Soil systems bioremediation

TOllO Biorem Technologies, Inc., Soil Pile Bioremediation T0113 Bioremediation Service, Inc., AquaPlant Biofilter System T0114 Bioremediation Technology Services, Inc., BTS Method... 

Bio-Spin is an ex situ, bioremediation technology that treats soils contaminated with petroleum hydrocarbons. According to the vendor, the Bio-Spin system first screens and separates oversized debris. Then the system adds enzymes, uses rotation to mix the enzymes and contaminated soil, and then discharges the treated soil into a stockpile. The treated soil is kept separate from surrounding soils until bioremediation is complete. 

Hydrocarbon Environmental Recovery Systems bioremediation response advancement technologies (BRAT) are biological remediation products for treatment of organic contaminants in soil or water. According to the vendor this technology has been applied full scale at a number... 

One of the major obstacles in bioremediation of soils contaminated with synthetic organic compounds is the failure of laboratory remediation schemes to simulate the impact of field soil conditions on both the contaminant and the microorganism (Rao et al., 1993)- The purpose of this chapter is to introduce those topics which must be considered in order to develop an effective bioremediation strategy for soils contaminated with organic pollutants. My emphasis is on providing a comprehensive overview of the complexity of the soil system as it relates to bioremediation. 

In summary, extrapolation of reactions determined in homogeneous solutions to the soil system may not result in accurate predictions of possible products. Unanticipated abiotic reactions which occur during bioremediation may influence the products, causing altered degradative pathways of the contaminants. These pathways may be site specific because of differences in abiotic catalysts. Abiotic reactions may occur to both the parent compound or to intermediates formed during biotic alteration of the compound. Bioremediation efforts should include the possibility of site specific abiotic reactions. 

Bioremediation has been successfully demonstrated for a variety of contaminant classifications. The majority of the studies have focused on petroleum compounds (BTEX, gasoline, diesel, jet fuel, etc.) because of their widespread occurrence as a contaminant. The other major waste classifications where bioremediation has been successful are solvents (toluene, trichloroethylene, etc.), creosote, pulp and paper, pesticides, textiles, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). Table 1 contains a partial list of the microbial genus successfully implemented for these contaminants. For aqueous petroleum contaminants, bacteria and yeasts are the most prevalent degraders. In contaminated soil systems, bacteria and fungi are the microorganisms responsible for degradation. ... 

The efficient removal or permanent immobilization of metals achieved by current techniques such as physical extraction, chemical leaching, and vitrification results in both soil structure and fertility detriment. On the other hand, remediation technologies based on biological systems (bioremediation and phytoremediation) seem to be sound processes that enhance the natural response of soil to heavy metal contamination. In these cases, the slow rates of heavy metal removal in soil are strong drawbacks to scaling up the processes for technological applications. 

In Situ Bioremediation. In situ bioremediation can be an aerobic or anaerobic process, or a combination of the two. In designing an in situ bioremediation system, one should consider the types of microorganisms available (naturally in place or added), the stmctural and chemical makeup of the soil matrix, types of contaminants, oxygen and nutrient addition and distribution, and temperature. These factors are discussed prior to introducing the individual techniques for in situ bioremediation. 

Remediation aetivities at North Cavaleade ineluded the installation, operation, and elosure of a bioremediation system to treat eonta-minated soil. 

Xenobiotics exist not only in the free state but also in association with organic and mineral components of particles in the water mass, and the soil and sediment phases. This association is a central determinant of the persistence of xenobiotics in the environment, since the extent to which the reactions are reversible is generally unknown. Such residues may therefore be inaccessible to microbial attack and apparently persistent. This is a critical factor in determining the effectiveness of bioremediation (Harkness et al. 1993). Although the most persuasive evidence for the significance of reduced bioavailability comes from data on the persistence of agrochemicals in terrestrial systems (Calderbank 1989), the principles can be translated with modification to aquatic and sediment phases that contain organic matter that resembles structurally that of soils. 

Regardless of whether the microbes are native or artificially introduced into the soil, it is important to understand the mechanisms by which they degrade or detoxify hazardous pollutants through their metabolic activity. Understanding these mechanisms is essential for the proper design of bioremediation systems that provide the optimum conditions and the required nutritional supplements for the specific microbial process. 

Treatment in a pit (Figure 14.9) can be carried out in the same area from which the soil was excavated, following isolation of the area with an impermeable liner. In this case, the upper surface of the pit can be covered with asphalt and rendered for use before the completion of the bioremediation project. If the upper surface is covered, an appropriate venting system must be installed to... 

The following design example of an injection and extraction system (Figure 18.7) illustrates the bioremediation process. Both the soil and groundwater are contaminated. Groundwater is extracted downgradient and reinjected upgradient of the zone of contamination. Water is also injected to flush... 

A full-scale cleanup was performed using in situ bioremediation to treat MTBE and BTEX at a service station in Massachusetts. Soil at the site consists of a layer of sand and gravel underlain by peat, silt, and clay. The in situ bioremediation system consisted of 12 injection wells and two butane injection panels used to stimulate cometabolic aerobic biodegradation of the contaminants in groundwater. The system was operated between October 2000 and January 2001. MTBE concentrations were reduced from 370 to 12 pg/L and BTEX contamination in groundwater was reduced by approximately two orders of magnitude during the 4-month period.74... 

A bioslurry phase system consists of the suspension of a solid phase in water or other liquid medium to a concentration typically between 5% and 40% (w/v) and kept under agitation conditions to allow the microbial growth of the indigenous microbiota or a particular inoculated microorganism [114], Bioslurry systems for bioremediation purposes have been mostly conducted with bacterial cultures [146, 147], although in the last few years WRF were also successfully applied to soil bioremediation of PAHs, hexachlorocyclohexane and pentachlorophenol [110, 113, 114],... 

McLean JS, Lee J-U, Beveridge TL (2002) Interactions of bacteria and environmental metals, fine-grained mineral development and bioremediation strategies. In Huang PM, Bollag J-M, Senesi N (eds) Interactions between soil particles and microorganisms. Impact on the terrestrial ecosystem, vol 8, IUPAC series on analytical and physical chemistry of environmental systems. Wiley Chichester UK, pp 227-261... 

A recent experiment compared for the first time pollutant degradation by chemotactic bacteria and nonchemotactic mutants [54]. The result suggested an important role of chemotaxis in the bioremediation of contaminated soils. In a heterogeneous system, in which naphthalene was supplied from a microcapillary, a 90% reduction in the initial amount of naphthalene took six hours with the chemotactic wild-type Pseudomonas putida PpG7, while a similar reduction with either a chemotaxis-negative or a nonmotile mutant strain took about five times longer. Only the systems inoculated with the chemotactic strain exhibited degradation rates in excess of the rate of naphthalene diffusion from the... 

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