Bioremediation potential assessment of oil-degrading bacterial consortium prepared from local bacterial strains and its survival using different porous carriers

Abstract

Oil sludge contains high levels of heavy chain petroleum hydrocarbons and heavy metals that hinder its biodegradation. Hence for successful remediation, selecting potent isolates and construction of efficient bacterial consortium is inevitable. The aim was to achieve bacterial consortium with the ability to tolerate harsh environment of oil sludge and degrade different hydrocarbon fractions of it. For this purpose, native oil-degrading and biosurfactant-producing bacteria were screened from oil tanks bottom sludge and were evaluated for their salt and heavy metal tolerance. Also, oil-degrading potentials of the isolates as well as their consortium were assessed through GC-FID analysis under both static and shaking conditions. The potential of sugarcane vinasse as a low-cost culture medium for large scale culture of the isolates as well as their immobilization and long-term viability on porous carriers including diatomaceous earth, sugarcane bagasse, and biochar were also investigated. The results showed that A. lactucae strain Ib-30 had the highest hydrocarbon degradation (~ 77%) and high level metal resistance. The oil-degrading efficiency of bacterial consortium was lower than that of individual isolates. S. warneri strain Ae1-30 was identified as the most halotolerant and metal-resistant isolate. Vinasse supported the growth of all strains, with C. hisashii strain T1-50 showing the highest proliferation rate. Sugarcane bagasse outperformed other carriers in maintaining bacterial viability over 14 months. Overall, these findings demonstrate the feasibility of scalable, sustainable bioremediation of oil sludge using potent indigenous bacterial resources and effective bio-carriers, offering a promising solution for industrial waste management.