Radical-mediated synergistic remediation of crude oil contamination by nutrient-enriched indigenous microbial consortium from multiple culture media

Abstract

To improve the low remediation efficiency of single microbial strains for crude oil-contaminated wastewater, indigenous microbial consortium was enriched using four media (TSB, PDB, YPD, and CPD). A ternary system integrating microbes, surfactants, and chemical oxidation was constructed to enhance remediation performance. The enriched complex consortium achieved 47% crude oil removal within seven days at 0.5–1 g·L−1, but their performance declined sharply at concentrations above 2 g·L−1. EPR tests verified different reactive oxygen species generation in two surfactant-coupled oxidation systems: the AES–PS system produced multiple radicals (SO4·-, ·OH, ·O2-,1O2) for synergistic solubilization and oxidation, whereas the Tween 80 system only yielded hydroxyl radicals with pollutant solubilization dominating the diffusion process. At an initial crude oil concentration of 0.5 g·L−1, the AES–PS system achieved a high crude oil removal efficiency of 87.8% within 3 h. For high crude oil loading (2–4 g·L−1), the ternary system outperformed single microbial remediation and chemical oxidation by 30% and 10%, respectively, maintaining a stable removal rate of 84% with 50% reduced oxidant dosage. Mechanistically, surfactant–oxidation pretreatment transformed recalcitrant crude oil into biodegradable intermediates. The synergistic interplay among the three modules promoted microbial metabolism, functional gene expression, and crude oil bioavailability.