Aerobic fixed bed bioreactors were used to study and compare biostimulation and bioaugmentation for remediation of soil contaminated with spent motor oil. Bioaugmentation using consortium of bacteria and biostimulation using inorganic fertilizer and potassium dihydrogen orthophosphate were investigated. The bioremediation indicators used were the oil and grease content removals, total heterotrophic bacteria counts and carbon dioxide respiration rates. Results showed that biodegradations were very effective with 50, 66 and 75 % oil and grease content removal efficiencies for control, bioaugmentation and biostimulation respectively after ten weeks. Carbon dioxide respiration followed similar pattern as the oil and grease content removals. Biostimulation option has the highest carbon dioxide generation (6 249 mg/kg) and the control with the least (4 276 mg/kg). Therefore, the biostimulation option can be used to develop a realistic treatment technology for soils contaminated with spent motor oil.

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Some oil and gas reservoirs are often weakly consolidated making them liable to sand intrusion. During upstream petroleum production operations, crude oil and sand eroded from formation zones are often transported as a mixture through horizontal pipes up to the well heads and between well heads and flow stations. The sand transported through the pipes poses serious problems ranging from blockage, corrosion, abrasion, and reduction in pipe efficiency to loss of pipe integrity. A mathematical description of the transport process of crude oil and sand in a horizontal pipe is presented in this paper. The model used to obtain the mathematical description is the modified form of Doan et al. (1996 and 2000) models. Based on the necessity to introduce a sand deposit concentration term in the mass conservation equation, an additional equation for solid phase was derived. Difference formulae were generated having applied Fick’s equation for diffusion to the mass conservation equations since diffusion is one of the transport mechanisms. Mass and volume flow rates of oil were estimated. The new model, when tested with field data, gave 85% accuracy at the pipe inlet and 97% accuracy at the exit of the pipe.