Enhances separation by placing wastewater under high acceleration. They have high energy and maintenance requirements. Can produce effluent concentrations down to 70 ppm. Best solution for removing emulsified oil. There are two methods.
Coalescence causes the oil to rise to the surface by neutralizing the droplets' surface charge.
Sensitive to changes in the wastewater. Precipitation causes the droplets to attach themselves to floc that forms from the treatment chemicals. The floc settles to the bottom, taking the oil with them. More complex of the two, but not sensitive to wastewater characteristics. Very little data is available on wastewater generated by small quantity generator operations.