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[[File:Bioremediation at INL.jpg|thumb|A well in Idaho injects a mixture of [[sodium lactate]] and [[whey powder]] for microorganisms in a bio-remediation process.]]
[[File:Bioremediation at INL.jpg|thumb|A well in Idaho injects a mixture of [[sodium lactate]] and [[whey powder]] for microorganisms in a bio-remediation process.]]
'''Bioremediation''' is used to treat contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants. In many cases, bioremediation is less expensive and more sustainable than other remediation alternatives <ref>{{Cite book|url=https://www.worldcat.org/oclc/28851125|title=Handbook of bioremediation|date=1994|publisher=Lewis Publishers|others=Norris, Robert D., Matthews, John E., 1937-|isbn=1566700744|location=Boca Raton, FL|oclc=28851125}}</ref>.  Biological treatment is a similar approach used to treat wastes including wastewater, industrial waste and solid waste.  Most bioremediation processes involve oxidation-reduction reactions where either an electron acceptor (commonly oxygen) is added to stimulate oxidation of a reduced pollutant (e.g. hydrocarbons) or an electron donor (commonly an organic substrate) is added to reduce oxidized pollutants (nitrate, [[perchlorate]], oxidized metals, chlorinated solvents, explosives and propellants) <ref>{{Cite book|title=Introduction to In Situ Bioremediation of Groundwater|last=|first=|publisher=US Environmental Protection Agency|year=2013|isbn=|location=https://nepis.epa.gov/Exe/ZyNET.exe/P100K804.txt?ZyActionD=ZyDocument&Client=EPA&Index=2011%20Thru%202015%7C1995%20Thru%201999%7C1981%20Thru%201985%7C2006%20Thru%202010%7C1991%20Thru%201994%7C1976%20Thru%201980%7C2000%20Thru%202005%7C1986%20Thru%201990%7CPrior%20to%201976%7CHardcopy%20Publications&Docs=&Query=542-R-13-018&Time=&EndTime=&SearchMethod=2&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5CZYFILES%5CINDEX%20DATA%5C11THRU15%5CTXT%5C00000011%5CP100K804.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=15&FuzzyDegree=0&ImageQuality=r85g16/r85g16/x150y150g16/i500&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x|pages=}}</ref>. In both these approaches, additional nutrients, vitamins, minerals, and pH buffers may be added to optimize conditions for the microorganisms. In some cases, specialized microbial cultures are added (bioaugmentation) to further enhance biodegradation.  Some examples of bioremediation related technologies are [[phytoremediation]], [[mycoremediation]], [[bioventing]], [[bioleaching]], [[landfarming]], [[bioreactor]], [[composting]], [[bioaugmentation]], [[rhizofiltration]], and [[biostimulation]].
'''Bioremediation''' is a natural process that involves the use of biological entities to neutralize the contaminated site.<ref>{{cite web|url=http://ei.cornell.edu/biodeg/bioremed/|title=Environmental Inquiry - Bioremediation|publisher=}}</ref> According to the United States EPA, bioremediation is a "treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non toxic substances". Technologies can be generally classified as ''[[in situ]]'' or ''[[ex situ]]. In situ'' bioremediation involves treating the contaminated material at the site, while ''ex situ'' involves the removal of the contaminated material to be treated elsewhere. Some examples of bioremediation related technologies are [[phytoremediation]], [[mycoremediation]], [[bioventing]], [[bioleaching]], [[landfarming]], [[bioreactor]], [[composting]], [[bioaugmentation]], [[rhizofiltration]], and [[biostimulation]].


Most bioremediation processes involve oxidation-reduction ([[Redox]]) reactions where a chemical species donates an electron ([[electron donor]]) to a different species that accepts the electron ([[electron acceptor]]).  During this process, the electron donor is said to be oxidized while the electron acceptor is reduced.  Common electron acceptors in bioremediation processes include [[oxygen]], [[nitrate]], [[manganese]] (III and IV), [[iron]] (III), [[sulfate]], [[carbon dioxide]] and some pollutants (chlorinated solvents, explosives, oxidized metals, and radionuclides).  Electron donors include sugars, fats, alcohols, natural organic material, fuel hydrocarbons and a variety of reduced organic pollutants.  The [[redox potential]] for common biotransformation reactions is shown in the table.  
Bioremediation may occur on its own (natural attenuation or intrinsic bioremediation) or may only effectively occur through the addition of fertilizers, oxygen, etc., that help in enhancing the growth of the pollution-eating microbes within the medium (biostimulation). For example, the [[US Army Corps of Engineers]] demonstrated that windrowing and [[aeration]] of [[petroleum]]-[[soil contamination|contaminated soils]] enhanced bioremediation using the technique of [[landfarming]].<ref>Mann, D. K., T. M. Hurt, E. Malkos, J. Sims, S. Twait and G. Wachter. 1996. Onsite treatment of petroleum, oil, and lubricant (POL)-contaminated soils at Illinois Corps of Engineers lake sites. US Army Corps of Engineers Technical Report No. A862603 (71pages).</ref> Depleted soil nitrogen status may encourage [[biodegradation]] of some nitrogenous organic chemicals,<ref>{{cite journal | last1 = Sims | first1 = G.K. | year = 2006 | title = Nitrogen Starvation Promotes Biodegradation of N-Heterocyclic Compounds in Soil | url = | journal = Soil Biology & Biochemistry | volume = 38 | pages = 2478–2480 | doi=10.1016/j.soilbio.2006.01.006}}</ref> and soil materials with a high capacity to adsorb pollutants may slow down biodegradation owing to limited [[bioavailability]] of the chemicals to microbes.<ref>{{cite journal | last1 = O'Loughlin | first1 = E. J | last2 = Traina | first2 = S. J. | last3 = Sims | first3 = G. K. | year = 2000 | title = Effects of sorption on the biodegradation of 2-methylpyridine in aqueous suspensions of reference clay minerals | journal = Environ. Toxicol. and Chem | volume = 19 | pages = 2168–2174 | doi=10.1002/etc.5620190904}}</ref> 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. Microorganisms used to perform the function of bioremediation are known as '''bioremediators'''.

However, not all contaminants are easily treated by bioremediation using microorganisms. For example, [[heavy metals]] such as [[cadmium]] and [[lead]] are not readily absorbed or captured by microorganisms. A recent experiment, however, suggests that fish bones have some success absorbing lead from contaminated soil.<ref>{{cite journal |journal=Environmental Health Perspectives|title=Remediating Soil Lead with Fishbones|date=January 2012|author=Kris S. Freeman|pmc=3261960|pmid=22214821|doi=10.1289/ehp.120-a20a|volume=120|pages=A20–1}}</ref><ref>{{cite web | url=http://coastguard.dodlive.mil/2012/07/battling-lead-contamination-one-fish-bone-at-a-time/ | title=Battling lead contamination, one fish bone at a time | work=Coast Guard Compass | date=July 9, 2012 }}</ref> Bone char has been shown to bioremediate small amounts of [[cadmium]], [[copper]], and [[zinc]].<ref>{{cite journal|title=Chemical fixation of metals in soil using bone char and assessment of the soil genotoxicity|date=February 2007|author=Huan Jing Ke Xue|pmid=17489175|volume=28|journal=Huan Jing Ke Xue|pages=232–7}}</ref> A recent experiment suggests that the removals of pollutants (nitrate, silicate, chromium and sulphide) from tannery wastewater were studied in batch experiments using marine microalgae.<ref>{{cite web |url=http://www.scitechnol.com/bioremediation-of-tannery-wastewater-using-immobilized-marine-microalga-tetraselmis-sp-experimental-studies-and-pseudosecond-order-kinetics-Sp6P.php?article_id=3505 |title=marine Biology and oceanography |author=Adam s |deadurl=yes |archiveurl=https://web.archive.org/web/20160304130419/http://www.scitechnol.com/bioremediation-of-tannery-wastewater-using-immobilized-marine-microalga-tetraselmis-sp-experimental-studies-and-pseudosecond-order-kinetics-Sp6P.php?article_id=3505 |archivedate=2016-03-04 |df= }}</ref> The assimilation of metals such as [[mercury (element)|mercury]] into the [[food chain]] may worsen matters. [[Phytoremediation]] is useful in these circumstances because natural plants or [[transgenic plant]]s are able to [[bioaccumulate]] these toxins in their above-ground parts, which are then harvested for removal.<ref>{{cite journal | author=Meagher, RB | title=Phytoremediation of toxic elemental and organic pollutants | journal=Current Opinion in Plant Biology | volume=3 | issue=2 | year=2000 | pages=153–162 | pmid=10712958 | doi=10.1016/S1369-5266(99)00054-0}}</ref> The heavy metals in the harvested biomass may be further concentrated by incineration or even recycled for industrial use. Some damaged artifacts at museums contain microbes which could be specified as bio remediating agents.<ref>{{cite journal|title=Microorganisms Attack Synthetic Polymers in Items Representing Our Cultural Heritage |author1=Francesca Cappitelli|author2=Claudia Sorlini|journal=Applied and Environmental Microbiology |date=2008 |volume=74 |pmc=2227722|pmid=18065627|doi=10.1128/AEM.01768-07|pages=564–9}}</ref> In contrast to this situation, other contaminants, such as aromatic hydrocarbons as are common in petroleum, are relatively simple targets for microbial degradation, and some soils may even have some capacity to autoremediate, as it were, owing to the presence of autochthonous microbial communities capable of degrading these compounds.<ref name="Olapade 2014">{{cite journal|last1=Olapade |first1=OA |last2=Ronk |first2=AJ |title=Isolation, Characterization and Community Diversity of Indigenous Putative Toluene-Degrading Bacterial Populations with Catechol-2,3-Dioxygenase Genes in Contaminated Soils|journal=Microbial Ecology |date=2014|volume=69 |pmid=25052383|doi=10.1007/s00248-014-0466-6|pages=59–65}}</ref>

The elimination of a wide range of pollutants and wastes from the environment requires increasing our understanding of the relative importance of different pathways and regulatory networks to [[carbon flux]] in particular environments and for particular compounds, and they will certainly accelerate the development of bioremediation technologies and [[biotransformation]] processes.<ref name=Diaz>{{cite book | author = Diaz E (editor). | title = Microbial Biodegradation: Genomics and Molecular Biology | edition = 1st | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/biod | id =http://www.horizonpress.com/biod | isbn = 1-904455-17-4}}</ref>

==Genetic engineering approaches==
The use of [[genetic engineering]] to create organisms specifically designed for bioremediation has great potential.<ref>{{cite journal | author=Lovley, DR | title=Cleaning up with genomics: applying molecular biology to bioremediation | journal=Nature Reviews Microbiology | year=2003 | volume=1 | issue=1 | pages=35&ndash;44 | pmid=15040178 | doi=10.1038/nrmicro731}}</ref> The [[bacteria|bacterium]] ''[[Deinococcus radiodurans]]'' (the most [[radioresistance|radioresistant]] organism known) has been modified to consume and digest [[toluene]] and [[ion]]ic [[mercury (element)|mercury]] from highly radioactive nuclear waste.<ref>{{cite journal |vauthors=Brim H, McFarlan SC, Fredrickson JK, Minton KW, Zhai M, Wackett LP, Daly MJ | title=Engineering Deinococcus radiodurans for metal remediation in radioactive mixed waste environments | journal=Nature Biotechnology | year=2000 | volume=18 | issue=1 | pages=85&ndash;90 | pmid=10625398 | doi=10.1038/71986}}</ref>
Releasing genetically augmented organisms into the environment may be problematic as tracking them can be difficult; bioluminescence genes from other species may be inserted to make this easier.<ref name="Irvine">{{cite book|url=https://books.google.com/books?id=oLNtgk_VKXsC&pg=PA81&lpg=PA81&dq=Bioremediation+of+gypsum&source=bl&ots=qIBjEbqi9W&sig=bNl1WDUN_P0CyHhjztQZovSZwW0&hl=en&sa=X&ei=YdIZVLPsD8ecyASzsYG4Bw&ved=0CDUQ6AEwAw#v=onepage&q=Bioremediation%20of%20gypsum&f=false|title=Bioremediation Technologies: Principles and Practice|author1=Robert L. Irvine|author2=Subhas K. Sikdar}}</ref> {{rp|135}}

⚫
==Advantages==
⚫
There are a number of cost/efficiency advantages to bioremediation, which can be employed in areas that are inaccessible without [[Earthworks (engineering)|excavation]].<ref>{{Cite web|title = Why Bioremediation|url = http://www.jrwbioremediation.com/whybioremediation.html|website = JRW Bioremediation|accessdate = 2016-05-02}}</ref> 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 [[concentration]]s after a long time allowing for acclimation. This is typically much less expensive than excavation followed by disposal elsewhere, [[incineration]] or other ''ex situ'' treatment strategies, and reduces or eliminates the need for "pump and treat", a practice common at sites where hydrocarbons have contaminated clean groundwater. Using archaea for bioremediation of hydrocarbons also has the advantage of breaking down contaminants at the molecular level, as opposed to simply chemically dispersing the contaminant.<ref>{{Cite web|title = Archaea Effectiveness, Benefits - Akaya|url = http://www.akayaenvironmental.com/how-it-works.html|website = Akaya|accessdate = 2015-09-10}}</ref>

==Monitoring bioremediation==
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]]). This table shows the (decreasing) biological breakdown rate as function of the redox potential.
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==Aerobic Bioremediation==
This, by itself and at a single site, gives little information about the process of [[Environmental remediation|remediation]].
Aerobic bioremediation is the most common form of oxidative bioremediation process where oxygen is provided as the electron acceptor for oxidation of [[petroleum]], [[Polycyclic aromatic hydrocarbon|polyaromatic hydrocarbons]] (PAHs), [[phenols]], and other reduced pollutants. Oxygen is generally the preferred electron acceptor because of the higher energy yield and because oxygen is required for some enzyme systems to initiate the degradation process <ref>{{Cite journal|last=Thomas|first=J. M.|last2=Ward|first2=C. H.|date=1989-07-01|title=In situ biorestoration of organic contaminants in the subsurface|url=http://dx.doi.org/10.1021/es00065a004|journal=Environmental Science & Technology|volume=23|issue=7|pages=760–766|doi=10.1021/es00065a004|issn=0013-936X}}</ref>.  Numerous laboratory and field studies have shown that microorganisms can degrade a wide variety of hydrocarbons, including components of gasoline, kerosene, diesel, and jet fuel <ref>Jamison, V.W., Raymond, R.L. and Hudson, J.O., 1975. Biodegradation of high-octane gasoline in groundwater. ''Dev. Ind. Microbiol'', ''16'', pp.305-312.</ref><ref>Lee, M.D., R.C. Borden, J.T. Wilson, M. Thomas, P.B. Bedient, and C.H.Ward. 1988. Biorestoration of organic contaminated aquifers. CRC Critical Reviews in Environmental Control. 18(1):629-636.</ref><ref>Litchfield, J.H., and L.C. Clark. 1973. Bacterial Activities Ln Ground Waters Containing Petroleum Products. American Petroleum Institute. Pub. No. 4211.</ref>. Under ideal conditions, the biodegradation rates of the low- to moderate-weight aliphatic, alicyclic, and aromatic compounds can be very high. As the molecular weight of the compound increases, so does the resistance to biodegradation.
# It is necessary to [[sample (statistics)|sample]] enough points on and around the contaminated site to be able to determine [[contour line|contours]] of equal redox potential. Contouring is usually done using specialised [[software]], e.g. using [[Kriging]] interpolation.

# If all the measurements of redox potential show that electron acceptors have been used up, it is in effect an [[wikt:indicator|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.
Common approaches for providing oxygen above the water table include [[landfarming]]<ref>Loehr, R.L., W.L. Jewell, J.D. Novak, W.W. Clarkson, and G.S. Friedman. 1979. Land Application of Wastes. Van Nostrand Reinhold Co., New York, NY.</ref>, [[Compost|composting]] and [[bioventing]] <ref name=":0">Hinchee, R.E., 1994. Bioventing of petroleum hydrocarbons. ''Handbook of bioremediation'', pp.39-59.</ref>. During landfarming, contaminated soils, sediments, or sludges are incorporated into the soil surface and periodically turned over (tilled) using conventional agricultural equipment to aerate the mixture<ref>Salanitro, Joseph P. "Bioremediation of petroleum hydrocarbons in soil." Advances in agronomy 72 (2001): 53-105.</ref>.  Composting accelerates pollutant biodegradation by mixing the waste to be treated with a bulking agent, forming into piles, and periodically mixed to increase oxygen transfer <ref>Cai, Quan-Ying, et al. "Bioremediation of polycyclic aromatic hydrocarbons (PAHs)-contaminated sewage sludge by different composting processes." Journal of Hazardous Materials 142.1 (2007): 535-542.</ref>. Bioventing increases oxygen transfer by inducing air flow through the unsaturated zone using a systems of blowers and air injection / extraction wells<ref name=":0" /> or using natural variations in barometric pressure to induce air flow<ref>Larson, S., 2006. ''Design document for passive bioventing''. NAVAL FACILITIES ENGINEERING COMMAND WASHINGTON DC.</ref> (larson).
# Chemical analysis should also be carried out for assessing transformations in inorganic contaminants (e.g. [[Heavy metal (chemistry)|heavy metals]], [[radionuclide]]s). Unlike organic pollutants, inorganic pollutants cannot be degraded<ref>{{cite journal| url=https://link.springer.com/article/10.1007/s11157-005-2169-4| journal=Reviews in Environmental Science and Bio/Technology|title=Developments in Bioremediation of Soils and Sediments Polluted with Metals and Radionuclides – 1. Microbial Processes and Mechanisms Affecting Bioremediation of Metal Contamination and Influencing Metal Toxicity and Transport|date=August 2005|doi=10.1007/s11157-005-2169-4|volume=4|pages=115–156}}</ref> and remediation processes can both increase and decrease their solubility and [[Bioavailability|bio-availability]]. An increase in heavy metal mobility can occur, even in reductive conditions, during ''in-situ'' bioremediation.<ref>{{cite journal| url=http://www.sciencedirect.com/science/article/pii/S0043135414007337| journal=Water Research|title=Bioremediation of contaminated marine sediments can enhance metal mobility due to changes of bacterial diversity|date= January 2015|doi=10.1016/j.watres.2014.10.035|volume=68|pages=637–650}}</ref>

⚫
==Advantages==
⚫
There are a number of cost/efficiency advantages to bioremediation, which can be employed in areas that are inaccessible without [[Earthworks (engineering)|excavation]].<ref>{{Cite web|title = Why Bioremediation|url = http://www.jrwbioremediation.com/whybioremediation.html|website = JRW Bioremediation|accessdate = 2016-05-02}}</ref> 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 [[concentration]]s after a long time allowing for acclimation. This is typically much less expensive than excavation followed by disposal elsewhere, [[incineration]] or other ''ex situ'' treatment strategies, and reduces or eliminates the need for "pump and treat", a practice common at sites where hydrocarbons have contaminated clean groundwater. Using archaea for bioremediation of hydrocarbons also has the advantage of breaking down contaminants at the molecular level, as opposed to simply chemically dispersing the contaminant.<ref>{{Cite web|title = Archaea Effectiveness, Benefits - Akaya|url = http://www.akayaenvironmental.com/how-it-works.html|website = Akaya|accessdate = 2015-09-10}}</ref>


==See also==
==See also==

Revision as of 19:59, 8 October 2017

A well in Idaho injects a mixture of sodium lactate and whey powder for microorganisms in a bio-remediation process.

Bioremediation is used to treat contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants. In many cases, bioremediation is less expensive and more sustainable than other remediation alternatives [1].  Biological treatment is a similar approach used to treat wastes including wastewater, industrial waste and solid waste.  Most bioremediation processes involve oxidation-reduction reactions where either an electron acceptor (commonly oxygen) is added to stimulate oxidation of a reduced pollutant (e.g. hydrocarbons) or an electron donor (commonly an organic substrate) is added to reduce oxidized pollutants (nitrate, perchlorate, oxidized metals, chlorinated solvents, explosives and propellants) [2]. In both these approaches, additional nutrients, vitamins, minerals, and pH buffers may be added to optimize conditions for the microorganisms. In some cases, specialized microbial cultures are added (bioaugmentation) to further enhance biodegradation.  Some examples of bioremediation related technologies are phytoremediation, mycoremediation, bioventing, bioleaching, landfarming, bioreactor, composting, bioaugmentation, rhizofiltration, and biostimulation.

Most bioremediation processes involve oxidation-reduction (Redox) reactions where a chemical species donates an electron (electron donor) to a different species that accepts the electron (electron acceptor).  During this process, the electron donor is said to be oxidized while the electron acceptor is reduced.  Common electron acceptors in bioremediation processes include oxygen, nitrate, manganese (III and IV), iron (III), sulfate, carbon dioxide and some pollutants (chlorinated solvents, explosives, oxidized metals, and radionuclides).  Electron donors include sugars, fats, alcohols, natural organic material, fuel hydrocarbons and a variety of reduced organic pollutants.  The redox potential for common biotransformation reactions is shown in the table.  

Process Reaction Redox potential (Eh in mV) 
aerobic O2 + 4e− + 4H+ → 2H2O 600 ~ 400
anaerobic
denitrification 2NO3− + 10e− + 12H+ → N2 + 6H2O 500 ~ 200
manganese IV reduction MnO2 + 2e− + 4H+ → Mn2+ + 2H2O     400 ~ 200
iron III reduction Fe(OH)3 + e− + 3H+ → Fe2+ + 3H2O 300 ~ 100
sulfate reduction SO42− + 8e− +10 H+ → H2S + 4H2O 0 ~ −150
fermentation 2CH2O → CO2 + CH4 −150 ~ −220

Aerobic Bioremediation

Aerobic bioremediation is the most common form of oxidative bioremediation process where oxygen is provided as the electron acceptor for oxidation of petroleum, polyaromatic hydrocarbons (PAHs), phenols, and other reduced pollutants. Oxygen is generally the preferred electron acceptor because of the higher energy yield and because oxygen is required for some enzyme systems to initiate the degradation process [3].  Numerous laboratory and field studies have shown that microorganisms can degrade a wide variety of hydrocarbons, including components of gasoline, kerosene, diesel, and jet fuel [4][5][6]. Under ideal conditions, the biodegradation rates of the low- to moderate-weight aliphatic, alicyclic, and aromatic compounds can be very high. As the molecular weight of the compound increases, so does the resistance to biodegradation.

Common approaches for providing oxygen above the water table include landfarming[7], composting and bioventing [8]. During landfarming, contaminated soils, sediments, or sludges are incorporated into the soil surface and periodically turned over (tilled) using conventional agricultural equipment to aerate the mixture[9].  Composting accelerates pollutant biodegradation by mixing the waste to be treated with a bulking agent, forming into piles, and periodically mixed to increase oxygen transfer [10]. Bioventing increases oxygen transfer by inducing air flow through the unsaturated zone using a systems of blowers and air injection / extraction wells[8] or using natural variations in barometric pressure to induce air flow[11] (larson).

Advantages

There are a number of cost/efficiency advantages to bioremediation, which can be employed in areas that are inaccessible without excavation.[12] 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 excavation followed by disposal elsewhere, incineration or other ex situ treatment strategies, and reduces or eliminates the need for "pump and treat", a practice common at sites where hydrocarbons have contaminated clean groundwater. Using archaea for bioremediation of hydrocarbons also has the advantage of breaking down contaminants at the molecular level, as opposed to simply chemically dispersing the contaminant.[13]

See also

References

  1. ^ Handbook of bioremediation. Norris, Robert D., Matthews, John E., 1937-. Boca Raton, FL: Lewis Publishers. 1994. ISBN 1566700744. OCLC 28851125.{{cite book}}: CS1 maint: others (link)
  2. ^ Introduction to In Situ Bioremediation of Groundwater. https://nepis.epa.gov/Exe/ZyNET.exe/P100K804.txt?ZyActionD=ZyDocument&Client=EPA&Index=2011%20Thru%202015%7C1995%20Thru%201999%7C1981%20Thru%201985%7C2006%20Thru%202010%7C1991%20Thru%201994%7C1976%20Thru%201980%7C2000%20Thru%202005%7C1986%20Thru%201990%7CPrior%20to%201976%7CHardcopy%20Publications&Docs=&Query=542-R-13-018&Time=&EndTime=&SearchMethod=2&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&UseQField=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5CZYFILES%5CINDEX%20DATA%5C11THRU15%5CTXT%5C00000011%5CP100K804.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=15&FuzzyDegree=0&ImageQuality=r85g16/r85g16/x150y150g16/i500&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x: US Environmental Protection Agency. 2013. {{cite book}}: External link in |location= (help)CS1 maint: location (link)
  3. ^ Thomas, J. M.; Ward, C. H. (1989-07-01). "In situ biorestoration of organic contaminants in the subsurface". Environmental Science & Technology. 23 (7): 760–766. doi:10.1021/es00065a004. ISSN 0013-936X.
  4. ^ Jamison, V.W., Raymond, R.L. and Hudson, J.O., 1975. Biodegradation of high-octane gasoline in groundwater. Dev. Ind. Microbiol, 16, pp.305-312.
  5. ^ Lee, M.D., R.C. Borden, J.T. Wilson, M. Thomas, P.B. Bedient, and C.H.Ward. 1988. Biorestoration of organic contaminated aquifers. CRC Critical Reviews in Environmental Control. 18(1):629-636.
  6. ^ Litchfield, J.H., and L.C. Clark. 1973. Bacterial Activities Ln Ground Waters Containing Petroleum Products. American Petroleum Institute. Pub. No. 4211.
  7. ^ Loehr, R.L., W.L. Jewell, J.D. Novak, W.W. Clarkson, and G.S. Friedman. 1979. Land Application of Wastes. Van Nostrand Reinhold Co., New York, NY.
  8. ^ a b Hinchee, R.E., 1994. Bioventing of petroleum hydrocarbons. Handbook of bioremediation, pp.39-59.
  9. ^ Salanitro, Joseph P. "Bioremediation of petroleum hydrocarbons in soil." Advances in agronomy 72 (2001): 53-105.
  10. ^ Cai, Quan-Ying, et al. "Bioremediation of polycyclic aromatic hydrocarbons (PAHs)-contaminated sewage sludge by different composting processes." Journal of Hazardous Materials 142.1 (2007): 535-542.
  11. ^ Larson, S., 2006. Design document for passive bioventing. NAVAL FACILITIES ENGINEERING COMMAND WASHINGTON DC.
  12. ^ "Why Bioremediation". JRW Bioremediation. Retrieved 2016-05-02.
  13. ^ "Archaea Effectiveness, Benefits - Akaya". Akaya. Retrieved 2015-09-10.

External links

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