Industrial CPI Filter for Oil-Water Separation | Jinwantong

An industrial CPI filter is a compact oil-water separation device used for pretreating oily industrial wastewater. CPI stands for Corrugated Plate Interceptor. Although it is often called a “filter,” its main function is not fine filtration, but gravity-based separation of free oil, floating oil, grease and part of settleable solids.

Industrial wastewater may come from petrochemical plants, machinery workshops, vehicle washing stations, steel mills, power plants, shipyards, food processing factories and other manufacturing facilities. These effluents often contain lubricating oil, cutting oil, floating grease, suspended solids and process residues. If free oil is not removed at the pretreatment stage, it may reduce DAF efficiency, block filters, foul membranes, affect biological treatment and increase maintenance costs.

The working principle of a CPI oil-water separator is based on density difference, laminar flow and coalescence. Wastewater enters the inlet distribution chamber, where flow is slowed and evenly distributed. It then passes through a series of inclined corrugated plates. Since oil is lighter than water, free oil droplets rise along the plate surface. The corrugated plate structure shortens the rising distance and helps smaller droplets merge into larger oil droplets. These larger droplets float to the oil collection zone and are discharged through an oil outlet or skimming device. Heavier solids settle into the sludge hopper and are removed through the sludge discharge system.

A typical treatment process is:

A complete industrial CPI filter system may include an inlet chamber, flow distribution device, corrugated plate pack, separation tank, oil collection area, oil skimmer or oil discharge pipe, sludge hopper, sludge discharge valve, outlet chamber, inspection cover, pipelines, valves and optional control components. According to wastewater composition and site conditions, the equipment can be manufactured from carbon steel with anti-corrosion coating, stainless steel, FRP or other suitable materials.

For correct selection, buyers should provide average flow rate, peak flow, oil concentration, oil droplet size if available, TSS, pH range, wastewater temperature, viscosity, corrosiveness, required outlet oil content, installation space and downstream process. These parameters affect retention time, plate configuration, tank volume, material choice and sludge discharge design.

It is important to understand the application boundary. CPI filters are effective for free oil and separable oil droplets, but they cannot directly remove stable emulsified oil, dissolved organics or soluble chemicals. If wastewater contains surfactants, emulsified oil or complex pollutants, the CPI system may need to work with demulsification, coagulation, DAF, filtration, biological treatment or membrane treatment.

Qingdao Jinwantong provides customized industrial CPI filters and supporting wastewater treatment equipment. Buyers can send wastewater data, flow rate, oil content, TSS, pH, site layout and treatment target for model selection and quotation.