A comparative life cycle analysis of bioremediation approaches for old-aged petroleum pollution in hypersaline soil

Soil oil pollution is a major environmental issue, especially in oil-producing nations, as it threatens the health of plants, animals, and humans. While bioremediation has been extensively utilized as a cost-effective method for restoring oil-contaminated soil, its environmental impact has garnered relatively little attention. Researchers often concentrate on reducing pollutant concentrations below permissible limits to restore soil quality. In a project conducted in Khuzestan province, various bioremediation methods were implemented over 60 days to address old-aged petroleum pollution in hypersaline soil. This study focused on three efficient bioremediation methods to assess their environmental impacts using Life Cycle Assessment (LCA) at the laboratory scale and to bridge a critical knowledge gap regarding the complex interaction between bioremediation strategies and the ecosystem. Contrary to prevailing belief, the findings revealed that some bioremediation methods could have negative environmental consequences. Inorganic nutrients, used as biostimulation agents for the native microbial community in contaminated soil, were identified as potentially harmful. The use of inorganic nutrients in the bioremediation of one ton of soil resulted in damage of 2 × 10^-4 DALY to human health, 67.5 PDF∗m²∗yr to ecosystem quality, 84.2 kg CO₂ eq. to climate change, and 780.8 MJ to the resource. However, the organic waste utilized in the restoration of oil-contaminated soil substantially reduced the average environmental footprint score, achieving up to 37 mPt. The combination of organic wastes with specific bacteria led to a powerful and eco-friendly bioremediation process.