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Bioremediation Technologies*Phytoremediation.*Bioaugmentation.*Biostimulation.*Bioreactors.*Land-based Treatments.*Fungal Remediation.
Remediation : Mean clean or stopping of damage to the environment .& Bioremediation :means the treatment of contaminats or waste by using microorganisms such as bacteria to clean them up and become less hazardous to human
They run in to two catigories forms techniques:-
*In situ treatment :bioventing*In situ biodegradation*Bio stimulation*Bio augmentation*Natural attention*Ex situ treatment : 1*Land form 2*Composting 3*Bioreactor
1.Phytoremediation ( in soil and groundwater)use of plants to
Remediation also occurs when bacteria on the roots of the plant degrade the contamination, The plant tissue, which is rich in accumulated contaminants, can be harvested and safely processed.
remove the contaminatsdegradation of contaminants to a less toxic form.
Types of Phytoremediation: A * Phyto extraction B * Phytostabilization C * Phytostimulation D * Phytotransformation
a) Phytoextraction:concentrate the contaminants in aboveground plant tissue ApplicabilityPhytoextraction was primarily employed to recover heavy metals from soils. Limitations - It is limited to shallow soil depths of up to 24 inches. Cost : $60,000 to $100,000 per acre.This includes maintenance, monitoring, verification testing, and $10,000 per acre for planting.
Impact soilSoil beginningremedationcontaminantcontaminanttaken up into plant tissue
b)Phytostabilization involves the reduction of the mobility of heavy metals in soil. The mobility of contaminants is reduced by the accumulation of contaminants by plant rootsLimitationseffective at depths of up to 24 inches
Applicability to remediate large-scale areas having low contamination are not feasible. Field work has shown that phytostabilization is efficient at lowering levels of Pb in a sand.
Studies also suggest that phytostabilization may reduce metal leaching by converting metals from a soluble oxidation state to an insoluble oxidation state. Plants have reduced available and toxic Cr(VI) to unavailable and less toxic Cr(III) .
Cost: cost efficient method when compared to other technologies.
Exudates(Enzymes,Alcohol,Phenols,Carbohydrates& acids)Precipitation in soilReduceSurfaceerosionContaminant plume mycorrhizoPhytostabilization
c)Phytostimulation: is the breakdown of organic contaminants in the soil via microbial activity in the plant root zone.
Microbial activity is stimulated in several ways: (1) sugars, carbohydrates, amino acids, acetates, and enzymes (2) root systems bring oxygen Limitations levels of contamination in shallow areas.
Cost:more cost effective than many other technologies. phytostimulation ranges from $10 to $35 per ton of soil. Other technologies, such as incineration, range from $200 to $1,000 per ton of soi
dehalogenase Oophosphotase O peroxidase O OnitroredutaseOnitrilaseherbicidesPSPS,PCBsChlorinatedsolventd)Phytotransformation,is the breakdown of organic contaminants Direct uptake of chemicals into Plant tissue.Limitations Soil must be less than 3 ft in depthContaminants may still enter the food chain through animals or insects that eat plant material
Applicability to remove contaminants from petrochemical sites and storage areas, fuel spills, landfill leachates, and agricultural chemicals .
introduction of genetically engineered strains of microbes to a contaminated site . can be introduced to successfully degrade specific waste compounds.Biodegradation refers to the degradation of organic contaminants in soil by indigenous or transplanted microorganisms, primarily bacteria and fungi.
LimitationsCertain characteristics in the soil matrix preferential
may result inpoor contact between microbes and contaminants.
flow paths of injected fluids
Biostimulation:Biostimulation refers to the addition of oxygen and/or inorganic nutrients to indigenous microbial populations in soils.In situor ex situmethods can be employed to stimulate biodegradation of contaminants.*Bioventing*
Bioventing is a process of stimulating the natural in situ biodegradation of contaminants in soil by providing
Applicability Bioventing is applicable to any chemical that can be aerobically biodegraded. Techniques have been successfully used to remediate soils contaminated by petroleum hydrocarbons, non-chlorinated solvents, some pesticides, wood preservativesLimitations Factors that may limit the applicability and effectiveness of the process include:(1) low permeability soils (reduce bioventing performance); (2) monitoring of off-gases at the soil surface may be required;(3) low soil moisture content, which may be caused by bioventing, limits biodegradation .air oxygen
to existing soil microorganisms
microbial activityto sustain
Two basic criteria have to be satisfied for successful bioventing: 1- air must be able to pass through the soil in sufficient quantities to maintain aerobic conditions. 2- microorganisms must be present in concentrations large enough to obtain reasonable biodegradation rates. Cost:ranges from $10 to $60 per cubic yard. At sites with over 10,000 cubic yards of contaminated soilBioreactors:rhighly controlled methods of treating contaminated soils. Because temperature, pH, nutrient levelscan be controlled in constructed batch- or continuously-fed reactors, microbial activity, and thus contaminant degradation,it can be optimized in:*Slurry-based reactors.
Slurry-phase biological treatment is performed in a reactor to remediate a mixture of water and excavated soil.
The soil is suspended in a reactor vessel and mixed with nutrients and oxygen. Microorganisms, acid, or alkali may be added depending on treatment requirements.
used to remediate soils contaminated by hydrocarbons, petrochemicals, solvents, pesticides and other organic chemicals. Bioreactors are more suitable for soils with low permeabilityLimitations treatment can be expensive
When biodegradation is complete
the soil slurry is dewatered
*Fungal Remediation:use of fungi to remediate organic soil contaminants, primarily hydrocarbons. Remediation of soil using white-rot fungus has been tested in both in situ and reactor-based systems.LimitationsA major limitation of white-rot fungus is its sensitivity to biological process operations. It has been observed that the fungus does not grow well in suspended cell systems, enzyme induction is negatively affected by mixing action; and the ability of the fungus to effectively attach itself to fixed media is poorCost$75 per cubic yard of contaminated soil .
Applicability&Cost.Cunningham, S.D., J.R. Shann, D.E. Crowley, and T.A. Anderson, 1997, Phytoremediation of Contaminated Soil and Water, in Phytoremediation of Soil and Water Contaminants, E.L. Kruger, T.A. Anderson, and J.R. Coats, Eds., ACS Symposium Series 664, American Chemical Society, Washington, DC.2.Schnoor, J.L., 1997, Phytoremediation, Technology Overview Report, Ground-Water Remediation Technologies Analysis Center, Series E, Vol. 1, October.Limitations3.Huang, J.W, J. Chen, and S.D. Cunningham, 1997,Phytoextraction of Lead from Contaminated Soils, in Phytoremediation of Soil and Water Contaminants, E.L. Kruger, T.A. Anderson, and J.R. Coats, Eds., ACS Symposium Series 664, American Chemical Society, Washington, DC.*PhytostabilizationApplicability1.Blaylock, M., B. Ensley, D. Salt, N. Kumar, V. Dushenkov, and I. Raskin, 1995, Phytoremediation: A Novel Strategy for the Removal of Toxic Metals from the Environment Using Plants,Biotechnology, 13 (7), pp.468-474.2.Miller, R., 1996, Phytoremediation, Technology Overview Report, Ground-Water Remediation Technologies Analysis Center, Series O, Vol. 3, October.Cost3.Schnoor, J.L., 1997, Phytoremediation, Technology Overview Report, Ground-Water Remediation Technologies Analysis Center, Series E, Vol. 1, October.*PhytostimulationDefinition &Applicability1.Anderson, T.A., E.A. Guthrie, and B.T. Walton, 1993, Bioremediation in the Rhizosphere,Environmental Science and Technology27 (13), pp. 2630-2636.Applicability&cost2.Miller, R., 1996, Phytoremediation, Technology Overview Report, Ground-Water Remediation Technologies Analysis Center, Series O, Vol. 3, October.Limitations3.Schnoor, J.L., 1997, Phytoremediation, Technology Overview Report, Ground-Water Remediation Technologies Analysis Center, Series E, Vol. 1, October
*PhytotransformationDefinition &Applicability&Cost1.EPA, 1998, A Citizen's Guide to Phytoremediation, U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, EPA 542-F-98-011, August.Limitations3.Miller, R., 1996, Phytoremediation, Technology Overview Report, Ground-Water Remediatoin Technologies Analysis Center, Series O, Vol. 3, October.*Biodegradation 1Kumar, R. and C.B. Sharma, 1992, Biodegradation of Carbamate Pesticide Propoxur in Soil, inEnvironment and Biodegradation, V.P. Agrawal and S.V.S. RanaIndia eds., Society of Biosciences, India, pp. 137-148.2.Ward, F.P., Military Applications of Biodegradation, inBiotechnology and Biodegradation, Advances in Applied Biotechnology Series, Vol. 4, A. Chakrabarty, D. Kamely, and G. Omenn eds., Gulf Publishing, Houston, TX, pp. 147-154.*BiostimulationBioventingDefinition &Applicability1.U.S. Air Force Environics Directorate of