The Alfa Laval Sigma series of olive oil decanter centrifuges for two-phase separation help you improve quality and increase yield. Maximize oil recovery throughout the flow range whilst minimizing environmental costs. These compact, reliable and efficient olive oil decanter units are ideal for clarification, extraction, sludge watering and classification on the first and second extraction (remilling).

Olive Oil Sigma 9 640x360

Our customers:

Sociedad Agricola Ouro Vegetal, Portugal

The Alfa Laval Sigma 8 decanter was installed for this season, and up to now it has already processed 4000 tonnes of olives. Our first impression of the Sigma 8 was extraordinary, both in terms of yield and separation efficiency.
SAOV has been partnered with Alfa Laval since we started in 2004. Our relationship with Alfa Laval is very close and extremely good. It is familiar, based on mutual help, information sharing, companionship and reciprocal trust.
From the start, all Alfa Laval decanters we have tested have been efficient, reliable and long-lasting. In fact, they have been working for a long time, showing the long-lasting and long-term reliability of the equipment.

- Rita Marques, Food Quality Manager, SAOV

De Carlo, Italy

We have been using Alfa Laval equipment for the last 50 years, because Alfa Laval is always focused on improving the quality and efficiency of their products.
This has allowed us, on the one hand, to improve the quality of our olive oil. And on the other hand, we have been able to optimize costs, reducing the consumption of water, improving temperature control, and improving the flexibility and adaptability of the decanter for the product.
Sigma 6 gave us two advantages: the first is that we save on energy needed to heat up the water, and we also eliminated the need to spread black water in the field.
As we see with Sigma 6, they can help us to simplify mill operations and, where it is possible, increase the quality of oil we produce.

- Francesco De Carlo, Quality and Production Manager of De Carlo Olive Oil. 

Fabricadouro, Portugal

The results have been great. We get the yield we were looking for along with maximum quality.”
The relationship between Fabricadouro and Alfa Laval is really good. Alfa Laval always solves our problems. Their people are very close and available to us during the season. I would recommend Alfa Laval to anybody. They will be well served by buying Alfa Laval equipment.”

- Alvaro Vega, Owner of Fabricadouro

Alfa Laval First in olive oil

A full spectrum of olive oil production market needs

With the introduction of  the Alfa Laval Sigma 6 and Sigma 8 to supplement the existing Sigma 9 and Sigma 10 models, Alfa Laval now covers the full spectrum of market needs. Whether you are a small-scale olive oil miller or an industrial-scale producer, Alfa Laval’s passionate experts can help you increase capacity and profitability. Our proven olive oil extraction machines, alongside industry knowhow and an extensive global service and support network, promise reliable production throughout every season.



Olive farm 1920x480

First in production


Sigma decanter centrifuge design benefits:

  • Feed zone position that maximizes the time the oil spends inside the unit, and how much oil is extracted
  • Special conveyor design that improves solids transport and maximizes oil recovery
  • Special flights to prevent turbulence as the oil moves towards the liquid outlet, to optimize yield and oil clarification
  • Surface level of olive oil outlets ensure minimal heating of the oil during separation, helping protect oil quality
  • Special bowl design with easy oil discharge minimizes the quantity of oil held inside the bowl
  • Fully protected feed zone, featuring a special design that improves resistance to wear
  • 360° solids discharge outlets made of tungsten carbide, which provides exceptional protection against wear and keeps power consumption to a minimum
  • Conveyor fitted with tungsten carbide tiles (standard on Sigma 8, 9 and 10; optional on Sigma 6) to provide wear protection that significantly reduces maintenance costs
  • Conveyor parts subject to high wear are easy to replace
  • Easy serviceability
  • Cover is equipped with hinges and springs to make it easy and safe to open, clean and inspect the decanter



Decanter centrifuges in the Sigma range are equipped with a variable frequency drive (VFD) and are available with control solutions to comply with your specific operating requirements.


Sigma decanter centrifuges can also be fitted with IoT equipment, to provide users and decision-makers with a wide range of operating data, whether onsite or off.

  • Remote support enables your service provider to provide remote troubleshooting to help ensure maximum processing uptime and keep your Sigma unit or units running throughout the hectic olive processing season
  • Remote monitoring ensures greater peace of mind. Access Alfa Laval´s connectivity portal to remotely monitor your decanter centrifuge and receive any appropriate alarm notifications

How it works

Sigma olive oil decanter centrifuge illustration
  1. Gearbox
  2. Wet husk outlet
  3. Conical end
  4. Screw conveyor
  5. Bowl
  6. Olive Oil outlet
  7. Feed tube
  8. Feed inlet
  9. Oil discharge ports

Sigma olive oil decanter centrifuge operating principles

The Sigma olive oil decanter centrifuge design makes sure the incoming paste is effectively separated into oil and wet solids.

The olive paste is fed into the bowl of the unit through a stationary inlet tube, and is then smoothly accelerated by an inlet rotor. Separation takes place in a horizontal cylindrical bowl equipped with a screw conveyor. Centrifugal force makes the oil accumulate at the liquid surface, while the solids settle on the inner wall of the bowl, surrounded by the water separated out of the feed stream.

The conveyor rotates at a slightly different speed than the bowl and moves the solids to the discharge ports in the conical end. Olive oil extraction takes place along the entire length of the cylindrical part of the bowl. The oil is returned to the large end for discharge, and then passes into collecting tanks via a filter.


The Alfa Laval Sigma range of olive oil decanter centrifuge:


Sigma 6

For small-scale olive oil producers

Alfa Laval olive oil decanter centrifuge for small-scale production

Sigma 8

For industrial-scale olive oil producers

Alfa Laval olive oil decanter centrifuge for industrial-scale production

Sigma 9

For industrial-scale olive oil producers

Olive Oil Sigma 9 640x360

Sigma 10

For industrial-scale olive oil producers

Olive oil decanter centrifuge Sigma 10