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The aim of this study was to investigate the feasibility of using apple filter cake, a fruit-processing waste to enhance the bioremediation of petroleum contaminated soil. A rotating barrel system was used to study the bioconversion of the xenobiotic compound by natural occurring microbial population. The soil had been accidentally polluted with a total petroleum hydrocarbon concentration of 41,000 ppm. Although this global value was maintained during the process, microbial intervention was evidenced through transformation of the petroleum fractions. Thus, fractions that represent a risk for the environment (GRO, Gasoline Range Organics i.e., C6 to C10–12; DRO, Diesel Range Organics i.e., C8–12 to C24–26 and RRO, Residual Range Organics i.e., C25 to C35) were significantly reduced, from 2.95% to 1.39%. On the contrary, heavier weight fraction from C35 plus other organics increased in value from 1.15% to 3.00%. The noticeable diminution of low molecular weight hydrocarbons content and hence environmental risk by the process plus the improvement of the physical characteristics of the soil, are promising results with regard to future application at large scale.

The objective of the following work is to show the different techniques applied for the recovery of passive environmental and the convenience of the application of each one in the different cases. In the Refinery of Lujan of Cuyo of Repsol - YPF S.A. were existing environmental passives of different characteristics. One of them was consisting of pools to sky opened without waterproofing that was containing a volume of flowing material of approximately of 20000 m3 of mud contaminate with heavy and light hydrocarbons, phenol, exhausted caustics, mercury, lead and other metals in high concentrations. The other was consisting of a surface of approximately 50000 square meters of contaminated soils with hydrocarbons originating from funds of tanks and dry muds resulting of the continuous centrifugation of muds. Complying with the commitment assumed his environmental policy of remedying the passive, the Refinery beginning an investigation program to find the more convenient alternatives for each case. At the moment of considering the alternatives of solution they have had into account technical, environmental and economic aspects. After analyzing the various existing technologies was opted for using two types of different treatments as compared to the different realities that was presenting each case. In the first case was opted for the stabilization technique that was developed in the area of the refinery, in base to tests accomplished at plant level pilot. Surpassed this stage were begun the tests to industrial scale what permitted to solve the problem in a period of 6 months. In the second case was opted for the use of bioremediation techniques: landfarming and aerated accumulation. These techniques were developed along with the National University of Cuyo. In either cases it is accomplished a monitoring of the results with the University and the organs of environmental control, being obtained successful results, with the recovery of the discussed soil.

TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract

The aim of this work was to evaluate the composting technology in the treatment of soils contaminated with weathered hydrocarbons and drilling cuttings commonly placed in repositories under specific regional conditions. The composting technology to remediate contaminated soils, consists in the addition of organic material and periodic aeration so that the biodegradation of hazardous organic pollutants and organic matter is favored in a simultaneous process. In November 2005, a pilot experiment was set up on a location owned by RepsolYPF in the Province of Mendoza, Argentina. Ninety cubic meters of soil contaminated with hydrocarbons were treated under three experimental conditions: two windrows for treatment A (contaminated soil + goat manure, a by-product of the farming activity of the region); two windrows for treatment B (contaminated soil + goat manure + sawdust + sulphur); and two control windrows for treatment C. All the treatments had an aeration system which guaranteed the aerobic process. Five samples were taken throughout six months of treatment. The variables analyzed were soil physical and chemical parameters, hydrocarbons concentration, microbiological studies and ecotoxicological tests. The results are encouraging concerning the quality of treated soils: there was a decrease of the toxicity in treatments A and B, an increase in the microbiological diversity, especially for the fungi group, a stimulation of the biological activity (nitrification, humic acid content) and a decrease in the hydrocarbon concentration. Treatment B turned out to be the most efficient way to obtain a high quality soil. This final product will be used as soil amendment in a well site restoration. Introduction The persistence of petroleum contaminants in soils is a matter of significant industrial, scientific and regulatory concern because of the potential damage to natural flora and fauna, its ability to concentrate up the trophic ladder and possible consequences on animal and human health. These concerns continue to drive the need for the development and application of remediation strategies for the restoration and rehabilitation of contaminated soils under environment friendly considerations. Under these premises, composting was the eligible technique for the treatment of soil contaminated with weathered hydrocarbons at a location owned by Repsol YPF in Malargüe, province of Mendoza, Argentina. Microbial communities of soils always include strains with ability to use complex and recalcitrant substances, (Ercoli et al., 2000; Leahy and Colwell, 1990 ; Sugiura et al., 1997). However, the required period of time for natural biodegradation is too long, and in consequence bioremediation technologies have to be applied. Composting is a controlled biological process by which organic contaminants are converted by microorganisms (under aerobic and anaerobic conditions) to innocuous, stabilized by-products. Soils are excavated and mixed with bulking agents and organic amendments, such as wood chips, animal, and vegetative wastes, to enhance the porosity of the mixture to be decomposed. Vegetal materials act as bulking agents that lower soil bulk density, increase porosity and oxygen diffusion, and can help to form water-stable aggregates. These activities increase aeration and stimulate microorganisms to degrade organic materials resulting in thermogenesis, characteristic of composting, and production of organic and inorganic compounds. Although addition of organic material to contaminated soil is not a new concept for improving its remediation (Antizar-Ladislao et al., 2005; Namkoong et al., 2002; Rivera-Espinosa et al. 2004), the use of local waste materials in Argentina is an emerging alternative to accelerate TPH decomposition.