Mercury, arsenic, lead, and chromium are often prevalent at contaminated sites. Phytostabilization can occur through the sorption, precipitation, complexation, or metal valence reduction. Bacteria, fungi, yeast and algae can remove heavy metals and radionuclide from aqueous solution in substantial quantities.
For example, several anaerobic strains of bacteria ex. Through studies of bacterial species that thrive in radioactively-contaminated sites, scientists are discovering even more resistant organisms capable of absorbing or detoxifying nuclear wastes.
Persistence of Lead in the Environment Lead is a ubiquitously distributed in nature in biologically inactive form. Bioremediation of Lead by Microorganisms Soil bacteria could directly or indirectly interact with lead present in the contaminated soil and reduced it into non-toxic forms.
Common approaches for providing oxygen above the water table include landfarmingcomposting and bioventing. Potent metal biosorbents under the class of bacteria include the genera of Bacillus, Pseudomonas, Streptomyces and P.
Import into RefWorks 1. There are few plants species known for higher accumulator and show their potential towards the removal of metals from contaminated soils. The plants decrease the amount of Bioremediation manipulating nuclear and heavy metal percolating through the soil matrix, which may act as a barrier and prevent direct contact with the contaminated soil.
In the last decade, it was observed that these pools of radioactive waste were a hotbed for several unique strains of radioactive-resistant bacteria capable of performing remarkable metal chemistry on these radionuclides, including the oxidation or reduction of metallic ions analogous to current waste clean-up strategies.
Bacteria, fungi, yeast and algae can remove heavy metals and radionuclide from aqueous solution in substantial quantities. For endurance under metal-stressed environment, plant growth promoting rhizobacteria have evolved several mechanisms by which they can immobilize, mobilize or transform metals rendering them inactive to tolerate the uptake of heavy metal ions.
Amongst the various microorganisms, fungal biomasses were very effective due to presence of high percentage of cell wall material, which may have the excellent metal binding capacity.
The in-situ process is useful for treating surface or shallow contamination.
Under ideal conditions, the biodegradation rates of the low- to moderate-weight aliphaticalicyclicand aromatic compounds can be very high.
Beside this there are several limiting factors for phytoextraction. The aim of this article is to give an overview of the arsenic and lead contaminant in soil and also the mechanism of removal of these toxic metals from the contaminated sources by the potent application of plants and microbes.
The growth of fern plants was much better in the arsenic contaminated soil compared to non-contaminated soil. Microorganisms are used in this process because the reduction rate of these metals is often slow unless catalyzed by microbial interactions  Research is also underway to develop methods to remove metals from water by enhancing the sorption of the metal to cell walls .
Plants use solar energy through photosynthesis to extract chemicals from the soil and to deposit them in the above-ground part of their bodies, or to convert them to a less toxic form.
It could favor the alkaline soil. Klassen and Watkins [ 36 ] reported that lead impairs communication between cells and modification of neuronal circuitry.
Arsenate-resistant microbes reduce arsenate into arsenite, which allows the transport of toxic form from the cell [ 38 ].
There are several ways to remove the heavy metals from various contaminated sources. The above-mentioned studies of bioremediation research are just representative examples of the wide range of on-going research in the field of bacterial- assisted nuclear waste bioremediation. In immobilizing the radioactive uranium species on the S-layer, it becomes much easier to remove large amounts of the radionuclide.
According to Bindler et al. The mixture forms a solidified matrix with the waste.
The stabilization and solidification techniques can occur both in situ or ex situ. The common procedures are chemical precipitation, dialysis, ion exchange, reverse osmosis and solvent extraction. Shewanella oneidensis, an organism capable of accumulating Uranium within its cell membrane.
The rhizofiltration is useful for both terrestrial and aquatic plants for in-situ or ex-situ purposes. Siderophores are specific iron chelating legends and are able to bind to other metals, such as magnesium, manganese, chromium, gallium and radionuclide, such as plutonium.
In water, it can survive in presence and absence of oxygen and also in presence of hazardous compounds or waste stream [ 24 ]. Mechanisms of Bioremediation by Plants 2.
Arsenic can appear in inorganic or organic forms and it has neurotoxic effect on both peripheral and central nervous systems.
Arsenate-resistant microbes reduce arsenate into arsenite, which allows the transport of toxic form from the cell [ 38 ]. Similar to how many microbes increase metal solubility, some, such as the uranium-reducing Desulfovibrio desulfuricans, are capable of directly reducing or oxidizing metal ions to decrease their solubility - reducing U VI to U IV in the case of D.
The metals always have been associated with metalloproteins and enzymes as co-factors. Thus, in general the immobilization and mobilization are the two the main techniques used for the bioremediation of metals by microbes.
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.
Immobilization Immobilization is a technique used to reduce the mobility of contaminants by altering the physical or chemical characteristics of the contaminant.The persistence of heavy metals in the environment may pollute or contaminate soils and aqueous streams as both natural components or as the result of human activity.
Bioremediation process in this regards is an option that offers the possibility to destroy or render harmless various contaminants using plants and microbes.
Amongst the various bioremediation processes, phytoremediation and. Biotechnological advances in bioremediation of heavy metals tools through cell manipulation to develop alternative and innovative methods aimed at pure and more effective ways for producing traditional products and at the same time nuclear waste, land mines, surface wastewater/sub-surface.
Abestract:Heavy metal pollution has become a major environmental concern nowadays and the bioremediation of polluted soil is an increasingly popular strategy due to both its efﬁciency and safety.
Low cost mitigation. Keywords: Bioremediation, Heavy metals contamination, Pollutants, Microorganisms like bacteria and fungi Ex situ bioremediation, In situ bioremediation I.
Introduction Today environmental pollution is a very big problem because of hazardous waste has led to scarcity of. HEAVY METAL REMEDIATION TECHNOLOGIES: REVIEW J.
Burlakovs bioremediation, problems concerning heavy metal contaminated areas in Latvia. 1. CRITERIA FOR SELECTION OF REMEDIATION METHODS. Bioremediation of Radioactive Waste From the Sea. Print Reference this.
Published: 23rd March, Last Edited: heavy metals such as mercury, and solvents such as toluene (14). it is most liable and comfortable to genetic manipulation due to its natural transformability by both high molecular weight chromosomal DNA and plasmid DNA (Download