Background and purpose: Toxicity, high levels and complex nature of petroleum hydrocarbons in drill cutting can endanger human health since many of these compounds are among carcinogenic hazardous waste components. This study aimed at comparing the effect of compost and vermincompost processes in removing petroleum hydrocarbons from drill cutting located in Ahvaz oil field with sewage sludge.

Materials and methods: An experimental study was performed in which the effect of a 1:1 mixture of biological sludge with drill cutting contaminated with TPH, along with sawdust and horticultural waste was examined for composting and vermicomposting. The degradation time was about 60 days in pilot chamber. The TPH, carbon to nitrogen ratio, pH, EC, volatile solids, and temperature levels were measured. To ensure the integrity and accuracy of measurements testing was done in 3 iterations.

Results: The mean TPH level in the drill cutting in Ahvaz oil field was 42.004 g/kg that reduced to 11.31 and 18.77 g/kg during two months treatment by vermicomposting and composting with biological sludge, respectively. The removal efficiency of TPH in drill cutting in vermicompost pilot was 73.06% while it was 55.30%. in compost pilot.

Conclusion: In this study, vermicompost process to be highly capable of removing TPH from oil-based drill cutting.