Array ( [0] => {{Short description|Process used to treat contaminated media such as water and soil}} [1] => {{cs1 config|name-list-style=vanc|display-authors=6}} [2] => {{Pollution sidebar|Soil}} [3] => {{Use mdy dates|date=February 2024}} [4] => '''Bioremediation''' broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi in [[mycoremediation]], and plants in [[phytoremediation]]), living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc., in natural or artificial settings.{{cite book |vauthors = Yuvraj |chapter = Microalgal Bioremediation: A Clean and Sustainable Approach for Controlling Environmental Pollution |date=2022 |volume=1|pages=305–318| title = Innovations in Environmental Biotechnology |place=Singapore |publisher=Springer Singapore |language=en |doi=10.1007/978-981-16-4445-0_13 |isbn=978-981-16-4445-0 }} The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment. In comparison to conventional physicochemical treatment methods bioremediation may offer advantages as it aims to be sustainable, eco-friendly, cheap, and scalable. [5] => [6] => Most bioremediation is inadvertent, involving native organisms. Research on bioremediation is heavily focused on stimulating the process by inoculation of a polluted site with organisms or supplying nutrients to promote their growth. [[Environmental remediation]] is an alternative to bioremediation.{{cite web |date=June 2011 |title=Green Remediation Best Management Practices: Sites with Leaking Underground Storage Tank Systems. EPA 542-F-11-008 |url=https://www.epa.gov/sites/production/files/2015-04/documents/ust_gr_fact_sheet.pdf|publisher=EPA}} [7] => [8] => While organic pollutants are susceptible to [[biodegradation]], heavy metals cannot be degraded, but rather oxidized or reduced. Typical bioremediations involves oxidations.{{cite journal | vauthors = Duran N, Esposito E | title = Potential Applications of Oxidative Enzymes and Phenoloxidase-like Compounds in Wastewater and Soil Treatment: A Review |journal=Applied Catalysis B: Environmental [9] => |volume=1 |issue=2 |year=2022 |pages= 305–318 |doi=10.1016/S0926-3373(00)00168-5 }}{{cite book |vauthors = Singh N, Kumar A, Sharma B |title = Recent Advancement in White Biotechnology Through Fungi |series = Fungal Biology |chapter = Role of Fungal Enzymes for Bioremediation of Hazardous Chemicals |date=2019 |volume=3 |pages=237–256 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-25506-0_9 |isbn=978-3-030-25506-0 |s2cid = 210291135}} Oxidations enhance the water-solubility of organic compounds and their susceptibility to further degradation by further oxidation and hydrolysis. Ultimately biodegradation converts hydrocarbons to [[carbon dioxide]] and water. For heavy metals, bioremediation offers few solutions. Metal-containing pollutant can be removed, at least partially, with varying bioremediation techniques.{{cite journal |vauthors = Kapahi M, Sachdeva S |title = Bioremediation Options for Heavy Metal Pollution |journal = Journal of Health and Pollution |volume = 9 |issue = 24 |page = 191203 |date = December 2019 |pmid = 31893164 |pmc = 6905138 |doi = 10.5696/2156-9614-9.24.191203 }} The main challenge to bioremediations is rate: the processes are slow. [10] => [11] => Bioremediation techniques can be classified as (i) ''[[in situ]]'' techniques, which treat polluted sites directly, vs (ii) ''ex situ'' techniques which are applied to excavated materials.{{Cite journal |vauthors=Kensa VM |date=2011 |title=Bioremediation - An Overview |url=https://www.icontrolpollution.com/peer-reviewed/bioremediation-an-overview-37408.html |journal=I Control Pollution |language=en |volume=27 |issue=2 |pages=161–168 |issn=0970-2083}} In both these approaches, additional nutrients, vitamins, minerals, and pH buffers are added to enhance the growth and metabolism of the microorganisms. In some cases, specialized microbial cultures are added ([[Bioaugmentation|biostimulation]]). Some examples of bioremediation related technologies are [[phytoremediation]], [[bioventing]], bioattenuation, [[biosparging]], [[composting]] (biopiles and windrows), and [[landfarming]]. Other remediation techniques include [[thermal desorption]], [[vitrification]], [[air stripping]], [[bioleaching]], [[rhizofiltration]], and soil washing. Biological treatment, bioremediation, is a similar approach used to treat wastes including wastewater, industrial waste and solid waste. The end goal of bioremediation is to remove harmful compounds to improve soil and water quality.{{Cite journal |vauthors = Canak S, Berezljev L, Borojevic K, Asotic J, Ketin S |date=2019 |title=Bioremediation and "green chemistry" |url= https://www.researchgate.net/publication/332318816 |journal=Fresenius Environmental Bulletin |volume=28 |issue=4 |pages=3056–3064 |via=}} [12] => [13] => == ''In situ'' techniques == [14] => [[File:In Situ Bioremediation.png|thumb|Visual representation showing ''in-situ'' bioremediation. This process involves the addition of oxygen, nutrients, or microbes into contaminated soil to remove toxic pollutants. Contamination includes buried waste and underground pipe leakage that infiltrate ground water systems.{{cite journal | vauthors = Jørgensen KS |title=In Situ Bioremediation|date=2007 | journal = Advances in Applied Microbiology|volume=61|pages=285–305|publisher=Academic Press|language=en|doi=10.1016/S0065-2164(06)61008-3|pmid=17448793|isbn=978-0-12-002663-0}} The addition of oxygen removes the pollutants by producing carbon dioxide and water.]] [15] => [16] => === Bioventing === [17] => Bioventing is a process that increases the oxygen or air flow into the unsaturated zone of the soil, this in turn increases the rate of natural ''in situ'' degradation of the targeted hydrocarbon contaminant.{{cite journal | vauthors = García Frutos FJ, Escolano O, García S, Babín M, Fernández MD | title = Bioventing remediation and ecotoxicity evaluation of phenanthrene-contaminated soil | journal = Journal of Hazardous Materials | volume = 183 | issue = 1–3 | pages = 806–13 | date = November 2010 | pmid = 20800967 | doi = 10.1016/j.jhazmat.2010.07.098 }} Bioventing, an 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.{{Cite book |author=Mirza Hasanuzzaman |author2=Majeti Narasimha Vara Prasad |title=Handbook of Bioremediation|year=2020|isbn=978-0-12-819382-2|publisher=Academic Press|doi=10.1016/C2018-0-05109-9|s2cid=127409446 }} Microorganisms can degrade a wide variety of hydrocarbons, including components of gasoline, kerosene, diesel, and jet fuel. Under ideal aerobic conditions, the biodegradation rates of the low- to moderate-weight [[Aliphatic compound|aliphatic]], [[Alicyclic compound|alicyclic]], and [[Aromatic hydrocarbon|aromatic]] compounds can be very high. As molecular weight of the compound increases, the resistance to biodegradation increases simultaneously. This results in higher contaminated volatile compounds due to their high molecular weight and an increased difficulty to remove from the environment. [18] => [19] => 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).{{Cite book|url=https://www.epa.gov/sites/production/files/2015-04/documents/introductiontoinsitubioremediationofgroundwater_dec2013.pdf|title=Introduction to In Situ Bioremediation of Groundwater|publisher=US Environmental Protection Agency|year=2013|page=30}} 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. [20] => [21] => Approaches for oxygen addition below the water table include recirculating aerated water through the treatment zone, addition of pure oxygen or peroxides, and [[air sparging]]. Recirculation systems typically consist of a combination of injection wells or galleries and one or more recovery wells where the extracted groundwater is treated, oxygenated, amended with nutrients and re-injected. However, the amount of oxygen that can be provided by this method is limited by the low solubility of oxygen in water (8 to 10 mg/L for water in equilibrium with air at typical temperatures). Greater amounts of oxygen can be provided by contacting the water with pure oxygen or addition of [[hydrogen peroxide]] (H2O2) to the water. In some cases, slurries of solid calcium or magnesium peroxide are injected under pressure through soil borings. These solid peroxides react with water releasing H2O2 which then decomposes releasing oxygen. Air sparging involves the injection of air under pressure below the water table. The air injection pressure must be great enough to overcome the hydrostatic pressure of the water and resistance to air flow through the soil.{{Cite book|title=Air Sparging Design Paradigm| vauthors = Leeson A |publisher= Battelle | location = Columbus OH |year=2002| url = https://apps.dtic.mil/sti/pdfs/ADA492279.pdf| archive-url = https://web.archive.org/web/20170620003120/http://www.dtic.mil/get-tr-doc/pdf?AD=ADA492279| url-status = live| archive-date = June 20, 2017}} [22] => [23] => === Biostimulation === [24] => [[File:Bioremediation at INL.jpg|thumb|An example of biostimulation at the Snake River Plain Aquifer in Idaho. This process involves the addition of whey powder to promote the utilization of naturally present bacteria. Whey powder acts as a substrate to aid in the growth of bacteria.{{Cite journal| vauthors = Mora RH, Macbeth TW, MacHarg T, Gundarlahalli J, Holbrook H, Schiff P |date=2008|title=Enhanced bioremediation using whey powder for a trichloroethene plume in a high-sulfate, fractured granitic aquifer |journal=Remediation Journal|language=en|volume=18|issue=3|pages=7–30|doi=10.1002/rem.20168|bibcode=2008RemJ...18c...7M |issn=1520-6831}} At this site, microorganisms break down the carcinogenic compound [[trichloroethylene]] (TCE), which is a process seen in previous studies.]] [25] => [26] => Bioremediation can be carried out by bacteria that are naturally present. In biostimulation, the population of these helpful bacteria can be increased by adding nutrients.{{cite journal | vauthors = Kalantary RR, Mohseni-Bandpi A, Esrafili A, Nasseri S, Ashmagh FR, Jorfi S, Ja'fari M | title = Effectiveness of biostimulation through nutrient content on the bioremediation of phenanthrene contaminated soil | journal = Journal of Environmental Health Science & Engineering | volume = 12 | issue = 1 | pages = 143 | date = December 2014 | pmid = 25610635 | pmc = 4301987 | doi = 10.1186/s40201-014-0143-1 | bibcode = 2014JEHSE..12..143K | doi-access = free }} [27] => [28] => Bacteria can in principle be used to degrade hydrocarbons.{{cite journal | vauthors = Lee DW, Lee H, Lee AH, Kwon BO, Khim JS, Yim UH, Kim BS, Kim JJ | title = Microbial community composition and PAHs removal potential of indigenous bacteria in oil contaminated sediment of Taean coast, Korea | journal = Environmental Pollution | volume = 234 | pages = 503–512 | date = March 2018 | pmid = 29216488 | doi = 10.1016/j.envpol.2017.11.097 | bibcode = 2018EPoll.234..503L }}{{cite journal| vauthors = Chen Q, Bao B, Li Y, Liu M, Zhu B, Mu J, Chen Z |date=2020|title=Effects of marine oil pollution on microbial diversity in coastal waters and stimulating indigenous microorganism bioremediation with nutrients |journal=Regional Studies in Marine Science|language=en|volume=39|page=101395|doi=10.1016/j.rsma.2020.101395|bibcode=2020RSMS...3901395C |s2cid=225285497 |issn=2352-4855}} Specific to marine oil spills, nitrogen and phosphorus have been key nutrients in biodegradation.{{Cite journal| vauthors = Varjani SJ, Upasani VN |date=2017|title=A new look on factors affecting microbial degradation of petroleum hydrocarbon pollutants |journal=International Biodeterioration & Biodegradation|language=en|volume=120|pages=71–83|doi=10.1016/j.ibiod.2017.02.006|issn=0964-8305}} The bioremediation of hydrocarbons suffers from low rates. [29] => [30] => Bioremediation can involve the action of [[microbial consortium]]. Within the consortium, the product of one species could be the substrate for another species.{{cite book | vauthors = Paniagua-Michel J, Fathepure BZ | chapter = Microbial Consortia and Biodegradation of Petroleum Hydrocarbons in Marine Environments|date=2018 | title =Microbial Action on Hydrocarbons|pages=1–20| veditors = Kumar V, Kumar M, Prasad R |place= Singapore|publisher=Springer Singapore|language=en|doi=10.1007/978-981-13-1840-5_1|isbn=978-981-13-1839-9 }} [31] => [32] => Anaerobic bioremediation can in principle be employed to treat a range of oxidized contaminants including chlorinated [[ethylene]]s ([[Tetrachloroethylene|PCE]], [[Trichloroethylene|TCE]], [[Dichloroethene|DCE]], [[Vinyl chloride|VC)]], chlorinated [[ethane]]s ([[Trichloroethane|TCA]], [[Dichloroethane|DCA]]), chloromethanes ([[Carbon tetrachloride|CT]], [[Chloroform|CF]]), chlorinated cyclic hydrocarbons, various energetics (e.g., [[perchlorate]],{{cite book| vauthors = Coates JD, Jackson WA |title=In Situ Bioremediation of Perchlorate in Groundwater |date=2008|publisher=Springer|isbn=978-0-387-84921-8| veditors = Stroo H, Ward CH |location=New York|pages=29–53|chapter=Principles of Perchlorate Treatment|series=SERDP/ESTCP Environmental Remediation Technology|doi=10.1007/978-0-387-84921-8_3}} [[RDX]], [[TNT]]), and [[nitrate]]. This process involves the addition of an electron donor to: 1) deplete background electron acceptors including oxygen, nitrate, oxidized iron and manganese and sulfate; and 2) stimulate the biological and/or chemical reduction of the oxidized pollutants. The choice of substrate and the method of injection depend on the contaminant type and distribution in the aquifer, hydrogeology, and remediation objectives. Substrate can be added using conventional well installations, by direct-push technology, or by excavation and backfill such as [[permeable reactive barrier]]s (PRB) or biowalls.{{cite web | vauthors = Gavaskar A, Gupta N, Sass B, Janosy R, Hicks J | title = Design guidance for application of permeable reactive barriers for groundwater remediation. | publisher = Battelle | location = Columbus OH | date = March 2000 | url = https://www.researchgate.net/publication/265150942 }} Slow-release products composed of edible oils or solid substrates tend to stay in place for an extended treatment period. Soluble substrates or soluble fermentation products of slow-release substrates can potentially migrate via advection and diffusion, providing broader but shorter-lived treatment zones. The added organic substrates are first fermented to hydrogen (H2) and volatile fatty acids (VFAs). The VFAs, including acetate, lactate, propionate and butyrate, provide carbon and energy for bacterial metabolism. [33] => [34] => === Bioattenuation === [35] => During bioattenuation, biodegradation occurs naturally with the addition of nutrients or bacteria. The indigenous microbes present will determine the metabolic activity and act as a natural attenuation.{{cite book | vauthors = Ying GG | chapter = Chapter 14 - Remediation and Mitigation Strategies|date=2018 | title = Integrated Analytical Approaches for Pesticide Management|pages=207–217|publisher=Academic Press|language=en|doi=10.1016/b978-0-12-816155-5.00014-2|isbn=978-0-12-816155-5}} While there is no anthropogenic involvement in bioattenuation, the contaminated site must still be monitored. [36] => [37] => === Biosparging === [38] => Biosparging is the process of groundwater remediation as oxygen, and possible nutrients, is injected. When oxygen is injected, indigenous bacteria are stimulated to increase rate of degradation. However, biosparging focuses on saturated contaminated zones, specifically related to ground water remediation.{{cite journal| vauthors = Johnson PC, Johnson RL, Bruce CL, Leeson A |date=2001|title=Advances in In Situ Air Sparging/Biosparging |journal=Bioremediation Journal|volume=5|issue=4|pages=251–266|doi=10.1080/20018891079311|bibcode=2001BiorJ...5..251J |s2cid=131393543|issn=1088-9868}} [39] => [40] => UNICEF, power producers, bulk water suppliers, and local governments are early adopters of low cost bioremediation, such as aerobic bacteria tablets which are simply dropped into water.{{cite web |date=June 2022 |title=Ageing infrastructure gets bio boost |url=https://bedfordviewedenvalenews.co.za/494020/aging-infrastructure-to-get-bio-boost/ |publisher=CAXTON}} [41] => [42] => == ''Ex situ'' techniques == [43] => [44] => === Biopiles === [45] => Biopiles, similar to bioventing, are used to remove petroleum pollutants by introducing aerobic hydrocarbons to contaminated soils. However, the soil is excavated and piled with an aeration system. This aeration system enhances microbial activity by introducing oxygen under positive pressure or removes oxygen under negative pressure.{{cite journal | vauthors = Chen R, Zhou Y | title = Measure microbial activity driven oxygen transfer in membrane aerated biofilm reactor from supply side | journal = Environmental Research | volume = 195 | pages = 110845 | date = April 2021 | pmid = 33549616 | doi = 10.1016/j.envres.2021.110845 | s2cid = 231867176 | bibcode = 2021ER....195k0845C }} [46] => [47] => === Windrows === [48] => [[File:Shell Haven East Site - geograph.org.uk - 591937.jpg|thumb|The former Shell Haven Refinery in Standford-le-Hope which underwent bioremediation to minimize the oil contaminated site. Bioremediation techniques, such as windrows, were used to promote oxygen transfer.{{Cite book| vauthors = Waters JM, Lambert C, Reid D, Shaw R |title=Redevelopment of the former Shell Haven refinery |publisher=WIT Press|year=2002|isbn=1-85312-918-6|location=Southampton, UK|pages=77–85}} The refinery has excavated approximately 115,000 m3 of contaminated soil.]] [49] => Windrow systems are similar to compost techniques where soil is periodically turned in order to enhance aeration.{{Cite book | vauthors = Prasad S, Kannojiya S, Kumar S, Yadav KK, Kundu M, Rakshit A | chapter = Integrative Approaches for Understanding and Designing Strategies of Bioremediation. | veditors = Rakshit A, Parihar M, Sarkar B, Singh HB, Fraceto LF | chapter-url=https://books.google.com/books?id=H-IaEAAAQBAJ&q=bioremediation+windrow&pg=PA37|title=Bioremediation Science: From Theory to Practice|date=2021|publisher=CRC Press|isbn=978-1-000-28046-3|language=en}} This periodic turning also allows contaminants present in the soil to be uniformly distributed which accelerates the process of bioremediation.{{cite journal | vauthors = Azubuike CC, Chikere CB, Okpokwasili GC | title = Bioremediation techniques-classification based on site of application: principles, advantages, limitations and prospects | journal = World Journal of Microbiology & Biotechnology | volume = 32 | issue = 11 | page = 180 | date = November 2016 | pmid = 27638318 | pmc = 5026719 | doi = 10.1007/s11274-016-2137-x }} [50] => [51] => === Landfarming === [52] => {{Main|Landfarming}} [53] => [[Landfarming]], or land treatment, is a method commonly used for sludge spills. This method disperses contaminated soil and aerates the soil by cyclically rotating.{{cite book | vauthors = Kumar V, Shahi SK, Singh S | chapter = Bioremediation: An Eco-sustainable Approach for Restoration of Contaminated Sites|date=2018 | veditors = Singh J, Sharma D, Kumar G, Sharma NR | title = Microbial Bioprospecting for Sustainable Development|pages=115–136|place=Singapore|publisher=Springer|language=en|doi=10.1007/978-981-13-0053-0_6|isbn=978-981-13-0053-0 }} This process is an above land application and contaminated soils are required to be shallow in order for microbial activity to be stimulated. However, if the contamination is deeper than 5 feet, then the soil is required to be excavated to above ground.{{cite web | publisher = United States Environmental Protection Agency (USEPA) | date = 2017 | title = How To Evaluate Alternative Cleanup Technologies For Underground Storage Tank Sites. A Guide For Corrective Action Plan Reviewers. | work = EPA 510-B-17-003 | url = https://www.epa.gov/sites/production/files/2014-03/documents/tum_ch5.pdf }} While it is an ''ex situ'' technique, it can also be considered an ''in situ'' technique as Landfarming can be performed at the site of contamination.{{cite journal | vauthors = Azubuike CC, Chikere CB, Okpokwasili GC | title = Bioremediation techniques-classification based on site of application: principles, advantages, limitations and prospects | journal = World Journal of Microbiology & Biotechnology | volume = 32 | issue = 11 | pages = 180 | date = November 2016 | pmid = 27638318 | pmc = 5026719 | doi = 10.1007/s11274-016-2137-x }} [54] => [55] => == ''In situ'' vs. ''Ex situ'' == [56] => ''Ex situ'' techniques are often more expensive because of excavation and transportation costs to the treatment facility, while i''n situ'' techniques are performed at the site of contamination so they only have installation costs. While there is less cost there is also less of an ability to determine the scale and spread of the pollutant. The pollutant ultimately determines which bioremediation method to use. The depth and spread of the pollutantare other important factors.{{cite journal | vauthors = Azubuike CC, Chikere CB, Okpokwasili GC | title = Bioremediation techniques-classification based on site of application: principles, advantages, limitations and prospects | journal = World Journal of Microbiology & Biotechnology | volume = 32 | issue = 11 | pages = 180 | date = November 2016 | pmid = 27638318 | doi = 10.1007/s11274-016-2137-x | pmc = 5026719 }} [57] => [58] => ==Heavy metals== [59] => Heavy metals are introduced into the environment by both anthropogenic activities and natural factors. Anthropogenic activities include industrial emissions, electronic waste, and mining. Natural factors include mineral weathering, soil erosion, and forest fires. Heavy metals including cadmium, chromium, lead and uranium are unlike organic compounds and cannot be biodegraded. However, bioremediation processes can potentially be used to minimize the mobility of these material in the subsurface, lowering the potential for human and environmental exposure.{{Cite journal| vauthors = Ghosh M, Singh SP |date= July 2005|title=A Review on Phytoremediation of Heavy Metals and Utilization of Its Byproducts |journal=Asian Journal on Energy and Environment|volume=6|issue=4|pages=214–231|doi= 10.15666/AEER/0301_001018|s2cid= 15886743|issn=|doi-access=free}} Heavy metals from these factors are predominantly present in water sources due to runoff where it is uptake by marine fauna and flora. [60] => [61] => [[Hexavalent chromium]] (Cr[VI]) and uranium (U[VI]) can be reduced to less mobile and/or less toxic forms (e.g., Cr[III], U[IV]). Similarly, reduction of sulfate to sulfide (sulfidogenesis) can be used to immobilize certain metals (e.g., [[zinc]], [[cadmium]]). [62] => [63] => The mobility of certain metals including chromium (Cr) and uranium (U) varies depending on the oxidation state of the material.{{Cite book|url=https://enviro.wiki/images/c/c1/USEPA-2007-MNA_of_Inorganic_Contaminants_in_GW%2C_Vol_1_Technical_Basis_for_Assessment.pdf|title=Monitored natural attenuation of inorganic contaminants in groundwater, Volume 1 Technical basis for assessment| vauthors = Ford RG, Wilkin RT, Puls RW |publisher=U.S. Environmental Protection Agency, EPA/600/R-07/139|year=2007|oclc=191800707}} Microorganisms can be used to lower the toxicity and mobility of chromium by reducing hexavalent chromium, Cr(VI) to trivalent Cr(III).{{Cite book|url=https://enviro.wiki/images/3/3a/USEPA-2007-MNA_of_Inorganic_Contaminants_in_GW%2C_Vol_2.pdf|title=Monitored Natural Attenuation of Inorganic Contaminants in Groundwater, Volume 2 - Assessment for Non-Radionulcides Including Arsenic, Cadmium, Chromium, Copper, Lead, Nickel, Nitrate, Perchlorate, and Selenium | vauthors = Ford RG, Wilkin RT, Puls RW |publisher=USEPA|year=2007}} Reduction of the more mobile U(VI) species affords the less mobile U(IV) derivatives.{{cite journal | vauthors = Williams KH, Bargar JR, Lloyd JR, Lovley DR | title = Bioremediation of uranium-contaminated groundwater: a systems approach to subsurface biogeochemistry | journal = Current Opinion in Biotechnology | volume = 24 | issue = 3 | pages = 489–97 | date = June 2013 | pmid = 23159488 | doi = 10.1016/j.copbio.2012.10.008 }}{{Cite book|url=https://enviro.wiki/images/0/05/USEPA-2010-MNA_of_Inorganic_Contaminants_in_GW%2C_Vol_3.pdf|title=Monitored natural attenuation of inorganic contaminants in groundwater, Volume 3 Assessment for Radionuclides Including Tritium, Radon, Strontium, Technetium, Uranium, Iodine, Radium, Thorium, Cesium, and Plutonium-Americium | vauthors = Ford RG, Wilkin RT, Puls RW |publisher=U.S. Environmental Protection Agency, EPA/600/R-10/093|year=2007}} Microorganisms are used in this process because the reduction rate of these metals is often slow in the absence of microbial interactions{{Cite book|title=Bioremediation of Metals and Radionuclides: What It Is and How It Works | edition = 2nd | vauthors = Palmisano A, Hazen T |date=2003|publisher=Lawrence Berkeley National Laboratory|oclc=316485842}} Research is also underway to develop methods to remove metals from water by enhancing the sorption of the metal to cell walls. This approach has been evaluated for treatment of cadmium,{{cite journal | vauthors = Ansari MI, Malik A | title = Biosorption of nickel and cadmium by metal resistant bacterial isolates from agricultural soil irrigated with industrial wastewater | journal = Bioresource Technology | volume = 98 | issue = 16 | pages = 3149–53 | date = November 2007 | pmid = 17166714 | doi = 10.1016/j.biortech.2006.10.008 | bibcode = 2007BiTec..98.3149A }} chromium,{{cite journal | vauthors = Durán U, Coronado-Apodaca KG, Meza-Escalante ER, Ulloa-Mercado G, Serrano D | title = Two combined mechanisms responsible to hexavalent chromium removal on active anaerobic granular consortium | journal = Chemosphere | volume = 198 | pages = 191–197 | date = May 2018 | pmid = 29421729 | doi = 10.1016/j.chemosphere.2018.01.024 | bibcode = 2018Chmsp.198..191D }} and lead.{{cite journal | vauthors = Tripathi M, Munot HP, Shouche Y, Meyer JM, Goel R | title = Isolation and functional characterization of siderophore-producing lead- and cadmium-resistant Pseudomonas putida KNP9 | journal = Current Microbiology | volume = 50 | issue = 5 | pages = 233–7 | date = May 2005 | pmid = 15886913 | doi = 10.1007/s00284-004-4459-4 | s2cid = 21061197 }} Genetically modified bacteria has also been explored for use in sequestration of Arsenic.{{cite book | vauthors = Yam HM, Leong S, Qiu X, Zaiden N | title = Irc-Set 2020 | chapter = Bioremediation of Arsenic-Contaminated Water Through Application of Bioengineered Shewanella oneidensis | volume = 1 | pages = 559–574 | date = May 2021 | doi = 10.1007/978-981-15-9472-4_49 | isbn = 978-981-15-9471-7 | s2cid = 236650675 }} [[Phytoextraction process]]es concentrate contaminants in the biomass for subsequent removal. [64] => [65] => Metal extractions can in principle be performed in situ or ex situ where in situ is preferred since it is less expensive to excavate the substrate.{{cite journal | vauthors = Azubuike CC, Chikere CB, Okpokwasili GC | title = Bioremediation techniques-classification based on site of application: principles, advantages, limitations and prospects | journal = World Journal of Microbiology & Biotechnology | volume = 32 | issue = 11 | pages = 180 | date = November 2016 | pmid = 27638318 | pmc = 5026719 | doi = 10.1007/s11274-016-2137-x }} [66] => [67] => Bioremediation is not specific to metals. In 2010 there was a [[Deepwater Horizon oil spill|massive oil spill in the Gulf of Mexico]]. Populations of bacteria and [[archaea]] were used to rejuvenate the coast after the oil spill. These microorganisms over time have developed metabolic networks that can utilize hydrocarbons such as oil and petroleum as a source of carbon and energy.{{cite journal | vauthors = Fathepure BZ | title = Recent studies in microbial degradation of petroleum hydrocarbons in hypersaline environments | language = English | journal = Frontiers in Microbiology | volume = 5 | pages = 173 | date = 2014-01-01 | pmid = 24795705 | pmc = 4005966 | doi = 10.3389/fmicb.2014.00173 | doi-access = free }} Microbial bioremediation is a very effective modern technique for restoring natural systems by removing toxins from the environment. [68] => [69] => == Pesticides == [70] => Of the many ways to deal with pesticide contamination, bioremediation promises to be more effective.{{cite journal | vauthors = Nie J, Sun Y, Zhou Y, Kumar M, Usman M, Li J, Shao J, Wang L, Tsang DC | title = Bioremediation of water containing pesticides by microalgae: Mechanisms, methods, and prospects for future research | journal = The Science of the Total Environment | volume = 707 | pages = 136080 | date = March 2020 | pmid = 31869621 | doi = 10.1016/j.scitotenv.2019.136080 | bibcode = 2020ScTEn.707m6080N }} Many sites around the world are contaminated with agrichemicals. {{cite journal | vauthors = Alvarez A, Saez JM, Davila Costa JS, Colin VL, Fuentes MS, Cuozzo SA, Benimeli CS, Polti MA, Amoroso MJ | title = Actinobacteria: Current research and perspectives for bioremediation of pesticides and heavy metals | journal = Chemosphere | volume = 166 | pages = 41–62 | date = January 2017 | pmid = 27684437 | doi = 10.1016/j.chemosphere.2016.09.070 | bibcode = 2017Chmsp.166...41A }} These agrichemicals often resist biodegradation, by design.{{Cite journal | vauthors = Mohapatra D, Rath SK, Mohapatra PK |date=2022-05-02 |title=Soil Fungi for Bioremediation of Pesticide Toxicants: A Perspective |journal=Geomicrobiology Journal |language=en |volume=39 |issue=3–5 |pages=352–372 |doi=10.1080/01490451.2021.2019855 |bibcode=2022GmbJ...39..352M |issn=0149-0451}}{{cite journal | vauthors = Nie J, Sun Y, Zhou Y, Kumar M, Usman M, Li J, Shao J, Wang L, Tsang DC | title = Bioremediation of water containing pesticides by microalgae: Mechanisms, methods, and prospects for future research | journal = The Science of the Total Environment | volume = 707 | pages = 136080 | date = March 2020 | pmid = 31869621 | doi = 10.1016/j.scitotenv.2019.136080 | bibcode = 2020ScTEn.707m6080N }} Harming all manners of organic life with long term health issues such as cancer, rashes, blindness, paralysis, and mental illness. An example is [[Lindane]] which was a commonly used insecticide in the 20th century. Long time exposure poses a serious threat to humans and the surrounding ecosystem. Lindane reduces the potential of beneficial bacteria in the soil such as nitrogen fixation cyanobacteria. As well as causing central nervous system issues in smaller mammals such as seizures, dizziness, and even death. What makes it so harmful to these organisms is how quickly distributed it gets through the brain and fatty tissues. While Lindane has been mostly limited to specific use, it is still produced and used around the world.{{cite journal | vauthors = Chaurasia AK, Adhya TK, Apte SK | title = Engineering bacteria for bioremediation of persistent organochlorine pesticide lindane (γ-hexachlorocyclohexane) | journal = Bioresource Technology | volume = 149 | pages = 439–445 | date = December 2013 | pmid = 24135568 | doi = 10.1016/j.biortech.2013.09.084 | bibcode = 2013BiTec.149..439C }} [71] => [72] => [[Actinomycetota|Actinobacteria]] has been a promising candidate ''in situ'' technique specifically for removing pesticides. When certain strains of Actinobacteria have been grouped together, their efficiency in degrading pesticides has enhanced. As well as being a reusable technique that strengthens through further use by limiting the migration space of these cells to target specific areas and not fully consume their cleansing abilities. Despite encouraging results, Actinobacteria has only been used in controlled lab settings and will need further development in finding the cost effectiveness and scalability of use.{{cite journal | vauthors = Alvarez A, Saez JM, Davila Costa JS, Colin VL, Fuentes MS, Cuozzo SA, Benimeli CS, Polti MA, Amoroso MJ | title = Actinobacteria: Current research and perspectives for bioremediation of pesticides and heavy metals | journal = Chemosphere | volume = 166 | pages = 41–62 | date = January 2017 | pmid = 27684437 | doi = 10.1016/j.chemosphere.2016.09.070 | bibcode = 2017Chmsp.166...41A }} [73] => [74] => == Limitations of bioremediation == [75] => Bioremediation can be used to mineralize organic pollutants, to partially transform the pollutants, or alter their mobility. [[Heavy metals]] and [[Agricultural pollution#Radioactive elements|radionuclides]] generally cannot be biodegraded, but can be bio-transformed to less mobile forms.{{cite journal| vauthors = Juwarkar AA, Singh SK, Mudhoo A |year=2010|title=A comprehensive overview of elements in bioremediation|journal=Reviews in Environmental Science and Bio/Technology|volume=9|issue=3|pages=215–88 |doi=10.1007/s11157-010-9215-6|bibcode=2010RESBT...9..215J |s2cid=85268562}}{{cite journal |doi=10.1016/S0960-8524(99)00144-3 |title=Factors limiting bioremediation technologies |journal=Bioresource Technology |volume=74 |pages=63–7 |year=2000 | vauthors = Boopathy R |issue=1 |bibcode=2000BiTec..74...63B |s2cid=1027603 }}{{cite book|title=Encyclopedia of toxicology| vauthors = Wexler P |date=2014|publisher=Academic Press Inc|isbn=978-0-12-386454-3|edition=3rd|location=San Diego, Ca|page=489}} In some cases, microbes do not fully mineralize the pollutant, potentially producing a more toxic compound. For example, under anaerobic conditions, the [[Reductive dechlorination|reductive dehalogenation]] of [[Trichloroethylene|TCE]] may produce [[Dichloroethene|dichloroethylene]] (DCE) and [[vinyl chloride]] (VC), which are suspected or known [[carcinogen]]s. However, the microorganism ''[[Dehalococcoides]]'' can further reduce DCE and VC to the non-toxic product ethene.{{cite journal | vauthors = Maymó-Gatell X, Chien Y, Gossett JM, Zinder SH | title = Isolation of a bacterium that reductively dechlorinates tetrachloroethene to ethene | journal = Science | volume = 276 | issue = 5318 | pages = 1568–71 | date = June 1997 | pmid = 9171062 | doi = 10.1126/science.276.5318.1568 }} The molecular pathways for bioremediation are of considerable interest. In addition, knowing these pathways will help develop new technologies that can deal with sites that have uneven distributions of a mixture of contaminants.{{cite journal| vauthors = Vidali M |year=2001|title=Bioremediation. An overview|url=https://www.iupac.org/publications/pac/pdf/2001/pdf/7307x1163.pdf|journal=Pure and Applied Chemistry|volume=73|issue=7|pages=1163–72|doi=10.1351/pac200173071163|s2cid=18507182}} [76] => [77] => Biodegradation requires microbial population with the metabolic capacity to degrade the pollutant. The biological processes used by these microbes are highly specific, therefore, many environmental factors must be taken into account and regulated as well. It can be difficult to extrapolate the results from the small-scale test studies into big field operations. In many cases, bioremediation takes more time than other alternatives such as [[Landfill|land filling]] and [[incineration]]. Another example is bioventing, which is inexpensive to bioremediate contaminated sites, however, this process is extensive and can take a few years to decontaminate a site.{{Cite journal|vauthors=Sharma J|date=2019|title=Advantages and Limitations of In Situ Methods of Bioremediation|journal=Recent Adv Biol Med|language=en|volume=5|issue=2019|page=10941|doi=10.18639/RABM.2019.955923|doi-broken-date=February 12, 2024 |doi-access=free}}> [78] => [79] => Another major drawback is finding the right species to perform bioremediation. In order to prevent the introduction and spreading of an invasive species to the ecosystem, an indigenous species is needed. As well as a species plentiful enough to clean the whole site without exhausting the population. Finally the species should be resilient enough to withstand the environmental conditions.{{cite journal | vauthors = Nie J, Sun Y, Zhou Y, Kumar M, Usman M, Li J, Shao J, Wang L, Tsang DC | title = Bioremediation of water containing pesticides by microalgae: Mechanisms, methods, and prospects for future research | journal = The Science of the Total Environment | volume = 707 | pages = 136080 | date = March 2020 | pmid = 31869621 | doi = 10.1016/j.scitotenv.2019.136080 | bibcode = 2020ScTEn.707m6080N }} These specific criteria may make it difficult to perform bioremediation on a contaminated site. [80] => [81] => In agricultural industries, the use of [[pesticide]]s is a top factor in direct soil contamination and runoff water contamination. The limitation or remediation of pesticides is the low bioavailability.{{Cite journal| vauthors = Odukkathil G, Vasudevan N |date=2013|title=Toxicity and bioremediation of pesticides in agricultural soil |journal=Reviews in Environmental Science and Bio/Technology|language=en|volume=12|issue=4|pages=421–444|doi=10.1007/s11157-013-9320-4|bibcode=2013RESBT..12..421O |s2cid=85173331|issn=1569-1705}} Altering the pH and temperature of the contaminated soil is a resolution to increase bioavailability which, in turn, increased degradation of harmful compounds. [82] => [83] => The compound [[acrylonitrile]] is commonly produced in industrial setting but adversely contaminates soils. Microorganisms containing nitrile hydratases (NHase) degraded harmful acrylonitrile compounds into non-polluting substances.{{cite journal | vauthors = Supreetha K, Rao SN, Srividya D, Anil HS, Kiran S | title = Advances in cloning, structural and bioremediation aspects of nitrile hydratases | journal = Molecular Biology Reports | volume = 46 | issue = 4 | pages = 4661–4673 | date = August 2019 | pmid = 31201677 | doi = 10.1007/s11033-019-04811-w | s2cid = 189819253 }} [84] => [85] => Since the experience with harmful contaminants are limited, laboratory practices are required to evaluate effectiveness, treatment designs, and estimate treatment times. Bioremediation processes may take several months to several years depending on the size of the contaminated area.{{cite web | publisher = National Service Center for Environmental Publications | date = 2012 | title = A Citizen's Guide to Bioremediation. | url = https://www.epa.gov/sites/production/files/2015-04/documents/a_citizens_guide_to_bioremediation.pdf | author = United States Environmental Protection Agency }} [86] => [87] => == Genetic engineering == [88] => The use of [[genetic engineering]] to create organisms specifically designed for bioremediation is under preliminary research.{{cite journal | vauthors = Lovley DR | title = Cleaning up with genomics: applying molecular biology to bioremediation | journal = Nature Reviews. Microbiology | volume = 1 | issue = 1 | pages = 35–44 | date = October 2003 | pmid = 15040178 | doi = 10.1038/nrmicro731 | s2cid = 40604152 }} Two category of genes can be inserted in the organism: degradative genes, which encode proteins required for the degradation of pollutants, and reporter genes, which encode proteins able to monitor pollution levels.{{cite book |doi=10.1002/9783527620999.ch21m |chapter=Genetically Engineered Microorganisms and Bioremediation |title=Biotechnology Set |pages=441–63 |year=2001 | vauthors = Menn FM, Easter JP, Sayler GS |isbn=978-3-527-62099-9 }} Numerous members of ''[[Pseudomonas]]'' have been modified with the ''lux'' gene for the detection of the polyaromatic hydrocarbon naphthalene. A field test for the release of the modified organism has been successful on a moderately large scale.{{cite journal |doi=10.1021/es9908319 |title=Controlled Field Release of a Bioluminescent Genetically Engineered Microorganism for Bioremediation Process Monitoring and Control |journal=Environmental Science & Technology |volume=34 |issue=5 |pages=846–53 |year=2000 | vauthors = Ripp S, Nivens DE, Ahn Y, Werner C, Jarrell J, Easter JP, Cox CD, Burlage RS, Sayler GS |bibcode=2000EnST...34..846R }} [89] => [90] => There are concerns surrounding release and containment of genetically modified organisms into the environment due to the potential of horizontal gene transfer.{{cite journal | vauthors = Davison J | title = Risk mitigation of genetically modified bacteria and plants designed for bioremediation | journal = Journal of Industrial Microbiology & Biotechnology | volume = 32 | issue = 11–12 | pages = 639–50 | date = December 2005 | pmid = 15973534 | doi = 10.1007/s10295-005-0242-1 | s2cid = 7986980 }} Genetically modified organisms are classified and controlled under the [[Toxic Substances Control Act of 1976]] under [[United States Environmental Protection Agency]].{{cite journal | vauthors = Sayler GS, Ripp S | title = Field applications of genetically engineered microorganisms for bioremediation processes | journal = Current Opinion in Biotechnology | volume = 11 | issue = 3 | pages = 286–9 | date = June 2000 | pmid = 10851144 | doi = 10.1016/S0958-1669(00)00097-5 }} Measures have been created to address these concerns. Organisms can be modified such that they can only survive and grow under specific sets of environmental conditions. In addition, the tracking of modified organisms can be made easier with the insertion of [[bioluminescence]] genes for visual identification.{{cite book | vauthors = Shanker R, Purohit HJ, Khanna P |year=1998 |chapter=Bioremediation for Hazardous Waste Management: The Indian Scenario |pages=81–96 |chapter-url={{Google books|oLNtgk_VKXsC|page=81|plainurl=yes}} | veditors = Irvine RL, Sikdar SK |title=Bioremediation Technologies: Principles and Practice |isbn=978-1-56676-561-9 }} [91] => [92] => Genetically modified organisms have been created to [[Oil spill#Cleanup and recovery|treat oil spills]] and break down certain [[plastic]]s (PET).{{cite web | vauthors = Bojar D | date = May 7, 2018 | url = https://phys.org/news/2018-05-circular-bioeconomy-synthetic-biology.html | title = Building a circular economy with synthetic biology | work = Phys.org }} [93] => [94] => == Additive manufacturing == [95] => [[Additive manufacturing]] technologies such as [[3D bioprinting|bioprinting]] offer distinctive benefits that can be leveraged in bioremediation to develop structures with characteristics tailored to biological systems and environmental cleanup needs, and even though the adoption of this technology in bioremediation is in its early stages, the area is seeing massive growth.{{cite journal | vauthors = Finny AS | title = 3D bioprinting in bioremediation: a comprehensive review of principles, applications, and future directions | journal = PeerJ | volume = 12 | pages = e16897 | date = February 8, 2024 | pmid = 38344299 | pmc = 10859081 | doi = 10.7717/peerj.16897 | s2cid = 267586847 | doi-access = free }} [96] => [97] => == See also == [98] => {{Portal|Biology|Technology|Fungi}} [99] => {{Div col}} [100] => * [[Bioremediation of radioactive waste]] [101] => * [[Biosurfactant]] [102] => * [[Chelation]] [103] => * [[Dutch pollutant standards]] [104] => * [[Folkewall]] [105] => * [[In situ chemical oxidation]] [106] => * [[In situ chemical reduction]] [107] => * [[List of environment topics]] [108] => * [[Mega Borg Oil Spill|''Mega Borg'' Oil Spill]] [109] => * [[Microbial biodegradation]] [110] => * [[Mycoremediation]] [111] => * [[Mycorrhizal bioremediation]] [112] => * [[Pleurotus]] [113] => * [[Phytoremediation]] [114] => * ''[[Pseudomonas putida]]'' (used for degrading oil) [115] => * [[Restoration ecology]] [116] => * [[Xenocatabolism]]{{div col end}} [117] => [118] => == References == [119] => {{reflist|32em}} [120] => [121] => == External links == [122] => * [https://web.archive.org/web/20100914030753/http://www.mobot.org/jwcross/phytoremediation/ Phytoremediation, hosted by the Missouri Botanical Garden] [123] => * [https://atlasofscience.org/to-remediate-or-to-not-remediate/#more-17692 To remediate or to not remediate?] [124] => * Anaerobic [http://enviro.wiki/index.php?title=Bioremediation_-_Anaerobic Bioremediation] [125] => [126] => {{Clear}} [127] => {{Pollution}} [128] => [129] => {{Authority control}} [130] => [131] => [[Category:Bioremediation| ]] [132] => [[Category:Biotechnology]] [133] => [[Category:Environmental soil science]] [134] => [[Category:Environmental engineering]] [135] => [[Category:Environmental terminology]] [136] => [[Category:Conservation projects]] [137] => [[Category:Ecological restoration]] [138] => [[Category:Soil contamination]] [139] => [[Category:Radioactive waste]] [] => )
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Bioremediation

Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi in mycoremediation, and plants in phytoremediation), living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc. , in natural or artificial settings.

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