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What is Bioremediation Process and its Types
#13
Phytoremediation is another form of bioremediation involving plants. In recent times an increasing trend in land, surface and groundwater contamination from industrial and agricultural activities is becoming a major concern. Toxic environmental pollutants, including radionuclides, heavy metals, pesticides in soil, surface and ground water possess a major threat to the ecosystems. Conventional remediation practices of contaminated sites are often not useful due to limited potential, applicability to limited areas and huge cost. Moreover, these conventional techniques destroy the microenvironment often making the soil unsuitable for agriculture and infertile. Therefore, there is an emerging need to develop environmentally sound technologies (ESTs) considering the probable end use of the remediated site.
Let’s have a quick look at the Phytoremediation process
Phytoremediation is the process of removal; contaminated sites with plants alleviate environmental problems in a more ecofriendly manner.
It is a cost effective cleanup technique driven by solar energy, mostly useful in treating a wide range of environmental contaminants without generating toxic sludge.
Phytoremediation technique efficiently uses plant through their biological, chemical or physical processes for the removal, detoxification and/or immobilization of toxic contaminants in water soil and sediments. Plant systems are uniquely equipped with remarkable ability to adsorb along with transport systems that selectively takes up contaminants from water or soil. Growing plants are used in the process of phytoremediation at a contaminated site for a required period of growth to facilitate immobilisation, binding or detoxification of the pollutants. There are various ways that plants are used to remediate polluted sites. Plants have the ability to degrade organic contaminants and can stabilize heavy metals by acting as filters.
Plants primarily uptake contaminants through the root system, in which resides the principle mechanism of toxicity control. The enormous surface area is provided by the root system that helps in the absorption and accumulation of nutrients and water along with the non-essential toxic contaminants. Some plants can better remove contaminants as compared to others. Plants should therefore be suitably selected for the phytoremediation process so that they must be able to tolerate the various concentrations and types of pollutants present as well as withstand the climate of the area concerned. Another major concern is the depth of contamination. Grasses and ferns are used in the shallow contaminated region, whereas trees are used to remediate deeper contaminated and groundwater.
Phytoremediation therefore is an alternative technology that is applicable instead of conventional mechanical removal techniques that are energy and labour intensive and require huge capital inputs. It is an in situ technology for remediation utilizing the inherent potentiality of plants in environmental cleanup. It is an attractive, safe and low-risk method of remediation. Remediation with plants makes a site quite attractive. It is always advisable to use native plants as they are better adapted to the condition of the concerned region.
#14
The original post in this thread mentions one form of bioremediation called biostimulation “in which bacteria are motivated to start the process of bioremediation”. There are various examples in which the process of biostimulation can be used effectively to encourage the indigenous bacterial community to tackle environmental pollution. One recent study describes handling of the high concentrations of uranium (VI) generated from the mining of leachate in the Witwatersrand Basin, South Africa. In this study, tolerance of the indigenous bacterial species to high U(VI) concentrations along with the required amount of citric acid were optimised. Two bioreactor studies were performed. In the first, U(VI) was removed effectively from both low and high concentrations of U to below the levels set as safe for drinking water by South African National Standards. The second adapted to increasing U(VI) levels in feed water in the presence of sufficient electron donors. Relevant bacterial species such as Desulfovibrio and Geobacter were identified, which are known to reduce U(VI). Uranium was both precipitated intracellularly and as U(IV) oxides and TEM-EDS. The study confirmed the possibilities for optimising the tolerance of the indigenous bacteria for remediation of U(VI) and suggests that their system can be upscaled.

As previous posts have mentioned, it is important to be mindful of potential alterations in bacterial population diversity and abundance following bioremediation strategies including biostimulation. For example, one recent study examined consequences for bacterial abundance and diversity after biostimulation on anoxic marine sediments with high metal content. Molecular fingerprinting and next generation sequencing was used to characterise the bacterial population.  Adding organic (lactose and/or acetate) and/or inorganic compounds induced significant increases in bacterial growth but also changed bacterial diversity and assemblage composition. In experimental systems, supply of organic substrates only resulted in increases in the relative importance of sulphate reducing bacteria of the Desulfobacteraceae and Desulfobulbaceae families accompanied by a Flavobacteriaceae taxa. The opposite effect was achieved by when inorganic nutrients were also supplied. Increased bacterial metabolism along with the increase of bacterial taxa affiliated with Flavobacteriaceae resulted in a significant decrease of Cd and Zn associated with sedimentary organic matter and Pb and As associated with the residual fraction of the sediment. However, independent of the experimental conditions investigated, there was no dissolution of metals suggesting that bacterial assemblages were important in controlling metal solubilisation processes. The results of this study have thus clarified important biogeochemical interactions which influence metal behaviour and advance understanding of potential consequences of bio-treatments on fate of metals in contaminated marine sediments.

References
Maleke M, Williams P, Castillo J, Botes E, Ojo A, DeFlaun M, van Heerden E. Optimization of a bioremediation system of soluble uranium based on the biostimulation of an indigenous bacterial community. Environ Sci Pollut Res Int. 2014 Dec 30. [Epub ahead of print]

Fonti V, Beolchini F, Rocchetti L, Dell'Anno A. Bioremediation of contaminated marine sediments can enhance metal mobility due to changes of bacterial diversity. Water Res. 2014 doi: 10.1016/j.watres.2014.10.035. [Epub ahead of print]
 
 
 
 
 
#15
Do you have idea on difference between bioremediation and biodegradation with examples
  

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