DCI™ - Degrémont Circular Interceptor



Degrémont Circular Interceptor (DCI™) for the pre-treatment of oily effluents in Refineries & Petrochemical complexes utilizing gravity separation of insoluble hydrocarbons and suspended matter.

DCI™ Technology

The DCI™ process is a new generation of circular separators for pre-treatment by gravity separation of insoluble hydrocarbons and suspended matter. The treatment of oil refining and petrochemical effluents can be applied over a wide flow range, from a few m3/h to 2000 or 3000 m3/h. Normally, it involves several stages:

  • Pre-treatment of free and emulsified oils and sand by physical separation,
  • Aerobic, biological, purification,
  • Tertiary treatment

The first stage in treating wastewater effluent from refinery and petro-chemical processes influences the effectiveness of the physical-chemical treatment stage and offers protection against accidental pollution. Physical pre-treatment removes most of the free, insoluble hydrocarbons, which form a film on the surface of the water. Likewise, the worst of the suspended solids in the drainage water (sand, catalysts, carbon, etc.) are removed by settling.

The DCI is a cylindrical/conical structure fitted with an automatic scraper to enable the recovery of free-floating oils and to remove bottom sludge. A surface skimming assembly with a scum baffle allows the recovery of free-floating oils in a discharge channel, and ensures that water discharged over a peripheral weir has a reduced oil and scum content. A bottom scraping assembly conveys the sludge towards the center of the unit. The circular design of the tank and the slope of the floor enhance the recovery of sludge in the center of the unit. The bottom sludge draw-off is therefore carried out by pumping from a single location of the tank. The surface skimming and bottom scraper assembly is powered by a central drive unit.

The DCI is a superior alternative to existing systems on the market, such as:

  • Longitudinal separators, which meet API standards but may generate odors and have mixed success with bottom sludge extraction
  • Corrugated Plate Interceptor (CPI) systems and parallel plate separators, which are subject to fouling by waxy products and which do not handle bottom sludge effectively.


Product sheet

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Main Advantages

  • Construction more economical than rectangular API and CPI
  • Optimized Retention Time: Approximately 40 minutes
  • Reduced odor emissions
  • Improved performance with superior scraping, greater water height, bottom sludge thickening facilitated and easily removed


Applications are similar to primary API separators / oil separators, but at a lower cost and with a reduced footprint: removal of free-
floating oils and suspended matter in primary effluents from
refineries, petrochemical processes and produced water.