Bioremediation of heavy oily sludge: a microcosms study

Area of Science:

• Environmental Science
• Petroleum Engineering
• Microbiology

Background:

• Oily sludge is a challenging petroleum industry residue, characterized by sand, water, metals, and high hydrocarbon content.
• Heavy oily sludge from Colombian crude oil exhibits high density and viscosity, complicating remediation efforts.
• This study focuses on the bioremediation of such recalcitrant waste generated from heavy oil processing.

Purpose of the Study:

• To evaluate the effectiveness of various bioremediation strategies for heavy oily sludge.
• To assess the biodegradation of total petroleum hydrocarbons (TPH) using biostimulation, surfactants, and bioaugmentation.
• To determine if these methods can achieve regulatory requirements for sludge treatment.

Main Methods:

• Isolation of hydrocarbon-degrading bacteria capable of growth on various hydrocarbons.
• Implementation of bioremediation microcosms with biostimulation (bulking agents, nutrients), the surfactant Tween 80, and bioaugmentation.
• Monitoring of TPH degradation using gravimetric analysis and gas chromatography (GC).

Main Results:

• TPH removal across all tested bioremediation treatments ranged from 2% to 67%.
• The addition of microbial consortiums, amendments, or surfactants did not significantly enhance degradation rates within the study's parameters.
• Bioremediation alone proved insufficient to meet regulatory standards for heavy oily sludge treatment.

Conclusions:

• Bioremediation of heavy oily sludge is challenging and may not achieve desired degradation rates alone.
• The recalcitrant nature of this sludge necessitates further investigation into combined treatment approaches.
• Physicochemical treatments may be required in conjunction with bioremediation for effective sludge management.