Diesel degradation in soil catalyzed by the addition of a bioagent

Abstract

The supernatant harvested from a mesophilic, molasses-fed, non-methanogenic bioreactor, which is rich in nitrogen, phosphorous, metals, free amino acids, Sporolactobacillus sp., Prevotella sp., and Clostridium sp., is diluted with tap water and tested as the bioagent to catalyze diesel degradation in soil. Outdoor experiments are performed under the following conditions to assess the effectiveness of the bioagent: diesel doses: 9–15 mg TPH/g soil; bioagent concentrations and dose: 1–5 % at 60 ml/day; soil sample size: 600 g; ambient temperatures: 28–32 °C, and relative humidity: 40–82 % (TPH: total petroleum hydrocarbons). Diesel degradation in soil treated with 3 % bioagent, which proceeds at the rates of 1.04–1.55 mg TPH/g soil-day, is completed in about a week with up to 83 % efficiencies. In contrast, diesel degradation in soil sprinkled with water (60 ml/day) proceeds at the rate of 0.3 mg TPH/g soil-day that achieves 15–22 % degradation efficiencies. The addition of 3 % bioagent yields desired soil moisture content (10–15 %), soil pH (6.8–8.2), and nutrition inputs. Both Sporolactobacillus sp. and Prevotella sp. grown on molasses are robust, tolerant high diesel doses, able to utilize hydrophobic hydrocarbons, and readily adaptable to the soil environment. Most notably, prior acclimatization is not required to enable these properties.