Restoring A Coastal Soil Contaminated with Weathered Hydrocarbons through Bioestimulation, Bioventing and Bioagmented Technologies at Minimal Cost

Verónica Jimenez, and Ricardo Guerra

CIATEC, México

Abstract: The degradation of weathered hydrocarbons was studied in a laboratory level experimental design. Samples of contaminated soil were placed in 1 liter glass containers. The contaminated soil had an initial hydrocarbon concentration of 55,325±50 mg HF/kg dry soil. Two series of experiments were performed under the following conditions: 1) additions of Bioaugmented microbial consortium + injected air flow + moisture + optimized minimal medium (MM), 2) additions of Bioaugmented microbial consortium + injected air flow + moisture +Bushnell Haas enriched medium (BH). In both series the following operating parameters were varied: % moisture, airflow and nutrient level, each evaluated in low and high levels following a Plackett-Burman experiment design. The response variables were: HF (Heavy fraction)/kg dry soil content, the FTIR analysis, percentage organic matter, pH and electrical conductivity (mS/cm) of the soil. The results obtained showed a maximal removal of 41.3% HF/kg dry soil after 14 days of biodegradation with the following conditions: 40% moisture content, 80 L air/h with added nutrients. Alteration of some physicochemical characteristics of the soil were also observed at the end of the tests. The treatment that showed the high removal change from 5.5 (acidic) to 7.8±0.5 (neutral), and the EC (mS/cm) increased from 0.4±0.1 to 0.9±0.1 in the control. The experimental results indicated optimal operating parameters to enhance the bioavailability the weathered hydrocarbon contaminated soils at minimum cost.

Key words: bioventing, biostimulation, bioremediation, hydrocarbon recalcitrance