Approaches Involved in the Treatment and Disposal of Petroleum Refinery Sludge

The production of voluminous hazardous solid waste by the petroleum refinery industries remains to be one of the biggest environmental concerns. Among the various wastes produced during oilfield exploration, refining, collection, and transportation, petroleum oily sludge (POS) stands out as the predominant solid waste. On average, for every 1000 tons of crude oil processed in the refinery, around five tons of POS are generated. POS is characterized by a complex combination of heavy metals, hydrocarbons, persistent organic compounds, and water/oil emulsions making it a hazardous and toxic substance that cannot be disposed of without proper treatment. Thus, an effective POS treatment technology is essential prior to disposal to reduce the risk of environmental pollution and corrosion. Various conventional treatment technologies are available to treat petroleum sludge such as freezing, thawing, centrifugation, pyrolysis, ultrasonic treatment, surfactant washing, and solvent extraction. After the oil is recovered from the POS, the remaining wastes are disposed of using several methods like biodegradation, oxidation, stabilization/solidification, and incineration. The waste management techniques mainly follow a three-phase approach: (1) utilizing available technologies to reduce POS production, (2) recovery of oil from POS, and (3) disposing of the residual POS after effective treatment. Thus, this chapter encapsulates the different approaches employed in the treatment and disposal of POS resulting from petroleum refinery industries.