A combination of solvent extraction and freeze thaw for oil recovery from petroleum refinery wastewater treatment pond sludge

CATEGORY: WASTEWATER TREATMENT 
A combination of solvent extraction and freeze thaw for oil recovery from petroleum refinery wastewater treatment pond sludge

Type	Journal Article
Author	Guangji Hu
Author	Jianbing Li
URL	http://www.sciencedirect.com/science/article/pii/S0304389414008498
Volume	283
Pages	832-840
Publication	Journal of Hazardous Materials
Date	February 11, 2015
Abstract	Researchers studied a combination of solvent extraction and freeze thaw for recovery of oil from high-moisture petroleum refinery wastewater treatment pond sludge. Five solvents, including cyclohexane (CHX), dichloromethane (DCM), methyl ethyl ketone (MEK), ethyl acetate (EA), and 2-propanol (2-Pro) were studied. They observed that these solvents, with the exception of 2-Pro, exhibited a promising oil recovery rate of approximately 40%. However, the recycling of DCM solvent after oil extraction was quite low. Three solvents (CHX, MEK and EA) were then selected for examining the effect of freeze/thaw treatment on improving the quality of recovered oil. This treatment increased the total petroleum hydrocarbon (TPH) content in recovered oil from about 40% to 60% for both MEK and EA extractions. However, little effect was observed for CHX extraction. While the solid residue after oil recovery had a significantly decreased TPH content, researchers noted a high concentration of heavy metals, suggesting that this residue may require proper management. In general, the combination of solvent extraction with freeze/thaw appears to be effective for high-moisture oily hazardous waste treatment.