 1985.
• How could contaminated ground water be kept from seeping toward the
residential area in the future?
• One possible solution was a new technology called bioremediation.
Studies by the U.S. Geological Survey (USGS) had shown that
microorganisms naturally present in the soils were actively consuming
fuel-derived toxic compounds and transforming them into harmless
carbon dioxide.
New discovery and Bioremediation success
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Bioremediation technology using microorganisms was reportedly invented by George M.
Robinson
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By "stimulating" the natural microbial community through nutrient addition, it was
theoretically possible to increase rates of biodegradation and thereby shield the residential
area from further contamination.
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In 1992, this theory was put into practice by USGS scientists. Nutrients were delivered to
contaminated soils through infiltration galleries, contaminated ground water was removed by
a series of extraction wells, and the arduous task of monitoring contamination levels began.
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By the end of 1993, contamination in the residential area had been reduced by 75 percent.
Nearer to the infiltration galleries (the source of the nutrients), the results were even better.
Ground water that once had contained more than 5,000 parts per billion (PPB) toluene now
contained no detectable contamination.
Classification
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Bioremediation technologies can be generally classified as in situ or ex situ.
• In situ bioremediation involves treating the contaminated material at the
site
ex situ involves the removal of the contaminated material to be treated
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while
elsewhere.
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Some examples of bioremediation technologies are bioventing, landfarming, bioreactor,
composting, bioaugmentation, rhizofiltration, and biostimulation.
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Bioremediation can occur on its own (natural attenuation or intrinsic bioremediation) or can
be spurred on via the addition of fertilizers to increase the bioavailability within the medium
(biostimulation). Recent advancements have also proven successful via the addition of
matched microbe strains to the medium to enhance the resident microbe population's ability
to break down contaminants.
Micro organism whose perform the function of bioremediation is known as Bioremediators
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Types of bioremediation pollutants
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Crude oil spill ,Sewage effluent,
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Chlorinated solvents,
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Pesticides, Agricultural chemicals
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Gasoline contamination, Creosote contaminants
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Crude oil spill, Sewage effluent,chlorinated solvents,pesticides,agriculture chemicals,gasoline
contamination,
heavy metals such as cadmium and lead are not readily absorbed or captured by organisms.
The assimilation of metals such as mercury into the food chain may worsen matters.
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Genetic engineering approaches
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The use of genetic engineering to create organisms specifically designed for bioremediation
has great potential.
The bacterium Deinococcus radiodurans (the most radioresistant organism known) has been
modified to consume and digest toluene and ionic mercury from highly radioactive nuclear
waste.
The microbes are ever-present in any given context—generally referred to as "normal
microbial flora".
During bioremediation (biodegradation) processes, fertilizers/nutrient supplementation is
introduced to the environments, in efforts to maximize growth and production potential.
• Phytoremediation is useful in these circumstances, because natural plants or
transgenic plants are able to bioaccumulate these toxins in their above-ground parts, which
are then harvested for removal
Myco-remediation
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is a form of bioremediation in which fungi are used to decontaminate the area. The term
mycoremediation was coined by Paul Stamets and refers specifically to the use of fungal
mycelia in bioremediation.
One of the primary roles of fungi in the ecosystem is decomposition, which is performed by
the mycelium. The mycelium secretes extracellular enzymes and acids that break down lignin
and cellulose, the two main building blocks of plant fiber. These are organic compounds
composed of long chains of carbon and hydrogen, structurally similar to many organic
pollutants. The key to mycoremediation is determining the right fungal species to target a
specific pollutant. Certain strains have been reported to successfully degrade the nerve gases
VX and sarin.
Mycofiltration is a similar or same process, using fungal mycelia to filter toxic waste and
microorganisms from water in soil.
Advantages
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There are a number of cost/efficiency advantages to bioremediation, which can be employed
in areas that are difficult to handle.
For example, hydrocarbon spills (specifically, petrol spills) or certain chlorinated solvents may
contaminate groundwater, and introducing the appropriate electron acceptor or electron
donor amendment, as appropriate, may significantly reduce contaminant concentrations
after a long time allowing for acclimation.
This is typically much less expensive than removing of contamination followed by disposal
elsewhere, incineration (fire burn) or other ex situ treatment strategies, and reduces or
eliminates the need for "pump and treat", a common practice at sites where hydrocarbons
have contaminated clean groundwater.
Monitoring bioremediation
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The process of bioremediation can be monitored indirectly by measuring the Oxidation
Reduction Potential or redox in soil and groundwater, together with pH, temperature, oxygen
content, electron acceptor/donor concentrations, and concentration of breakdown products
(e.g. carbon dioxide).
if all the measurements of redox potential show that electron acceptors have been used up,
(600 to 0 and then -150 (Eh in mV) it's in effect an indicator for total microbial activity.
Chemical analysis is also required to determine when the levels of contaminants and their
breakdown products have been reduced to below regulatory limits.
Biodegradation
• Biodegradation – Microbially catalyzed reduction
in complexity of chemicals
• Mineralization - conversion of an organic substrate
to inorganic end products
• Growth-linked metabolism - biodegradation
provides carbon and energy to support growth
• Maintenance metabolism - biodegradation not
linked to multiplication, but to obtaining carbon for
respiration to maintain cell viability; take place
only when organic carbon concentrations very low
Biodegradation Triangle
Microbial Metabolism and bioremediation
requirements
• Need nitrogen, phosphorus, sulfur, and a variety of trace
nutrients other than carbon
• Carbon is often the limiting factor for microbial
growth in most natural systems
• Acclimatization period - a period during which no
degradation of chemical is evident; also known as
adaptation or lag period. Length of acclimatization period
varies from less than 1 h to many months
• Acclimatization of a microbial population to one
substrate frequently results in the simultaneous
acclimatization to some structurally related molecules
Xenocatabolism
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is a concept in bioremediation that was introduced by Dr. Aubrey de Grey on May 29, 2007,
at the Googleplex Google TechTalks. Dr. de Grey posited that there are microbes that feed on
substances such as amyloid, cholesterol and other related substances in places that are full of
human remains, such as graveyards.
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This was based on the microbial infallibility hypothesis. He states that "the biomedical
approach would be to identify the genetic basis for that capacity, and to put one or two
genes into ourselves, thereby enhancing our own ability to break things down, and to
thereby get rid of things that we cannot naturally break down.” In order to add credibility the
concept, de Grey created an experiment using soil from a graveyard and took the bacteria
from it. He used lipofuscin, "one of the major things that accumulates indigestibly in the
body" - which some of the bacteria broke down, giving some credit to the concept.
U.S. Microbics
• is a biotech holding company. Nicknamed "Bugs", it owns several
subsidiaries that utilize its patented microbe technology. Bugs is notable
because it is the first US Corporation to build a business around the
various commercial uses for microorganisms.
• Bugs, engages through its subsidiaries in the development, manufacture,
and sale of engineered bioremediation solutions for clean up of toxic
waste releases to soil and groundwater primarily in the United States and
Mexico
Pseudomonas putida
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is a gram-negative rod-shaped saprotrophic soil bacterium. Based on 16S rRNA
analysis, P. putida has been placed in the P. putida group, to which it lends its
name[.
It is the first patented organism in the world. Because it is a living organism the
patent was disputed and brought before the United States Supreme Court in the
historic court case Diamond v. Chakrabarty which the inventor, Ananda M.
Chakrabarty, won. It demonstrates a very diverse metabolism, including the ability
to degrade organic solvents such as toluene. This ability has been put to use in
bioremediation, or the use of microorganisms to biodegrade oil. Use of P. putida is
preferable to some other Pseudomonas species capable of such degradation as it is
a safe strain of bacteria, unlike P. aeruginosa for example, which is an opportunistic
human pathogen.
Conclusions
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Bioremediation continues to be the favored approach for processing biological wastes and
avoiding microbial pathogenesis.
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Bioremediation utilizes microbes such as bacteria, fungi, yeast, algae, and some plants.
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Microbes obtain energy when they degrade the contaminant.
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Three categories of bioremediation techniques have been identified: in situ land treatmenttreatment of contaminated material in place, biofiltration, and bioreactors.
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Bioremediation is cost-efficient and helps chemical and physical methods of managing wastes
and environmental pollutants
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Bioremediation will play an increasingly important role as a result of new and emerging
techniques and processes.