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A decanter centrifuge (also written “centrifuge decanter”, and sometimes called a solid bowl centrifuge) is a continuously operating, process-scale machine that separates solids from a liquid, or separates two liquids, using centrifugal force inside a rotating horizontal bowl. It is industrial equipment, not a benchtop laboratory centrifuge. This page describes the equipment and general principles; it is not operating or safety instruction for a specific machine.
Who uses it: process engineers and operators in food and beverage, life-science fermentation, oils and fats, biofuels, wastewater, mining and recycling, plus pilot-plant teams testing a separation before scaling it up.
What a decanter centrifuge is
A decanter centrifuge spins a slurry so that denser solids are pushed against the bowl wall while the liquid forms an inner layer. Alfa Laval states that the centrifugal force can be up to 4,000 times greater than gravity. Unlike a laboratory tube centrifuge that processes a batch, a decanter is fed continuously and discharges solids and liquid continuously. For the batch laboratory instruments it is often confused with, see what a centrifuge is and RCF versus rpm.
How a decanter centrifuge works
Inside the machine, a cylindrical-plus-conical bowl rotates at high speed. A screw conveyor (the scroll) rotates inside the bowl at a slightly different speed. That speed difference moves the settled solids out of the liquid “pond” and up the conical “beach”, where they leave as a dewatered cake, while clarified liquid overflows over dam plates or weirs at the other end (Alfa Laval; Wikipedia, “Decanter centrifuge”).
- Bowl: the rotating cylindrical and conical shell in which the separation happens.
- Scroll (conveyor): transports settled solids toward the solids outlet.
- Pond depth: set by interchangeable plates or tubes (Alfa Laval) or weir discs (Wikipedia), which controls how the liquid and solids are split.
- Paring disc: a centripetal pump on some designs that removes the clarified liquid under pressure.
- Drive: Alfa Laval describes a variable-frequency drive with torque control that adjusts the differential speed to avoid overload, which reduces wear and energy use.
Types and variants
| Type | What it does | Source |
|---|---|---|
| Two-phase decanter | Separates solids from one liquid phase; the configuration of scale-up testing units such as GEA’s pilotMaster. | GEA; Wikipedia |
| Three-phase decanter (“tricanter”) | Separates solids and two immiscible liquids at once, for example in olive oil, oil sludge and biodiesel processing; the liquid phases are collected separately. | Alfa Laval; Wikipedia |
| Horizontal decanter | The most common industrial arrangement. | Wikipedia |
| Vertical decanter | Single-bearing design; Wikipedia notes higher temperature and pressure capability, higher cost and quieter running than horizontal units. | Wikipedia |
| Pilot-scale decanter | Smaller test unit used to evaluate a separation before choosing a production machine. | GEA |
Differential speed: the main trade-off
The difference between bowl and scroll speed is the setting with the clearest published trade-off. According to Wikipedia (citing Perry’s Chemical Engineers’ Handbook and the Decanter Centrifuge Handbook), a high differential speed gives higher solids throughput with a shorter cake residence time, while a low differential speed gives a clearer liquid.
| Differential speed | Effect | Source |
|---|---|---|
| Higher | More solids throughput, shorter cake residence time | Wikipedia |
| Lower | Clearer liquid (centrate) | Wikipedia |
Specifications that matter
Published figures vary by model, so read a manufacturer’s data sheet rather than a generic range. Wikipedia gives typical operation at roughly 1,000 to 4,000 g and notes that decanters can handle slurries of more than 40% solids by volume, with bowl length-to-diameter ratios of 2, 3 and 4 common. As one concrete example, GEA lists its pilotMaster two-phase test decanter at a bowl speed of 1,000 to 6,500 rpm, a differential speed of 1 to 80 rpm (Hydro Drive option ranges 1 to 15 and 10 to 80 rpm, adjustable in under five minutes), wetted parts in duplex, super duplex or Hastelloy C276, operation up to 130 °C and an optional ATEX version. These are one product’s values, not a standard.
Applications
Alfa Laval lists food and beverage (wine, brewing, olive oil, starch), life science (fermentation and biomass), palm oil, rendering and fish processing, biofuels, wastewater, battery recycling, mining tailings, and pulp and paper.
Decanter versus laboratory centrifuges
A decanter handles continuous, high-volume or high-solids streams; benchtop and floor-standing laboratory centrifuges handle discrete samples in tubes or bottles. For ultra-high-force laboratory separation see ultracentrifugation; for a small clinical example see the microhematocrit centrifuge; for how such instruments fit into lab workflows see equipment in the medical laboratory.
Common mistakes
- Treating “decanter centrifuge” and “centrifuge decanter” as different machines; they are the same equipment.
- Confusing it with the laboratory step of decanting liquid off a pellet, which is manual and not this machine.
- Quoting one model’s speed or temperature figures as typical for the whole class.
FAQ
Is a centrifuge decanter the same as a decanter centrifuge?
Yes. Both phrases refer to the same continuous solid-bowl separator.
What does the scroll do?
It rotates at a different speed from the bowl and conveys settled solids out of the pond and up the conical section to discharge (Alfa Laval).
Can it separate two liquids?
Three-phase versions separate solids plus two immiscible liquids, collecting the liquid phases separately (Alfa Laval; Wikipedia).
Sources (read 2026-11-08)
- Alfa Laval, Decanters: https://www.alfalaval.com/products/separation/centrifugal-separators/decanters/
- GEA, pilotMaster two-phase decanter: https://www.gea.com/en/products/centrifuges-separation/decanter-centrifuge/2-phase-decanter/pilotmaster/
- Wikipedia, Decanter centrifuge (secondary; cites Perry’s Chemical Engineers’ Handbook, 8th ed., and Records and Sutherland, Decanter Centrifuge Handbook, 2001): https://en.wikipedia.org/wiki/Decanter_centrifuge
