Undisclosed · Seed · Cleantech · Horw, Switzerland
Swiss carbon-removal startup Arrhenius has closed an undisclosed seed round with backing from CTA AG, Young Ventures AG and angel investors Thomas Krumbeck and Ralf Wildenhues. According to the company's funding announcement, the capital will support a 500 m² pilot plant that combines carbon removal with wastewater treatment, followed by preparations for its first commercial plant abroad.
Using wastewater to grow a carbon sink
Arrhenius cultivates microalgae in outdoor photobioreactors. The algae use sunlight for photosynthesis and nutrients from wastewater to grow, binding atmospheric carbon dioxide into biomass while cleaning the water. The company then harvests and dries that biomass before placing it in long-term underground storage.
The operating logic connects two processes that are usually treated separately. Wastewater supplies nutrients that would otherwise need to be manufactured or sourced, while algae growth turns those nutrients and sunlight into carbon-rich material. Arrhenius says the dried biomass contains more than 50% carbon and that storage conditions can keep it stable for more than 1,000 years.
That creates a potential carbon-removal product, but only if the company can measure the biomass, verify its carbon content and demonstrate durable storage. Arrhenius plans to issue carbon-removal certificates based on the measured CO₂ removed. As EUVC's carbon-removal analysis argues, measurement, reporting and verification are part of the product rather than administrative work around it.
The pilot plant is the commercial test
The seed round moves Arrhenius from smaller systems toward a 500 m² pilot plant under real operating conditions. The company says the facility will combine carbon removal with wastewater treatment and establish the basis for a first commercial plant abroad.
The pilot has to prove more than algae growth. Arrhenius must show that its photobioreactors can operate reliably outdoors, that wastewater inputs remain manageable, and that harvesting, drying and storage preserve a credible carbon balance. It also needs repeatable monitoring that buyers and standards bodies can audit.
If those pieces work together, the model can earn revenue from verified carbon-removal certificates while offering wastewater operators a treatment benefit. The commercial advantage would come from integrating capture, water treatment and storage into one system. The next meaningful milestones are therefore operating data from the pilot, cost per tonne removed and evidence that the process can be replicated at a commercial site.
Sources checked:
Arrhenius funding announcement · Arrhenius technology · Arrhenius contact · Lucerne Business · Carbon Herald · Tech.eu Funding Explorer
