Bioremedation

Bioremediation


Generally stated, the phrase "in situ bioremediation" refers to a broad spectrum of bioremediation techniques and technologies that rely on the capabilities of indigenous or introduced micro-organisms to degrade, destroy or otherwise alter objectionable chemicals in soil and ground water. Three factors affect the success of bioremediation.

These are (1) the type of organisms, (2) the type of contaminant, and (3) the geological or chemical conditions at the contaminated site. The key players in bioremediation are bacteria. Bioremediation is an extension of the natural function of existing microorganisms to break down human, animal and plant wastes. Typically, bioremediation systems rely on microorganisms indigenous to the contaminated site. An emergent technology involves injection of microbes to augment biodegradation at contaminated sites. A critical factor in determining whether bioremediation is appropriate at a site is whether the contaminants are susceptible to biodegradation. Bioremediation is well established for certain types of petroleum hydrocarbons and their derivatives, including gasoline, fuel oil, alcohols, ketones, and esters. For other types of organic contaminants, such as solvents, bioremediation has been successfully tested in the laboratory and at a limited number of field sites. The amenability of the subsurface environment to bioremediation depends, in part, on whether the bioremediation will be intrinsic or engineered. Intrinsic bioremediation utilizes the innate capabilities of naturally occurring microbes without any enhancements. Engineered bioremediation accelerates microbial activity by site-modification procedures, such as by introduction of microbes or the installation of wells to circulate fluids and nutrients that stimulate microbial growth. The case studies in this report focus only on engineered bioremediation. Proponents of bioremediation say it is a less costly, faster, and safer method for the clean up of contaminated soil than more conventional clean-up methods. Likewise, they assert that conventional methods of soil clean up involve excavation and treatment or disposal elsewhere with increased exposure to contaminants for both workers and neighbours.

Stages of treatment (field works):
    • Ripping on depth of pollution with the purpose of improvement of ground structure and its airing by atmospheric air (for this purpose a wheeled tractor with shed plough will be used);

    • Fungoid compost, which carries out a number of functions: а) a source of microorganisms � destructors of hydrocarbons; б) ripper, improves physical and chemical and аgrоchemical properties of the polluted ground (increases capacity of absorption and water-holding capacity; c) source of бiоgenic elements - nitrogen, phosphorus etc.

    • Mineral fertilizers. As mineral fertilizers ammophos will be used, containing in its structure all three biogenic elements in the ratio necessary for microorganisms. The quantity of applicated mineral fertilizers will be calculated on the basis of given chemical analysis of the initial hydrocarbons content in soil. In a basis of calculations the rule about an optimum ratio of C: N in soil 25-30:5 is used.