NATURAL BIOREMEDIATION PERSPECTIVE FOR BTX-CONTAMINATED GROUNDWATER IN BRAZIL - EFFECT OF ETHANOL

Natural bioremediation, the use of indigenous microorganisms to degrad e hazardous substances within aquifers without engineered stimulation, shows great promise as a cost-effective approach to hydrocarbon plume management. This technique requires thorough site characterization an d monitoring to verify that the natural attenuation processes continue to provide adequate risk protection. Significant progress has been ma de towards understanding the hydrogeochemical and microbiological fact ors that influence the feasibility of natural bioremediation of fuel-c ontaminated aquifers in North America and Europe. Nevertheless, this e xperience should be extrapolated with care to contaminated sites in Br azil, where gasoline contains about 22% of ethanol. Preliminary labora tory studies show that ethanol can enhance the solubilization of BTX i n water, and it might exert diauxic effects during BTX biodegradation. A better understanding of the biochemical, physical, and ecological e ffects of ethanol is needed to develop a rational basis for the select ion, mathematical modeling, and monitoring of appropriate natural bior emediation systems in Brazil. Copyright (C) 1996 IAWQ.