Evaluation of Bioremediation

Cardinal issues for assessing the effectiveness of bioremediation include the following  

Diminution in the concentration of the substrate(s) is not alone an acceptable measure of degradation, since loss may occur by volatilization or by transformation with the formation of transient or terminal metabolites. In addition there may be a continuous input, for 

The terrestrial environment is highly heterogeneous, so that representative sampling generally presents a serious problem, and the evaluation of spatial effectiveness is difficult 

The extent of leaching into groundwater may be difficult to evaluate, because few of the systems are sufficiently enclosed to make a convincing balance of the concentrations of the substrates and their metabolites—including CO2 or CH4—that are lost to the atmosphere. 

Most field environments are dynamic. There are therefore continuous changes in the input and in the metabolites that are being produced. Interpretation of chemical analyses may therefore be equivocal, and metabolites may be removed at different rates. One approach has been to use surrogate contaminants, for example, ( /Z)-chlorofluoroethene for chloro-ethene, in which only the E isomer is dechlorinated (Ennis et al. 2005). 

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Ward, C. H., Wilson, J. T., Kampbell, D. H. Hutchins, S. (1992). Performance and cost evaluation of bioremediation techniques for fuel spills. In Proceedings, Bioremediation Symposium, 1992. Niagara-On-The Lake, Ontario, Canada, September 20-24, 1992, pp. 15-21. 

Bachoon, D.S. Araujo, R. Molina, M. Hodson, R. Microbial community dynamics and evaluation of bioremediation strategies in oil-impacted... 

Joo, C.S. Oh, Y.S. Chung, W.J. Evaluation of bioremediation effectiveness by resolving rate-limiting parameters in diesel-contaminated soil. J. Microbiol. Biotechnol. 2001, 11 (4), 607-613. 

A Field Evaluation of Bioremediation of a Fuel Spill Using Hydrogen Peroxide... 

Swannell RPJ, Croft BC, Grant AL, Lee K (1995) Evaluation of bioremediation agents in beach microcosms. Spill Sci Technol Bull 2 151-159... 

Two sections deal briefly with procedures for investigating the pathways used in biodegradation and biotransformation. They cover briefly the application of isotopes, and of nondestructive methods that include NMR, EPR, and x-ray analysis. They should be viewed in the wider context of procedures for evaluating the effectiveness of bioremediation that are covered in Chapter 13 and their application in Chapter 14. 

A comparison had been made of fractionation during the dechlorination of tetrachlo-roethene by Sulfurospirillum multivorans and Desulfitobacterium sp. strain PCE-S in laboratory experiments (Nijenhuis et al. 2005). Isotope fractionation in growing cultures was 1.0052 for Desulfitobacterium sp. and only 1.00042 for Sulfurospirillum multivorans, whereas fractionation was greater in crude cell extracts from both strains. It was concluded that caution should therefore be exercised in applying fractionation factors to the evaluation of in situ bioremediation. 

Swannell RPJ, K Lee, M McDonagh (1996) Field evaluations of marine oil spill bioremediation. Microbiol Rev 60 342-365. 

Mueller JG, SE Lantz, BO Blattmann, PJ Chapman (1991a) Bench-scale evaluation of alternative biological treatment processes for the remediation of pentachlorophenol- and creosote-contaminated materials solid-phase bioremediation. Environ Sci Technol 25 1045-1055. 

It is appropriate at this stage to evaluate procedures that will be used to assess the effectiveness of bioremediation, which have been discussed in Chapter 13. These may include (a) use of radiolabeled substrates (although these will not generally be permitted in field operations) and the application of C-labeled substrates, (b) evaluation of the occurrence of metabolites, and (c) evaluation of markers such as specific enzymes. 

Wilson, J. T., Leach, L. E., Michalowski, J., Vandegrift, S., and Callaway, R., 1989, In-Situ Bioremediation of Spills from Underground Storage Tanks New Approaches for Site Characterization, Project Design, and Evaluation of Performance. U.S. Environmental Protection Agency Report No. EPA/60012-89/042, July, 56 pp. 

Ideally, the site characterization study has defined the vertical and horizontal extent of the contamination. Contoured site maps showing the (three-dimensional) distribution of the contaminants allow identification of areas that require extensive restoration, or may be allowed to be monitored to closure under natural attenuation. Knowledge of how much contamination exists and its location is the important first step in the remediation process. Evaluation of these data will permit consideration of the various remediation remedies available. Where the contaminant is contained within the shallow (<6 m) unsaturated zone and is recalcitrant (not readily biodegradable), excavation for off-site treatment or disposal may be the most expeditious procedure. Alternatively, depending on the contaminant, a variety of in situ procedures, including bioremediation, air sparging, soil vapor extraction, and fixation, may be applicable. 

Moreels, D., Bastiaens, L., Ollevier, F., Merckx, R., Diels, L., and Springael, D., 2004, Evaluation of the intrinsic MTBE biodegradation potential of European contaminated subsurface soils in microcosms simulating in sim bioremediation conditions, FEME... 

Sims, R. G, Sims, J.L., Sorensen, D. L., Stevens, D. K., Huling, S. G., Bledsoe, B. E., Matthews, J. E. Pope, D. (1994). Performance evaluation of full-scale in situ and ex situ bioremediation of creosote wastes in ground water and soils. In Proceedings, Symposium on Bioremediation of Hazardous Wastes Research, Development and Field Evaluations, pp. 35-9- EPA/600/R-94/075. Cincinnati, OH US EPA. 

Lamar, R.T. Glaser, J.A. (1994). Field evaluations of the remediation of soils contaminated with wood-preserving chemicals using lignin-degrading fungi. In Bioremediation of Chlorinated and Polycyclic Aromatic Hydrocarbon Compounds, ed. R. E. Hinchee, A. Leeson, L. Semprini S. K. Ong, pp. 239-47. Boca Raton, FL Lewis Publishers. 

Baud-Grasset, F., Baud-Grasset, S. and Safferman, S. I. 1993. Evaluation of the bioremediation of a contaminated soil with phytotoxicity tests. Chemosphere 26, 1365-1374... 

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