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Bioremediation ppt FINAL 005.pptx
- 2. • Soil health • Sources of soil contamination • Bioremediation • Principles • Components • Classification • Mechanisms 2
- 3. Contd… • Phytoremediation • Advantages of bioremediation • Limitations of bioremediation • Future strategies and challenges • Conclusion 3
- 4. • Vital living system • Sustain plant productivity and animal health • Improve water and air quality 4
- 5. Sources of soil contamination 1. Natural sources 2. Anthropogenic sources 5
- 6. Natural sources • Volcanoes • Tsunami waves • Storms in desert areas etc. 6
- 7. Anthropogenic sources • Agricultural practices • Industrial wastes • Disposal of solid wastes on land • Mining activities • Heavy metal pollutants • Radioactive pollutants 7
- 8. Sources… 8
- 10. Types of pollutants 10 Organic Inorganic (Rao et al., 2010) Fuel hydrocarbons, polynuclear aromatic hydrocarbons ( PAHs ), polychlorinated biphenyls ( PCBs ), chlorinated aromatic compounds, detergents, and pesticides Nitrates, phosphates, heavy metals (cadmium, chromium and lead); inorganic acids & radionuclides (radioactive substances)
- 11. Ill effects of organic contaminants 11 DDT effect
- 12. Heavy metals • Metals and metalloids - specific gravity >5 g cm-3 (Nriagu and Pacyna 1988; Hawkes 1997) Toxicity hazards • Mercury - Minamata • Mercury in infants - Acrodynia • Cadmium - Itai - itai • Arsenic - Black foot • Silver - Argyria 12
- 13. 13 Itai – itai (Cd) Diseases
- 14. 14 Black foot - As Argyria - Ag
- 15. 15 Physical remediation Chemical remediation Soil flushing Incineration Cement kiln Air stripping Thermal desorption Solvent extraction Oxidation reduction Precipitation Neutralization Encapsulation SOIL REMEDIATION METHODS Bioremediation (Ward and Singh, 2004)
- 16. Bioremediation is a “treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non toxic substances”. (United States EPA) 16 Bioremediation???
- 17. Principles of Bioremediation Degradation Sequestration Removal 17 (Anushree Malik, 2006)
- 18. 18 (Fulekar, 2010) Electron donor Organic contaminant degradation Oxidised electron donor Degradation
- 19. Trapping of pollutants Conversion to nontoxic forms Unavailable to the biological systems Sequestration 19
- 20. Removal Physical removal of pollutants by microbes Unavailable to the biological systems 20
- 22. Types of Bioremediation 22 Bacteria Bacterial bioremediation Fungi Mycoremediation Algae Phycoremediation Plants Phytoremediation Biomolecules derived from micro organisms Derivative bioremediation Rhizosphere Rhizoremediation Nanoparticle Nanoremediation
- 23. Classification of Bioremediation A. In situ bioremediation - Treating the contaminated materials at the site B. Ex situ bioremediation Material to be bioremediated is moved to another site to be treated 23
- 24. In situ bioremediation Types • Bioventing • Biostimulation • Biosparging • Bioaugmentation • Bioslurping 24
- 25. • Induces air or oxygen flow into the unsaturated zone • Activity of indigenous bacteria is enhanced (Rockne and Reddy, 2003) 25 1) Bioventing
- 26. Bioventing 26 Oxygen release compound Direct oxygen method
- 27. 2) Biostimulation • Modification of microbial environment • Addition of limiting nutrients and electron acceptors (Rhykerd et al., 1999) 27
- 28. Effect of carbon substrate on perchlorate contaminated soil 28 (Sarat and Kenneth, 2016) Application of inexpensive carbon substrates – chicken litter - remediation of perchlorate contaminated soil
- 29. 3) Biosparging • Injection of pressurised air below the water table • Increases mixing in the saturated zone (Vidali, 2001) 29
- 30. Biosparging 30 Injection of pressurised air below the water table
- 31. 4) Bioaugmentation Addition of pollutant degrading microorganisms to augment the biodegradative capacity of indigenous microbial populations. 31
- 32. Contd… • Adding microbial consortia to contaminated soil - Phanerochaete chrysosporium, Cunninghamella sp., Alternaria alternate ( fr. ) Keissler Penicillium chrysogenum Aspergillus niger, Bacillus sp., Zoogloea sp. & Flavobacterium enhanced the degradation rate significantly (41.3%) (Li et al., 2009) 32
- 33. 5) Bioslurping Vacuum extraction of the floating contaminant and water 33
- 35. Mechanism of Slurry phase bioremediation 35
- 36. Solid phase bioremediation 1. Composting • Organic contaminants (eg. PAHs) are converted by microorganisms to safe, stabilized byproducts (Chang and Chen, 2010) 36
- 37. Three ways of composting : Static Pile - Aerated using vacuums or blowers Mechanically Agitated in-vessel composting – Contaminants are put into a treatment tank, turned up and mixed Windrow Composting - Contaminants are laid out in long piles and mixed by a tractor 37
- 38. Composting 38 Static pile Windrow composting In-vessel composting
- 40. Biopiles/ Biocells • Excavated soil mixed with amendments, forced aeration • Volatile contaminants - easily controlled • Converted to CO2 and H2O • Treatment of surface contaminated with petroleum hydrocarbons • Control physical losses of the contaminants by leaching and volatilization (EPA, 2003) 40
- 41. Biopile 41
- 42. Biofilters • Filters with degrading organisms supported on a high surface area viz. granulated activated carbon or compost 42
- 43. Bioreactors • Biodegradation of contaminants in a large tank or reactor • Used to treat liquid effluents/slurries or contaminated solid waste/soil (Sharma, 2012) 43
- 44. Bioreactor 44
- 45. Mechanism of salt removal by bioremediation 45
- 46. Mechanisms in bioremediation in the case of dead and living biomass Microorganisms Microalgae, bacteria, fungi, yeast Biosorption mechanism Passive processes Dead and living biomass Bioaccumulation mechanism Active processes Living biomass 46
- 47. How does bioremediation work? Final waste- CO₂ & H2O Food (contaminant) O2 , other nutrients Enzymes 47
- 48. In case of oil… 48
- 49. Mycoremediation • Fungi (eg. Aspergillus and Penicillium) and yeasts (eg. S. cerevisiae) - remove heavy metals – Cd & As (Bhakta et al., 2014) 49
- 50. Bacterial remediation • Deinococcus geothermalis - radioactive waste at high temperatures • Acenitobacter baumanii - crude oil (Paul et al., 2005) Pseudomonas fluorescens HK44 - naphthalene (Wasilkowski et al.,2012) Pseudomonas aeruginosa (NRRL B-5472), P. putida (NRRL B-5473) - naphthalene, salicylate and camphor 50
- 51. Contd… • Geobacter metallireducens - uranium in mining operations (Kumar et al., 2011) • Escherichia coli, Bacillus subtilis, Saccharomyces boulardii, Enterococcus faecium and Staphylococcus aureus - removal of heavy metals from water bodies (Min-sheng et al.,2001) 51
- 53. Phycoremediation • Biosorption of Cd2+ by a capsulated nuisance cyanobacterium - Microcystis • Naturally occurring cells showed higher efficiency for biosorption of Cd2+ and Ni2+ as compared to lab cultured cells (Rai et al., 1998) 53
- 54. Pollutant Microorganism(s) Reference Atrazine Acinetobacter sp. Singh et al., 2004 Pseudomonas sp. strain ADP Shapir and Mandelbaum, 1997 Chlorpyrifos Aspergillus niger Trichoderma viride Mukherjee and Gopal, 1996 Bacterium strain B-14 Singh et al., 2004 2,4,6-Trichlorophenol Alcaligenes eutrophus TCP Andreoni et al., 2003 2,4-Dichlorophenoxyacetic acid Ralstonia eutropha (pJP4) Daane and Häggblom, 1999 Ralstonia eutropha JMP134 Roane et al., 2001 Carbon tetrachloride Pseudomonas stutzeri KC Dybas et al., 2002 BTEX B. sp. Strain JS150 Kahng et al.,( 2001) Bacillus cepacia G4 Shields et al.,( 1995) Ralstonia pickettii PKO1 Byrne et al., (1995) Sphingomonas yanoikuyae B1 Kim and Zylstra, (1999) Orange 3, 4- (4nitrophenylazo) aniline Pleurotus ostreatus Zhao et.al.,(2006) 54 Microorganisms involved in bioremediation
- 55. 55 Hydrolases Phosphotriesterases, amidases, proteases Dehalogenases Cellulases and amylases Transferases Glutathione transferases Oxidoreductases Oxygenases, peroxidases Enzymes in Bioremediation (Whiteley and Lee, 2006)
- 56. Phytoremediation • Direct use of living green plants for in situ removal, degradation, or containment of contaminants in soils, sludges, sediments, surface water and groundwater 56
- 58. Strategies involved in phytoremediation 58
- 59. Types of plants used: 59
- 60. Contd… 60 Helianthus annuus Eicchornia crassipes Brassica juncea
- 62. Hyper accumulators in phytoremediation Thlaspi caerulescens - Alpine pennygrass 62 (Negri, 1996) Pennywort Duckweed
- 63. Phytostabilisation • Immobilisation of contaminants in the soil through absorption and accumulation by roots and precipitation within the root zone • Rhizodegradation or plant assisted bioremediation 63
- 64. Phytostabilization of mercury by willow roots 64 (Wang, 2004)
- 65. Phytotransformation • Phytodegradation • Breakdown of contaminants within the plant 65 (Subramanian, 2006)
- 66. Phytostimulation • Breakdown of contaminants within the root 66
- 67. Phytovolatilisation • Contaminants volatile forms and transpires them into the atmosphere • Mercury and selenium 67
- 68. Rhizofiltration • Adsorption or precipitation into plant roots • Used to address ground water rather than soil 68
- 69. Rhizofiltration contd… 69 Source: http://systemsbiology.usm.edu/BrachyWRKY/WRKY/Rhizofiltration.html
- 70. Contd… • Phytoremediation of heavy metals viz. Cd, Pb, Cu and Zn by Trifolium alexandrinum (Ali et al., 2012) • Ryegrass and fescue - PAH contaminated soils due to their fibrous root systems with extensive surface area for microbial colonisation (Binet et al., 2000) 70
- 71. Types of phytoremediation techniques Process Pollutant Medium Plants Phytoextraction Cd, Pb, Zn, As, Petroleum, Hydrocarbons and Radionuclides Soil & Groundwater Viola baoshanensis, Sedum alfredii, Rumex crispus Phytotranformation xenobiotic substances Soil Cannas Phytodegradation DDT, Expolsives, waste and Nitrates Groundwater Elodea Canadensis, Pueraria Rhizofiltration Zn, Pb, Cd, As Groundwater Brassica juncea, Phytostabilization (Immobilization) Cu, Cd, Cr, Ni, Pb, Zn Soil Anthyllis vulneraria, Festuca arvernensis 71 (Macek, 2000)
- 72. Extraction of heavy metals – plant 72
- 74. Bioremediation by Nano-particles • Massive surface area and unique properties of nanoparticles - application to environmental remediation • Use of nanoparticles in bioremediation is also called Nanoremediation • Nanoparticles either act as carrier for microorganisms or directly act in remediation 74
- 75. Advantages of bioremediation • Minimal exposure of onsite workers • Long term protection of public health • Safe method • Cheap method • Ecofriendly • Natural process 75
- 76. Limitations of bioremediation • Doesn’t suit all situations • Time consuming • Cannot degrade all hazardous wastes • No acceptable endpoints for bioremediation treatments • Barriers to commercialization of bioremediation 76
- 77. Future strategies and challenges for bioremediation • Recovering valuable metals • Bioremediation of Radioactive Wastes • Genetically engineered microbes will require further study to clarify issues of safety. • The construction of environmentally robust micro organism 77
- 78. 78 • Bioremediation technology - relies not only on pollutant interaction with a particular (micro)organism but also on the bioavailability of the environmental conditions
- 79. Conclusion… • Emerging as a viable, eco-friendly, cost effective and aesthetically pleasing technique for the remediation of contaminated soils • Bioremediation – for sustainable soil health • Tool for rejuvenation of degraded lands 79
- 80. 80
- 81. 81
- 82. 82
Editor's Notes
- Soil health is the capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health
- : http://www.pollutionissues.com/Re-Sy/Soil-Pollution.html#ixzz4QnXoxQIm Read more: http://www.pollutionissues.com/Re-Sy/Soil-Pollution.html#ixzz4QnY5b730
- Metals and metalloids - specific gravity >5 g cm-3, or 5 times or more greater than water
- "Remediate" means to solve a problem, and "bio-remediate" means to use biological organisms to solve an environmental problem such as contaminated soil or groundwater by breaking down hazardous substances into less toxic or non toxic substances”.
- degradation, sequestration, or removal of the toxic pollutants as the result of microbial activity.
- The pollutants is trapped or changed in a way that makes it nontoxic or unavailable to the biological systems.
- means that while the pollutant is not necessarily degraded, the microbes physically remove it from the soil or water so that it can be collected and disposed of safely.
- Component of bioremediation- Bioremediation triangle Bioremediation require three basic components by which whole process can be operative. These components are: a) microorganism, b) substrate (pollutants) c) environment. Advanced technologies based on either optimizing these components or by improving interaction between them. Bioremediation triangle Microorganisms, Fungi, algae etc. Substrate (pollutants) Environment 168 The interaction of microorganism component with environment defines the time taken to proliferate the microorganism in particular environment (type of soil, temperature, pH, the presence of oxygen or other electron acceptors, and nutrients) while interaction between the substrate and environment defines the affinity of pollutant towards soil and water. The substrate and microorganism interaction is important for the time requires neutralizing the hazardous compound. Thus the three component and there interaction is important for optimization of bioremediation process. The current advance methods are utilizing these above interaction for formulating new consortia and their application. Some of recent advance techniques are discussed here which are used in agriculture and there near future applications. Technique
- Classification of Bioremediation strategies according to the biomediator involved.
- nature of contaminants
- (1) Bioventing An in situ remediation technology that uses microorganisms to biodegrade organic constituents adsorbed on soils in the unsaturated zone. enhances the activity of indigenous bacteria and simulates the natural in situ biodegradation of hydrocarbons in soil by inducing air or oxygen flow into the unsaturated zone and, if necessary, by adding nutrients. During bioventing, oxygen may be supplied through direct air injection into residual contamination in soil. Bioventing primarily assists in the degradation of adsorbed fuel residuals, but also assists in the degradation of volatile organic compounds (VOCs) as vapors move slowly through biologically active soil. [[[[[[[Application of Bioremediation on Solid Waste Management: A Review Tiwari Garima* and Singh SP ]]]]]]]]] (Rockne K and Reddy K, 2003)
- Oxygen release compound
- Addition of various forms of limiting nutrients and electron acceptors, such as phosphorus, nitrogen, oxygen, or carbon (eg. in the form of molasses), which are otherwise available in quantities low enough to constrain microbial activity Challenge - Delivery of additives to be readily available to subsurface microorganisms is based on the local geology of the subsurface.
- The results suggest that application of inexpensive carbon substrates such as chicken litter without the need for addition of chemical fertilizers may be a feasible remediation strategy in perchlorate contaminated soils with large active, native microbial populations. Sarat Kannepalli*, Kenneth W. Farrish
- Bioremediation an overview{2} Biosparging. Biosparging involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria. Biosparging increases the mixing in the saturated zone and thereby increases the contact between soil and groundwater. The ease and low cost of installing small-diameter air injection points allows considerable flexibility in the design and construction of the system. {{{bioremed review article}}}
- Used for petroleum constituents that are dissolved in groundwater, adsorbed to soil below the water table and within the capillary fringe
- Sometimes microorganisms from the remediation site are collected, separately cultured, and returned to the site as a means of rapidly increasing the microorganism population at the site. Usually an attempt is made to isolate and accelerate the growth of the population of natural microorganisms that preferentially feed on the contaminants at the site. It is commonly used in municipal wastewater treatment to restart activated sludge bioreactors
- Bioslurping Bioslurping combines elements of bioventing and vacuum-enhanced pumping of free-product that is lighter than water (light non-aqueous phase liquid or LNAPL) to recover free-product from the groundwater and soil, and to bioremediate soils. The bioslurper system uses a “slurp” tube that extends into the free-product layer. Much like a straw in a glass draws liquid, the pump draws liquid (including free-product) and soil gas up the tube in the same process stream. Pumping lifts LNAPLs, such as oil, off the top of the water table and from the capillary fringe (i.e., an area just above the saturated zone, where water is held in place by capillary forces). The LNAPL is brought to the surface, where it is separated from water and air. The biological processes in the term “bioslurping” refer to aerobic biological degradation of the hydrocarbons when air is introduced into the unsaturated zone.[5] LNAPL refers to Light Non-Aqueous Phase Liquids (those that are lighter than water, generally petroleum hydrocarbon liquids Bioslurping is performed using a tube positioned in a well so the end of the tube is near the water-table level in the formation. Vacuum is applied to the well using a single aboveground vacuum pump, and LNAPL and groundwater are removed from the well by air entrainment. The depth of the tube can be adjusted manually, if needed. The negative pressure established in the well depends on the air withdrawal rate and the permeability of the surrounding formation. The reference to biological processes in the term “bioslurping” results from the possibility that aerobic biological degradation of the hydrocarbons will be enhanced as a result of the introduction of air into the unsaturated zone. Slurping is used as the term to describe the air entrainment and aerodynamic dragging action that lifts fluids up the slurping tube. The bioslurper system pulls a vacuum of up to 20 in. Hg on the recovery well to create a pressure gradient to force movement of LNAPL into the well. The system is operated to cause very little drawdown of the water-table level, thus reducing the problem of free-product entrapment in soils when pumping is ceased. Aeration of the unsaturated zone soils is achieved by withdrawing soil gas from the recovery well. The slurping action of the bioslurper system cycles between recovering liquid (free product and/or groundwater) and soil gas. The rate of soil-gas extraction is dependent on the recovery rate of liquid into the well. When free-product removal activities are complete, the bioslurper system can be converted to a conventional bioventing system to complete remediation of the unsaturated zone soils. A significant feature of the bioslurping process is the induced airflow, which in turn induces LNAPL flow toward the well. The pressure gradient created in the air phase results in a driving force on the LNAPL that can be significantly greater than the driving force that can be induced by pumping the LNAPL with no airflow. Also of importance is the fact that the vacuum extraction mechanism pulls LNAPL along more permeable horizontal zones. In addition, the continuity of the LNAPL phase is better maintained by eliminating the cone of depression formed during drawdown recovery, thus increasing the relative permeability for LNAPL. For these reasons, bioslurping has the potential for removing more LNAPL and at greater rates than do other pumping mechanisms. Vacuum extraction of the floating contaminant and water from the unsaturated zone
- Typically, thermophilic conditions (54 to 65°C) must be maintained to properly compost soil contaminated with hazardous organic contaminants and in most cases, this is achieved by the use of indigenous microorganisms. There are different types of bulking agents used in the composting such as wood chips, saw dust, grass hay, wheat straw, corn stalks, grass clippings, rabbit manure, fruit and vegetable waste, garden trimmings, horse manure, deciduous leaves, cow dung, etc [3,4]. These bulking agents are use in the composting process according to need of the compost, such as nutritive value, moisture, pH and air supply to compost material. Different bulking agents used in different composting process such as food waste composting, vermicomposting, composting of industrial waste, agricultural waste composting and composting of weeds, etc [5-7]. It has been shown in a study that the bulking agents like rice husk, sawdust and rice bran increased the degradation and resulted a very good quality compost of food waste [1].
- Aerated Static Pile (ASP) composting, refers to any of a number of systems used to biodegrade organic material without physical manipulation during primary composting. The blended admixture is usually placed on perforated piping, providing air circulation for controlled aeration . It may be in windrows, open or covered, or in closed containers. With regard to complexity and cost, aerated systems are most commonly used by larger, professionally managed composting facilities, although the technique may range from very small, simple systems to very large, capital intensive, industrial installations.[1] Aerated static piles offer process control for rapid biodegradation, and work well for facilities processing wet materials and large volumes of feedstocks. ASP facilities can be under roof or outdoor windrow composting operations, or totally enclosed in-vessel composting, sometimes referred to tunnel composting.[2]
- Is a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded. The goal is to stimulate indigenous biodegradative microorganisms and facilitate their aerobic degradation of contaminants. In general, the practice is limited to the treatment of superficial 10–35 cm of soil. Since landfarming has the potential to reduce monitoring and maintenance costs, as well as clean-up liabilities, it has received much attention as a disposal alternative. Composting Is a technique that involves combining contaminated soil with nonhazardous organic amendants such as manure or agricultural wastes. The presence of these organic materials supports the development of a rich microbial population and elevated temperature characteristic of composting. Solid phase treatment system for contaminated soil where tilling and soil amendment techniques are used to encourage the growth of beneficial microorganisms in contaminated area. Solid phase treatment system for contaminated soil where tilling and soil amendment techniques are used to encourage the growth of beneficial microorganisms in contaminated area.
- Biopile treatment is a full-scale technology in which excavated soils are mixed with soil amendments, placed on a treatment area, and bioremediated using forced aeration. The contaminants are reduced to carbon dioxide and water. The basic biopile system includes a treatment bed, an aeration system, an irrigation/nutrient system and a leach ate collection system. Moisture, heat, nutrients, oxygen, and pH are controlled to enhance biodegradation. The irrigation/nutrient system is buried under the soil to pass air and nutrients either by vacuum or positive pressure. Soil piles can be up to 20 feet high and may be covered with plastic to control runoff, evaporation and volatilization, and to promote solar heating. If volatile organic compounds (VOCs) in the soil volatilize into the air stream, the air leaving the soil may be treated to remove or destroy the VOCs before they are discharged into the atmosphere. Treatment time is typically 3 to 6 months [7] 1 Also known as biocells Piles of soil are placed over top of a big vacuum pump. The vacuum pump pulls air through the pile of soil to allow oxygen to get through the soil to the micro organisms. Contaminants which may be turned into gas forms are easily controlled as they are simply sucked with the air stream through the soil.
- A slurry bioreactor may be defined as a containment vessel and apparatus used to create a three-phase (solid, liquid, and gas) mixing condition to increase the bioremediation rate of soil- bound and water-soluble pollutants as a water slurry of the contaminated soil and biomass (usually indigenous microorganisms) capable of degrading target contaminants.
- Microorganisms employed in the bioremediation and processes/mechanisms involved in the case of dead and living biomass Bioremediation can be separated into two categories, biosorption and bioaccumulation. Biosorption is a passive adsorption mechanism that is fast and reversible [6, 49]. The metals are retained by means of physicochemical interaction (e.g., ion exchange, adsorption, complexation, precipitation, and crystallization) between the metal and the functional groups present on the cell surface [6, 47–50]. Several factors can affect the biosorption of metals, such as pH, ionic strength, biomass concentration, temperature, particle size, and presence of other ions in the solution [48]. Both living and dead biomass can occur for biosorption because it is independent of cell metabolism. On the other hand, bioaccumulation includes both intra- and extracellular processes where passive uptake plays only a limited and not very well-defined role [6]. Therefore, living biomass can only occur for bioaccumulation.
- Uses naturally occurring microorganisms to break down hazardous substances into less toxic or nontoxic substances
- 43] Bhakta J. N., Munekage Y., Ohnishi K., Jana B. B., Balcazar J. L. Isolation and characterization of cadmium and arsenic-absorbing bacteria for bioremediation. Water, Air, and Soil Pollution 2014; 225 2150–2159. The most advantage of fungi is highly variable, ranging in size from mushrooms to microscopic molds. They are easy to grow and produce a substantial biomass. The cell walls of fungi are rich in polysaccharides and glycoproteins, which contain, for instance, amine, imidazole, phosphate, sulfate, sulfhydryl, and hydroxyl groups [56, 57].
- [45] Paul D., Pandey G., Jain R. K. Suicidal genetically engineered microorganisms for bioremediation: need and perspectives. Bioessays 2005; 27 (5) 563–573. Engineered strains of Deinococcus geothermalis have been developed for the bioremediation of environments containing mixed radioactive waste at high temperatures. Recombinant strain of Acenitobacter baumanii was found to enhance degradation rates at sites contaminated with crude oil.
- [21] Kumar A., Bisht B. S., Joshi V. D., Dhewa T. Review on bioremediation of polluted environment: a management tool. International Journal of Environmental Sciences 2011; 1 (6) 1079–1093. The species Escherichia coli, Bacillus subtilis, Saccharomyces boulardii, Enterococcus faecium, and Staphylococcus aureus have also been used for the removal of heavy metals from water bodies. Geobacter metallireducens - Uranium from drainage waters in mining operations and from contaminated groundwater
- studied biosorption i.e. both adsorption and absorption of Cd++ by a capsulated nuisance cyanobacterium, Microcystis both from field and laboratory. The naturally occurring cells showed higher efficiency for Cd++ and Ni++ as compared to laboratory cells. Rai et al., (1998) Microcystis is a nuisance and bloom-forming cyanobacteria
- Phytoextraction Phytostabilisation Phytotransformation Phytostimulation Phytovolatilisation Rhizofiltration
- How does it works?
- 350 plant species naturally take up toxic materials • Sunflowers - used to remove radioactive cesium and strontium from Chernobyl site • Water hyacinths used to remove arsenic from water supplies in Bangladesh, India
- The uptake of contaminants by plant roots and movement of these contaminants from roots to the above part of the plants by absorbing, concentrating and precipitating the contaminants Works well on metals such as lead, cadmium, copper, nickel etc. Zhuang P, Yang QW, Wang HB, Shu WS, 2007. Phytoextraction of heavy metals by eight plant species in the field.Water, Air and Soil Pollution, 184: 235-242.
- Phyto thesis .pdf
- Mobility of the contaminant is reduced, migration to ground water is prevented and thus bioavailability of the metal in the food chain is reduced.
- Breakdown of contaminants taken up by the plants using metabolic processes within the plant Murali Subramanian, David J. Oliver, and Jacqueline V. Shanks, 2006. TNT Phytotransformation Pathway Characteristics in Arabidopsis: Role of Aromatic Hydroxylamines. Biotechnology Programme, 22: 208 -216.
- Breakdown of contaminants within the root Carried out by rhizospheric microorganisms Works well in removal of petroleum hydrocarbons
- Macek T, Mackova M, Kas J, 2000. Exploitation of plants for the removal of organics in environmental remediation. Biotechnology Advances, 18: 23-34.
- The massive surface area and unique properties of nanoparticles have led to much research on their application to environmental remediation. Use of nanoparticles in bioremediation is sometimes also called Nanoremediation. Nanoparticles are either act as carrier for microorganisms or directly act in remediation
- Less cost for equipment and labor because most of the work is done by the microorganisms
- All hazardous wastes cannot be degraded. Many metals destroy and are highly toxic to microorganisms. Thus no biological degradation can take place. Difficult to extrapolate from pilot-scale studies to field operations
- The construction of environmentally robust micro organism possessing the properties making it suitable for metal remediation remains a future challenge
- Bioremediation could be a cost-effective alternative to physico-chemicaldecontamination methods. Environmentalists and soil scientists have witnessed an increasing understanding of metal interaction with (micro)organisms that resulted in the design of effective processes for heavy metals bioremediation.3. Novel processes stemming from recombinant microorganisms or transgenic plantshave been proposed based on an important understanding of the molecular mechanisms of metal uptake, binding to biopolymers, and detoxification.However, microbial remediation as well as phytoremediation of heavy metals isstill mainly a basic research problem.4. The construction of environmentally robust (micro)organism possessing the properties making it suitable for metal remediation remains a future challenge. Mohamed Rashad 2007 It should also be stressed here, that the practicable of bioremediation technologyrelies not only on metal interaction with a particular (micro)organism but also onthe bioavailability of the environmental conditions allowing growth and survivalof (micro)organisms in polluted areas. Therefore, organisms with the capacity togrow survive and properly function in heavy metals polluted soils are stronglyneeded in both in situ and ex situ bioremediation processes.6. Ex situ heavy metal remediation processes may be performed by adjusting some parameters and by applying “standard protocols” for example, biosorption. On theother hand, the in situ bioremediation of heavy metals pollution seems to be morerestricted by some parameters that are difficult to control such as, climate and soilmatrix and thus processes that are largely independent from such variables need to be rapidly optimized.7. Present policy regulates the release of genetically modified microorganisms intothe environment and limits their use. Consequently, present policy slows downthe program in this research field