In recent years, microalgae have been considered in many countries as a fast-growing raw material for the production of biomass (biofuel).

However, it has now been shown that important, higher-value components can also be extracted from microalgae for applications in food supplements (omega 3, etc.) and other pharmaceutical and medical areas.

But uncontaminated raw materials of consistent quality are necessary for these products. Open waters do not offer ideal conditions for this, which is why microalgae are increasingly being grown in closed aquaculture systems.

Photosynthesis is the microalgae’s growth engine and to provide the necessary light, photo-bioreactors have been developed that offer the microalgae an ideal environment conducive to growth.

Since microalgae live in water, photo-bioreactors are water-holding containers whose walls are translucent.

In most cases, the most physically suitable tube design is used.

ATHEX supplies acrylic glass (PMMA) tubes for such photo bioreactors.
Our highly transparent tubes have many technical and economic advantages:

  • PMMA tubes can be manufactured in a wide range of diameters from Ø30 mm to Ø500 mm and lengths of up to 10 m and more
  • The specific weight of PMMA is lower than that of glass by a factor of 1.9 (a tube with a diameter of 300 mm and a wall thickness of 5 mm weighs 10.33 kg/m in glass, but only 5.52 kg in PMMA)
  • PMMA has a high light transmission of approx. 92%
  • PMMA is highly UV-resistant without additional coatings
  • PMMA is approved for contact with food
  • PMMA is resistant to many chemical cleaning agents and to salt water
  • Experience shows that the surface of PMMA is less susceptible to biofouling
  • Tubes made of PMMA are cost-effective
  • No coupling pieces are required up to a height of 10 m

Vertically installed bioreactors require significantly less space and can produce large quantities of algae biomass cost-effectively using the energy-efficient Airlift process. However, the increasing pressure on the tube wall as the water column rises must be taken into account. ATHEX has developed a patented method to regulate the wall thickness of a tube. The wall thickness is adjusted along the tube according to the static loads resulting from the internal pressure. The internal pressure is highest in the lower part of the water column and decreases in a straight line moving up the tube.

The ATHEX process allows the thickness of the tube wall to be adapted to this decreasing pressure load, allowing material savings of up to 25% while maintaining static integrity. In addition to a significantly better environmental balance, this results in clear cost advantages due to reduced material costs and easier assembly due to the lower weight.

In recent years, ATHEX has acquired extensive manufacturing expertise through the supply of acrylic tubes for bioreactors and also has the appropriate equipment to produce the tubes.

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