Biosurfactants in the remediation of petroleum-contaminated soils: Mechanisms and applications

Abstract

Petroleum contamination of soils persists despite decades of remediation research. Growing evidence positions biosurfactants as practical tools that align clean-up with soil health. This review synthesizes recent laboratory, pilot, and field studies on rhamnolipids, sophorolipids, trehalose lipids, and lipopeptides. Core actions include reduction of surface and interfacial tension, micelle formation, emulsification of hydrocarbons, and desorption from soil particles. These processes increase bioavailability for indigenous degraders and accelerate loss of persistent fractions. Reported co-benefits include improved infiltration in hydrophobic matrices, better chemical balance in saline soils, and shifts in microbial communities that support sustained recovery. Applications span soil washing and in situ delivery, with consistent gains when biosurfactants are integrated with bioaugmentation, phytoremediation, electrokinetics, or engineered biochar. Performance is dose dependent and bounded by a safety window. Excessive loading can stress plants and impair soil biota, which requires stepwise pilots, dose ceilings, and monitoring of biological indicators. Barriers remain in production cost, formulation stability, and supply at scale. Advances in strain engineering, circular feedstocks, and gentler recovery methods are reducing these constraints. Priority needs include standardized protocols, multi-site demonstrations, and evaluation frameworks that track both contaminant removal and soil function. When molecule choice and delivery are matched to site chemistry, biosurfactants can progress from promising additives to cornerstone technologies for sustainable remediation of petroleum-impacted soils.