AGRICULTURAL WASTE CARRIERS FOR IMMOBILIZED MICROBIAL BIOREMEDIATION OF OIL-CONTAMINATED SOILS: A COMPREHENSIVE REVIEW

Abstract

Petroleum hydrocarbon contamination represents a critical global environmental challenge affecting over 5 million km². Bioremediation using immobilized microbial consortia has emerged as a sustainable alternative to conventional remediation methods. This review examines current advances in immobilization technologies for oil-contaminated soil remediation, with particular focus on agricultural waste carriers including rice husks, buckwheat husks, and other lignocellulosic materials. Immobilized systems demonstrate significantly superior performance compared to free-cell applications, achieving degradation efficiencies of 50-90% versus 20-45% for free cells. Buckwheat husks exhibit exceptional performance with 58.4% TPH degradation and rate constants of 0.0187 d⁻¹, representing 73% enhancement over free-cell systems. This superior performance correlates with high rutin content (28.8 mg/100g) providing antioxidant protection, immobilization efficiency of 92.3%, and favorable moisture retention (55%). Rhodococcus and Dietzia genera demonstrate complementary metabolic capabilities for comprehensive hydrocarbon degradation. Key factors influencing remediation success include carrier porosity, surface area, immobilization efficiency, moisture retention capacity, and biochemical properties including antioxidant content. Despite promising laboratory results, challenges remain in scaling to field applications under extreme environmental conditions. Future research should prioritize optimization of carrier pretreatment, development of stress-tolerant strains, and integration of multi-carrier systems.