Co-composting of oil-based drilling cuttings by bagasse

The feasibility of using a locally abundant bulking material (sugarcane bagasse) in Khuzestan province, Iran, to remove petroleum hydrocarbons from oil-based drill cuttings (OBDCs), using composting process, was investigated. OBDCs were collected from the discharge point of a drilling rig and bagasse was collected from a sugarcane agro-industry near Ahwaz. Experiments were performed in the dark and at room temperature, using different bagasse to OBDCs ratios. Degradation extent and kinetics of total petroleum hydrocarbons (TPHs) and poly aromatic hydrocarbons (PAHs), as well as dehydrogenase and urease enzymes activities and number of heterotroph bacteria during the co-composting of OBDCs and bagasse were studied and measured. Highest PAHs and TPH removals were observed when OBDCs were composted with 15% bagasse. After 70 days of incubation, PAHs and TPH were removed up to 24.8% and 67.5%, respectively. Studying the enzymes activities and number of heterotrophs with TPH and PAHs concentrations over time suggests that biodegradation is the main mechanism in the degradation process. The first-order kinetic model was fitted to the TPH and PAHs degradation data and contaminants half-lives were estimated to be in the range of 40-80 and 170-240 days respectively. DT₉₀ values for TPH and PAHs were in the range of 120-260 and 560-1260 days, depending on the bagasse content.