CPI is one kind of high efficient oil-water gravity separator, now is widely used in oily wastewater treatment to remove bulk oil from water.

Gravity separation is the most straightforward method of wastewater treatment and is, therefore, utilized widely in industry for separation of settling and/or floatable impurities from a carrier liquid.

An enlarged separating surface can be achieved by placing various smaller planes on top of each other in the tank. If these planes are subsequently inclined in a tilted position, material separated between the plates is removed by the gravitational force. This is the principle on which the CPI corrugated plate pack is based.

In this plate pack the planes as referred to have been constructed in the shape of corrugated plates. They promote both the coalescence of the intercepted oil particles and, at the same time, their transfer through the plate pack.

If settleable material is present in the liquid, such material is collected and concentrated in the troughs of the corrugations so that it will slide down in the plate pack smoothly and easily.

Very small separating diameters can be obtained in the CPI system, because the disturbing factors, such as eddies and turbulences, which adversely affect large conventional separating tanks (e.g. API’s), are eliminated in the CPI.