Aerobic biodegradation of hydrocarbons in oily sludge from petroleum refineries
Description
The stormwater basin at the Murphy Oil USA Inc petroleum refinery in Meraux, Louisiana contained approximately 6000-9000 cubic yards of oily sludge. Oily sludge of this type would be classified hazardous waste by the recently promulgated Toxicity Characteristic Leaching Procedure regulation (Federal Register, March 29, 1990). Land ban regulations (Federal Register, August 17, 1988) would prevent the land disposal of such waste A search of the literature showed that oil and grease and the specific land ban organics (benzene, toluene, ethylbenzene, xylene, naphthalene, phenanthrene, pyrene, anthracene, benzoanthracene, chrysene and benzopyrene) were aerobically biodegradable in landfarms and wastewater treatment systems. Literature also showed that the benzene, toluene, ethylbenzene and xylene would be partially volatilized The objective of the research was to perform a feasibility study to determine if the stormwater sludge was biodegradable and to follow up the feasibility study with a full scale operation to determine degradation rates of the land ban organics. A final objective was to determine if land ban standards could be met due to aerobic biodegradation A 100' x 120' x 9' reactor was built in the stormwater basin using two sheetpile walls. Six 20 hp aerators were used to mix and aerate the reactor. Mixed liquor samples were caught every other week and analyzed for levels of solids and organics. First order reaction rates were calculated for hydrocarbon oil and grease and the land ban organics Both the feasibility study and the full scale reactor operations demonstrated that the oil and grease and land ban organics were biodegradable. First order oil and grease degradation rates of 0.0135 - 0.0160 days$\sp{-1}$ were measured. Total BTEX levels in the sludge was decreased from 193.6 mg/kg to 1.3 mg/kg. Total polynuclear aromatic hydrocarbons were reduced from 2710 mg/kg to 0.62 mg/kg. Land ban standards were not met in the first phase, which operated at an average temperature of 77$\sp\circ$F, but were met in the second phase, which operated at an average temperature of 104$\sp\circ$F