Showing papers by "Pedro J. J. Alvarez published in 1996"
TL;DR: In this paper, chemical effects and microbial response after Fenton's treatment of pendimethalin contaminated soils were assessed and it was found that the highest efficiency was associated with a soil having comparatively low organic matter and low acid neutralizing capacity.
111 citations
TL;DR: The use of indigenous microorganisms to degrade hazardous substances within aquifers without engineered stimulation, shows great promise as a cost-effective approach to hydrocarbon plume management.
49 citations
TL;DR: The use of indigenous microorganisms to degrade hazardous substances within aquifiers without engineered stimulation shows great promise as a cost-effective approach to hydrocarbon plume management as discussed by the authors, but this technique requires thorough site characterization and monitoring to verify that the natural attenuation processes continue to provide adequate risk protection.
Abstract: Intrinsic bioremediation, the use of indigenous microorganisms to degrade hazardous substances within aquifiers without engineered stimulation, shows great promise as a cost-effective approach to hydrocarbon plume management. This technique requires thorough site characterization and monitoring to verify that the natural attenuation processes continue to provide adequate risk protection. Significant progress has been made towards understanding the hydrogeochemical and microbiological factors that influence the feasibility of intrinsic bioremediation of fuel-contaminated aquifers in North America and Europe. Nevertheless, this experience should be extrapolated with care to contaminated sites in Brazil, where gasoline contains about 22% of ethanol. Preliminary laboratory studies show that ethanol can enhance the solubilization of BTX in water, and it might exert diauxic effects during BTX biodegradation. A better understanding of the biochemical, physical, and ecological effects of ethanol is needed to develop a rational basis for the selection, mathematical modeling, and monitoring of appropriate intrinsic bioremediation systems in Brazil. 29 refs., 3 figs.
19 citations
Journal Article•
10 citations
TL;DR: It is suggested that nitrate addition to oxygen-limited aquifers might enhance BTX bioremediation not only by supplementing the electron acceptor pool as is widely accepted, but also by fostering favorable changes in the composition of the microbial consortium.
5 citations
1 citations
01 Jan 1996
TL;DR: Aquifer microcosms were used to investigate the effect of stimulating denitrification on microbial population shifts and BTX degradation potential as discussed by the authors, and the results suggest that nitrate addition to oxygen-limited aquifers might enhance BTX bioremediation not only by supplementing the electron acceptor pool as is widely accepted, but also by fostering favorable changes in the composition of the microbial consortium.
Abstract: Aquifer microcosms were used to investigate the effect of stimulating denitrification on microbial population shifts and BTX degradation potential. Selective pressure for facultative denitrifiers was applied to a treatment set by feeding acetate and nitrate, and cycling electron acceptor conditions twice between aerobic and denitrifying stages. A second (control) set degraded the same amount of acetate under aerobic conditions. The resulting concentrations of total heterotrophs were not significantly different between the two sets. Nevertheless, the concentrations of denitrifiers, Pseudomonas spp., and BTX degraders were significantly higher in the cycled microcosms than in the aerobic controls. The predominant isolates from the cycled microcosms were fluorescent Pseudomonas species that are known to degrade BTX. Following the complete removal of acetate, cycled microcosms also showed higher aerobic BTX degradation activity. These results suggest that nitrate addition to oxygen-limited aquifers might enhance BTX bioremediation not only by supplementing the electron acceptor pool as is widely accepted, but also by fostering favorable changes in the composition of the microbial consortium. Specifically, denitrifying conditions could have the ancillary benefit of fortuitously selecting for Pseudomonas spp. that can degrade BTX. This syllogism is supported by a survey of international soils (from France, Denmark, Brazil and Iowa, USA), which showed a correlation between the concentration of denitrifers and Pseudomonas spp. Copyright © 1996 Elsevier Science Ltd
1 citations