- Copyright ©2007. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.
Surfactant-enhanced washing has become a very important option for the remediation of soils contaminated with a variety of compounds and elements, i.e., petroleum hydrocarbons, pesticides, dense nonaqueous-phase liquids, metals, and others. The use of biosurfactants has merged as an interesting solution. Many authors have published the use of soil-washing processes by means of biosurfactants produced by different bacteria to clean soils contaminated mainly with petroleum hydrocarbons, metals, and pesticides. The use of natural products produced by plants has been less explored. There are two basic aims of this study: first, to compare the performance of two natural gums (guar and locust bean gum [LBG]) with a synthetic surfactant sodium dodecyl sulfate (SDS), in terms of their total petroleum hydrocarbon (TPH) removal capabilities; second, to evaluate the behavior of these natural products (guar and LBG) combined separately with two synthetic surfactants (SDS or polyethoxylated sorbitan monooleate [TW80]), with respect to both TPH removal and removal efficiencies.
When a soil highly contaminated with Mexican crude (about 98,000 mg/kg) was cleaned with guar and LBG, TPH removal values as high as 49.6 and 47.7% were obtained, using gums at concentrations of 0.5%, in comparison with 36.3% of TPH removal, reached by SDS at the same surfactant concentration. Importantly, note that the soil contained TPH-diesel; TPH-gasoline and heavier fractions including benzene, toluene, ethyl benzene and xylene, polyaromatic hydrocarbons; and metals, including high amounts of calcium and magnesium.
Luis G. Torres has had experiences in industrial wastewater biological treatment and characterization, and remediation of metal- and petroleum-contaminated soils. Currently, he has focused his interest on surfactant application to environmental problems. His main research lines are (1) surfactant-enhanced biodegradation of aged petroleum fractions in soils, (2) in-situ and ex-situ soil washing, (3) preparation of petroleum fractions-surfactant-water emulsions, as a first step for fuel biotreatment (e.g., biodesulfuration), and (4) rheology and mixing of sludges and suspensions applied to environmental problems solution.
Patricia Zavala has a biochemical engineering degree from Universidad Autonoma Metropolitana (UAM)-Iztapalapa. She has a Min. Sc. (environmental science and engineering) degree from the UAM-Azcapotzalco. This paper is part of her M.Sc. thesis. She has experience on wastewater treatment as well as soil remediation using surfactants.
Margarita Beltrán-Villavicencio is a professor of environmental and chemical engineering at the Department of Energy, Autonomous Metropolitan University. Her research has focused on chemical processes, soil aquifer remediation, and specifically, phytoremediation of soils polluted with heavy metals and hydrocarbons. She is the coauthor of three textbooks in chemical engineering and a number of research articles in the area.
Mabel Vaca-Mier is a professor of environmental engineering at the Department of Energy, Autonomous Meropolitan University. She has an M.Sc. degree from McGill University (Canada) and a Ph.D. on Environmental engineering from Universidad Nacional Autonoma de Mexico (UNAM) (Mexico). Her research interests are water and wastewater pollution control and reuse, soil and aquifer remediation, and hazardous wastes treatment. She is the coauthor of a number of articles on the topic.
Rosario Iturbe has a Ph.D. in hydraulic engineering by UNAM. She has great experience on contaminants migration, groundwaters contamination and remediation, and petroleum-contaminated soils characterization and treatment by means of physichochemical and biological processes (i.e., in-situ and ex-situ soil washing, biopiles, air soil vapor extraction, surfactant-enhanced biodegradation of aged petroleum fractions). Currently, she is a researcher and group leader of the Soil and Aquifers Remediation Group at the Environmental Engineering Department of the Engineering Institute of UNAM.