Oil Sludge Treatment: Reduction, Recyclable and Harmless

Oil sludge is solid waste generated during oil production and processing. It contains a variety of organic pollutants and heavy metal pollutants and has strong biological toxicity. As a result, oil sludge treatment is critical for minimizing environmental harm and recovering valuable resources. At present, the oil sludge treatment technology has developed significantly, forming different treatment and disposal technologies. According to the difference in treatment objectives, oil sludge treatment can be summarized and classified from three directions: reduction, recyclable and harmless treatment.

Reduction Treatment

Oil sludge reduction technology is to reduce the volume of oily sludge by dehydration, sludge concentration and other methods. The main purpose of reduction treatment is to reduce the water content of oil sludge and reduce the volume of sludge, so as to reduce the difficulty and cost of subsequent treatment of oil sludge. The technology can be divided into sludge concentration technology and sludge dewatering technology.

Resource Recyclable Treatment

Resource recyclable treatment can process and reuse the valuable substances in oil sludge, which is the best way to treat oily sludge. According to the different treatment temperatures, the resource recovery treatment methods of oily sludge can be divided into low-temperature freezing method, normal temperature separation method and high temperature treatment method.

NO.1 Low-temperature Treatment

NO.2 Normal-temperature Treatment

NO.3 High-temperature Treatment

Freezing and Thawing Treatment

The low-temperature freezing method and the freezing/thawing method utilize the large difference in the freezing point of water and oil. After part of the water phase solidifies, its volume expands, breaking the constraints of the oil phase. While the solidified water droplets gather, they create cracks large enough for the unsolidified water droplets to penetrate and gather. After thawing, the oil and water are separated, and the oil phase can then be recycled.

Normal-temperature Treatment

Centrifugation treatment: Mechanical centrifugation mainly uses the centrifugal force generated by the high-speed rotation of the centrifugal equipment to separate the components of different densities such as crude oil, water and solid impurities in the oil sludge.

Solvent extraction treatment: Solvent extraction is a technology that involves mixing oil sludge with an extraction solvent in a specific ratio. This process removes solid particles, water, and other impurities from the mixture, followed by distillation to separate and recover the crude oil from the extractant.

Thermal washing treatment: The thermal washing method mainly adds an appropriate amount of hot water and chemical reagents to the oil sludge. Through the action of chemical reagents, the properties of the oil-liquid phase and the oil-sludge interface in the oil sludge are changed, and the crude oil is washed off the sludge surface.

Froth flotation treatment: The froth flotation method uses bubbles to carry oil droplets to float and collect them, achieving sludge separation and crude oil recovery. The process includes demulsification, bubble attachment, flotation and oil drop scraping.

High-temperature Treatment

Pyrolysis technology: Pyrolysis technology heats oil sludge under high-temperature conditions to separate oil from organic matter. This process breaks down the oil sludge into solid residue and pyrolysis gas, enabling resource utilization.

Microwave radiation technology: Microwave radiation technology achieves dehydration, demulsification and separation of oil sludge through rapid and uniform heating, promoting efficient recycling of oil, water and residue.

High-temperature gasification technology: It is an emerging method for thermal treatment of oil sludge. Using water vapor, CO2 and other gasification agent, the organic matter in the oil sludge is converted into combustible gases such as CO and H2, achieving clean utilization of energy and greatly improving energy recovery efficiency.

Harmless Treatment