Hydrocarbon-contaminated drill mud waste associated with oil and gas activities constitutes a major risk to the environment, but current conventional treatment methods have not been effective in removing Total Petroleum Hydrocarbon (TPH). In this study, the remedial potential of nutrients addition to stimulate the growth of indigenous microbes was harnessed to treat drill mud contaminated with hydrocarbons as an alternative to the conventional treatment methods.
Baseline study of the hydrocarbon contaminated drill mud was carried out to establish the inherent physicochemical and biological characteristics. Homogenized sample of the hydrocarbon contaminated drill mud was inoculated with adequate amount of nutrient and bulking agent into various ratios of contaminated drill mud/nutrients/bulking agent. The specification for each microcosm experiment was 0.2 m × 0.5 m × 1.5 m for depth, breadth and length respectively.
The experimental results showed a high TPH level of 8.88 × 105 mg/kg, low nitrogen content of 0.4% and low microbial load of 1.34 × 103 CFU/100ml for the drill mud. TPH degraded sharply, averaging 98% after three weeks and 99.5% after seven weeks augmentation with nutrients. The trends of the other measured parameters supported that the degradation was due to the enhanced microbial activities.
The high rate of degradation achieved in this study supports the proposition that bioremediation of drill mud is a feasible approach to effectively remove TPH components from the hydrocarbon contaminated drill mud. This study therefore paves way for scalable studies to be pursued in similar and/or different industrial situations.