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15 Modernisation
The extraction of alginates
Eztennañ an alginat
On average, it takes 35 to 40 tonnes of brown seaweed to produce 1 tonne of alginates.
In Brittany, the factories use different local species depending on the harvesting periods:
- Laminaria digitata, from May to September.
- Laminaria hyperborea, from February to April and from September to November.
- Ascophyllum nodosum, from September to May.
- Fucus serratus and vesiculosus, from June to October.
Kelp accounts for more than 90% of the seaweed processed. Depending on the species, the processing conditions vary, but the main production stages remain the same.
The alginates, in powder form, are shipped all over the world. The by-products of extraction are also put to use: the sludge is redistributed to local farmers as soil amendments, and the other by-products are turned into biomaterials.