Full-scale bioremediation of petroleum-contaminated soils via integration of co-composting

Purpose: Pollution from oil operations; exploration, drilling, transfer, transport, refinery and distribution reduce soil quality, and results in the removal of a large amount of soil from annual utilization cycles. Soil quality is an essential asset of sustainable development and is negatively affected by erosion and anthropogenic activity. Co-composting is a biological technique used in the bioremediation of soils, which was investigated in this study. Materials and methods: This study focused on the remediation of 1200 m3 of saline contaminated soil from an oil-polluted operational area in Iran. The initial total petroleum hydrocarbon (TPH) content of the soil was between 6.9 and 17.1 g kg−1 and was contaminated with heavy oil. Initial water repellency of the soil was between 1500 and 12,500 S. The remediation procedure commenced with trials in which organic waste of a local sugarcane sugar factory, mixed urea, sugar, and compost mixtures was added to contaminated soils. Results: After irrigation and aeration of piles of organic materials and soil over 3 months of operation, the TPH reduced from 4.86, 6.52, and 9.89 to 0.068, 0.080, and 0.109 g kg−1, in the moderately, highly, and very highly polluted soil piles respectively. At the end of the remediation project, following gas chromatography analysis of contaminant content, and in accordance with governmental authorities, recovered soils were added to the surrounding environment to the support growth of the natural ecosystem. Conclusion: Soil recovery and remediation utilizing valorization and complimentary local industries have a transferable quality that may be adapted to additional vulnerable sites in droughted and variable edaphic and climatic conditions.