Soil Bioremediation. Группа авторов

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Soil Bioremediation - Группа авторов


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the most widely used technological treatment for the restoration of polluted environments [36, 37, 40, 41]. One‐fourth of all remediation projects make use of in‐situ bioremediation strategies [36]. In‐situ bioremediation technology is less expensive because it does not need evacuation and it also releases fewer pollutants. The other important aspect of in‐situ bioremediation process is its applicability to diverse environmental niches for example, industrial sites, aquifers [42], soil subsurface [43], and groundwater [35, 44]. The significance of in‐situ bioremediation is increased by abundant presence and activity of microorganisms, thereby enhancing the efficiency of the decontamination process even in non‐accessible environments. Ex‐situ bioremediation is carried out by several methods, which are non‐related, e.g., slurry phase bioremediation and solid‐phase bioremediation, which are driven by the physico‐chemical properties of contaminants [45, 46]. In‐situ bioremediation techniques can be categorized as (i) biostimulation or (ii) bioaugmentation [36, 40, 41, 47] and focus mainly on speeding up the removal of toxic pollutants. The choice between the two techniques is determined by: the physico‐chemical characteristics of the polluted area, the presence of co‐contaminants, and the type and concentration of the pollutant, for example. It is suggested that ex‐situ bioremediation methods are useful for the remediation of (i) soils polluted with recalcitrant pollutants in higher concentrations, (ii) soils rich in clay where the permeability of pollutants is low, (iii) sites where conditions are not favorable for biological activities, and (iv) where microorganisms are not released for a range of reasons [48]. The selection of a bioremediation technique based on the expected outcome is very important. The enhanced degradation by in‐situ bioremediation can result in increased contamination of lesser hydrophobic metabolites in the water sources in the vicinity of the source contamination [49, 50].

      1.3.1 Bioaugmentation

Aspects Depiction References
Microbial viability loss during inoculation Sudden changes in environmental conditions [67]
Death of microbes after inoculation Presence of toxic pollutants and nutrient depletion [58, 60]
Competition Competition for nutrients by autochthonous microbes [23, 51]
Predation Overgrowth of protozoa [68]
pH pH change inhibits growth of microbes [69]
Temperature Affects the nature of oil vis a vis microorganisms [70]
Moisture Growth and metabolism are lowered by low moisture content and higher moisture content reduces aeration [61, 69]

      1.3.2 Biostimulation


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