French potato chip manufacturer makes the most of leftovers

Biogas plant builder Weltec Biopower, in collaboration with Weltec France, has built a biomethane plant for ALTHO, a manufacturer of potato chips in Saint-Gérand, Brittany. The plant allows the company to generate around 200 standard m³/h of biomethane from production waste and sludge of its own wastewater treatment plant.

ALTHO holds over a third of the market share with its chips brand, Bret’s. Producing the chips yields 22,000 tonnes of leftovers and sludge a year, with the potato and starch leftovers, alongside other production waste, making up half the substrate. The rest comprises the sludge from the washing process.

The solid and liquid substrates are first mashed and shredded in the MULTIMix input system. After this pre-processing, the mixture is fed into the stainless steel digester. A post-digester is the last step in the material cycle and the digestate is sold to local farmers, who use it as fertiliser.

Image credit: Weltec ALTHO.

When transforming the biogas into biomethane, Weltec Biopower conditions the biogas by integrating the membrane technology in a compact container solution. In the container, the raw gas passes through special membranes that separate it from carbon dioxide, steam and other components. This three-stage separation reduces the methane slip to less than 0.5%.

The upstream compression provides another benefit, as it provides the right pressure for the methane to be fed into the natural gas grid without further compression. The separation occurs at ambient temperature, without using chemicals. In this way, 400 standard m³/h of raw biogas yield about 200 standard m³/h of processed biomethane.

“Owing to the durable membranes, the plant availability is high and the maintenance overhead is low. In Saint-Gérand, we ensure uninterrupted gas feed-in with our custom-developed LoMOS PLC,” said Alain Priser, who is responsible for Weltec’s business in France.

With this equipment, ALTHO is able to focus on its core business and make efficient use of accumulating leftovers.

Top image credit: ©stock.adobe.com/au/colnihko