Cyclonic separation of oil and water from oily wastewater
Oil-water separation is an important prerequisite for the efficient utilization and disposal of oily wastewater. Traditional oily wastewater treatment technologies have limitations in the removal of oil and suspended solids due to their insufficient separation or the high cost of the operational processes. In light of these disadvantages, the cyclonic separation process has become an increasingly attractive technology to treat oily wastewater because of its relatively low cost and advantageous capture efficiency.
Cyclonic separation is a physical oil-water separation process based on the centrifugal forces generated by spinning a volume of liquid in a cylindrical container. Depending on the volume of liquid and the speed of rotation, a centripetal force is created that causes suspended particles to gravitate towards the centre of the tank, where they are then removed. As the particles reach the centre, they are transported upward and out of the container along a wall of solid material known as the cyclonic separator.
This approach differs from traditional oil-water separation processes in that it does not require the addition of chemicals or minerals, has no moving parts and does not involve any filtration with a filter medium. The captured suspended particles are removed from the bottom of the separator, with the oil and water either returned to the wastewater stream or collected separately for further treatment and disposal.
Cyclonic separation has several advantages over traditional oil-water separation processes. It has a higher capture efficiency for suspended particles compared to traditional technologies and can capture solids as small as 1 µm without the use of filter media. It also does not require any chemical or mineral insertion and has a relatively low energy consumption.
Furthermore, the cyclonic separation process requires little maintenance and is relatively easy to operate. As a result, its use as a stand-alone process or as a part of an oil-water separation system is well established in the industry.
Despite the many advantages, there are also some drawbacks to the cyclonic separation process. The process requires a high flow rate to ensure the maximum capture efficiency, which may not be feasible in some installations; and it can only separate oil and water, with no other contaminants being separated. Also, the high speed and pressure of the centrifuge can damage mild steel, so other materials such as stainless steel must be used.
In conclusion, cyclonic separation is an effective method for separating oil and water from oily wastewater. Its advantages include high capture efficiency, low operation and maintenance costs, and no requirement for chemicals or minerals. However, it is not suitable for all wastewater streams, due to its limitations in treating other contaminants and its relatively high flow rate requirements.
