CPI Wastewater Treatment Equipment | Oil-Water Separation Solutions

CPI wastewater treatment equipment is a physical oil-water separation unit used to remove free oil, floating oil and part of suspended solids from industrial wastewater. CPI means Corrugated Plate Interceptor. It is commonly used as a pretreatment device before dissolved air flotation, biological treatment, filtration, membrane systems or discharge treatment.

The working principle is based on gravity separation and coalescence. Oily wastewater enters the CPI separator through an inlet distribution zone. Inside the equipment, wastewater flows slowly through multiple inclined corrugated plates. Oil droplets rise because oil is lighter than water, while heavier particles settle downward. The corrugated plates shorten the rising distance of oil droplets and help small oil droplets coalesce into larger droplets. These larger droplets float to the surface and are collected by an oil skimming or oil discharge system. Settled sludge is collected at the bottom and discharged regularly.

A typical CPI pretreatment process is:

A complete CPI oil-water separation system may include an inlet chamber, flow distribution device, corrugated plate pack, oil collection zone, oil skimmer or oil discharge pipe, sludge hopper, sludge discharge valve, water outlet chamber, access cover, pipelines, valves and optional control system. Depending on project requirements, the equipment can be made of carbon steel with anti-corrosion coating, stainless steel, FRP or other suitable materials.

For B2B buyers, selecting CPI equipment should not be based only on water flow. Important parameters include influent flow rate, peak flow, free oil concentration, oil droplet size, suspended solids concentration, wastewater temperature, pH, viscosity, density difference between oil and water, required effluent oil content, available installation space and downstream treatment process. If the wastewater contains stable emulsified oil, dissolved organic pollutants or surfactants, CPI separation alone may not achieve the final treatment target. In such cases, chemical demulsification, coagulation, DAF, filtration or biological treatment may be required.

CPI separators are especially useful where free oil removal is required before further treatment. By reducing oil load in advance, they can help protect downstream pumps, pipes, filters, membranes and biological systems. In many industrial wastewater projects, CPI equipment is installed before DAF units to reduce floating oil and improve overall treatment stability.

Maintenance is also important for long-term operation. Operators should regularly remove collected oil, discharge settled sludge, inspect plate packs, clean blocked channels and check valves and pipelines. If sludge or grease accumulates inside the plate area, separation efficiency may decrease.

Qingdao Jinwantong provides customized CPI wastewater treatment equipment and supporting systems for industrial oily wastewater projects. Buyers can send flow rate, oil concentration, TSS level, water quality data, site layout, material preference and treatment target for technical selection and quotation.