The U-Loop Fermentor


The fermentor and its design are the most important aspects of the U-Loop production process.

  1. 1

    Degassing unit

  2. 2

    Continual harvest of biomass

  3. 3

    CO2 outlet

  4. 4

    Nozzle pump

  5. 5

    Injections of medium

  6. 6

    Propeller pump (for moving the fluid through the loop)

  7. 7


  8. 8

    Static mixers

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In traditional stirred fermentors there are problems with achieving sufficiently small bubbles (large surface area of the gas), and there is a large energy waste due to inefficient stirring of the bulk liquid. Furthermore, there are problems with cooling when upscaling.

UniProtein® is produced in a continuous fermentation process. A U-Loop fermentor with static mixers is used. The U-Loop fermentor gives a high utilization of the gases, which are carried through the loop by the liquid flow in almost plug-flow mode. The gases are introduced at the start of the loop and stay in well-mixed contact with the liquid until they are separated in the headspace (see below) at the end of the loop.

The fermentor that is to be used in UniProtein® production is based on a patented U-Loop fermentor design developed in cooperation with DTU.

A 20 m3 and a 50 m3 Nozzle U-Loop fermentor were built and tested by scientists at DTU. The Nozzle U-Loop design makes it possible to obtain a fermentation process that runs optimally with the highest possible product output (larger surface area) in the shortest possible time, i.e. 4 kg/m3/h against 1.8 kg/m3/h for traditional fermentors. There is about 30% energy saving in the Nozzle U-Loop fermentor. In addition, there is no need for mechanical stirring in the U-Loop fermentor.

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