Bioreactors bioremediation

Ex situ bioremediation may use various biological wastewater treatment processes, soil piles, or land appHcation. With in situ bioremediation, the basic process is the same microbes, soil, and water working together as a bioreactor. Where the in situ techniques differ are in how contaminants and microbes are brought in contact and how oxygen, nutrients, and other chemical supplements ate distributed in the soil—water—air matrix. Typical in situ bioremediation techniques include natural or intrinsic attenuation, air sparging, and bioventing. 

At present, photosynthetic organisms are not generally used as biocatalysts for bioconversion of organic compounds except for bioremediation of pollutants in the environment, although they are environment-friendly catalysts, and they may contain unusual type of enzymes to establish new reactions. Development of bioreactors specially developed for photosynthefic organism-catalyzed reaction as well as finding effective photosynthetic organisms as a biocatalyst are required in the future. 

A summary of the maximum concentrations that must be attained at contaminated sites after bioremediation, and discussion and exemplification of the various strategies that may be used—in situ, on-site, and bioreactors (Wilson and Jones 1993). 

The significance of this approach is that not only were the wastes treated at a very concentrated level using anaerobic and aerobic treatment, but the removals were extremely good. The implications for enhanced bioremediation suggest that some combination of aerobic and/anaerobic processes where nutrients are applied to the waste site and collected beneath the waste site could turn the entire waste site into an efficient bioreactor. These are interesting possibilities and the possibility of using a flooded system or other top down distribution system which recycles wastes from beneath the contaminated sites and returns it to the surface is an... 

Gonzalez-Gonzalez, L.R. Buenrostro-Zagal, J.F. Luna-Martinez, A.D. Sandoval-Gomez, Y.G. Schettino-Bermudez, B.S. Treatment of an herbicide-contaminated wastewater in a membrane bioreactor by sulfate-reducing consortia. Proceedings, 7th International Symposium on In Situ and On-Site Bioremediation, Orlando, Florida, June 2-5, 2003. 

Bioremediation is not effective in the removal of metals, cyanides, and some chlorinated compounds. High levels of some contaminants may inhibit biological activity in the treatment system. A treatability study is typically performed prior to initiation of a full-scale treatment system to determine the applicability of slnrry-phase bioremediation. If ambient temperatures are low, heating of the bioreactor may be required. 

Molasses has been used in slurry-phase bioreactors to encourage the bioremediation of explosives. The costs of this ex situ system were calculated based on the pilot-scale demonstration at the Joliet Army Ammunition Plant in Joliet, Illinois. The projected costs of a full-scale remediation using the slurry-phase treatment system ranged from 290 to 350/yd (D210571, p. 67). 

According to the vendor. Pintail Systems, Inc. s, bioremediation processes are less expensive than engineered technologies because the majority of the Pintail methods are in situ. For ex situ applications, the construction of bioreactors accounts for the greatest costs. The vendor claims that the following factors reduce costs compared to alternative technologies ... 

The Biolift slurry bioreactor is an ex situ technology for the bioremediation of soil or sludges contaminated with organic hazardous wastes. Slurry-phase bioremediation, while more costly... 

Trans Coastal Marine Services (formerly Envirosystems, Inc.) and Louisiana State University (LSU) have developed several bioreactor systems to facihtate petroleum hydrocarbon mineralization and the bioremediation of organic wood preservatives utilizing an immobilized microbe bioreactor (IMBR) technology. These technologies can treat petroleum hydrocarbons, chlorinated solvents, pesticide-contaminated soils, and contaminated groundwater. 

Reynolds, C M.,Travis, M. D., Braley, W. A. Scholze, R. J. (1994). Applying field-expedient bioreactors and landfarming in Alaskan climates. In Hydrocarbon Bioremediation, ed. R. E. Hinchee, B. C. Alleman, R. E. Hoeppel R. N. Miller, pp. 100-6. Boca Raton, FL Lewis Publishers. 

Some technical limitations to solid-phase PAH bioremediation exist. As compared with bioreactor operations, extended periods of treatment time will predictably be required with solid-phase PAH bioremediation operations. In many cases this is quite acceptable, especially when solid-phase systems are designed to... 

The treatment of PAH-contaminated soil in a reactor environment is basically limited to the use of soil slurry reactors. Conversely, many different bioreactor designs exist for the treatment of water contaminated with PAHs. As reviewed by Grady (1989) and Grady Lim (1980), these include fixed film reactors, plug flow reactors, and a variety of gas-phase systems, to name a few. Given the depth and magnitude of such a topic, for the purposes of this review discussions will be limited to a generic overview of reactor applications for PAH bioremediation. 

There are a number of engineering variations of in situ bioremediation strategies potentially applicable for soil and/or groundwater contaminated by PAHs. Recent reviews of in situ bioremediation technologies by Norris et al. (1993) provide excellent sources of references and offer case studies for myriad in situ bioremediation applications. These include bioventing vadose zone soil, biosparging saturated zone soil, vacuum-vaporized well (UVB) technology, and in situ bioreactors. 

Glaser, J.A., McCauley, P.T., Dosani, M. A., Platt, J.S. Krishan, E. R. (1994). Engineering optimization of slurry bioreactors for treating hazardous wastes. In Proceedings, Symposium on Bioremediation of Hazardous Wastes Research, Development and Field Evaluations, pp. 109-15. EPA/600/R-94/075. 

Mueller, J. G., Lantz, S. E., Colvin, R.J., Ross, D., Middaugh, D. P. Pritchard, P. H. (1993a). Strategy using bioreactors and specially selected microorganisms for bioremediation of ground water contaminated with creosote and pentachlorophenol. Environmental Science Technology, 27, 691-8. 

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