By Coldep
First scientific demonstration of norovirus extraction from seawater by vacuum flotation.
As part of the NoVLess project, conducted with a consortium of six scientific and institutional partners, French water treatment company Coldep has demonstrated that its VAL AQUA technology reduces norovirus levels in seawater by 95% in just 120 minutes. The experiments, carried out at the Mediterranean Marine Environment Station (SMEL) in Sète, France, between 2025 and 2026, following a protocol reviewed by IFREMER, represent the first scientific proof that a vacuum flotation process can extract norovirus from seawater. For a shellfish industry that has had no proven technical solution against this viral threat, these results open a concrete path forward.
Coldep announces the results of the NoVLess project, carried out with a consortium of six scientific and institutional partners: its VAL AQUA technology achieved a 95% reduction in norovirus levels in seawater within 120 minutes.
The experiments were conducted between 2025 and 2026 at the Mediterranean Marine Environment Station (SMEL) in Sète, France, following a protocol reviewed by IFREMER, France’s national reference institute for marine science. They constitute the first scientific demonstration that a vacuum flotation process can extract norovirus from seawater.
For the global shellfish industry, these results mark a turning point. Until now, no technical solution had proven effective against norovirus, which causes recurring contamination events, prolonged harvesting area closures and significant economic losses for producers worldwide.
Robust, Reproducible Results Across Two Seasons
- 95% viral load reduction in treated water within 120 minutes (from 37 to 8 million genomic copies per liter).
- x21 concentration factor in the collector (from 12M to 254M GU/L, +1.3 log) — confirming the physical microbubble extraction mechanism.
- Mass balance verified: The viral reduction in treated water correlates directly with accumulation in the collector. The mechanism is physical and confirmed.
- Two seasons tested: Summer conditions (April–May 2025) and winter conditions (January 2026, with viral loads 15 times higher) for robust assessment.
- Independent dual analysis: Every sample analyzed by two independent laboratories — IAGE (digital RT-PCR) and LDV34/Hérault Departmental Veterinary Laboratory (quantitative RT-PCR). Cross-validated, concordant results.
- Protocol reviewed by IFREMER, France’s national reference institute for marine science.
Regarding oysters: VAL AQUA acts on the water, not on the shellfish’s metabolism. By removing viruses from the tank water, it eliminates the source of recontamination and thereby supports natural depuration.
“Norovirus particles are just 30 nanometres in size. Until now, no one had demonstrated that a flotation process could extract particles that fine from seawater. That is what the NoVLess project establishes. And we did it under real conditions, across two seasons, with winter viral loads fifteen times higher than summer. The results hold”,— Bertrand Barrut, CTO, Coldep.
A Global Challenge for the Shellfish Industry
Norovirus is the leading cause of acute gastroenteritis worldwide and is responsible for over 40% of foodborne illness outbreaks linked to shellfish consumption. Because oysters are filter feeders, they naturally concentrate viral particles present in their environment.
This is not a localised problem. From Ireland to Australia, from Chile to Spain, shellfish-producing regions face the same pattern: winter contamination events, prolonged harvesting closures, economic damage to producers, and growing regulatory pressure — with no validated technical solution available until now.
Two Concrete Deployment Pathways
Upstream — VAL AQUA installed at wastewater treatment plant outlets to eliminate viruses before discharge into coastal waters and shellfish farming zones.
Downstream — continuous water treatment in holding and depuration tanks to prevent recontamination and support natural depuration.
A Proven Technology, Now Backed by Nijhuis Saur Industries
The VAL process (vacuum airlift flotation), at the core of VAL AQUA, is patented and Solar Impulse-labelled since 2021. Its first deployment in shellfish farming dates back to 2018. Today, over 100 aquaculture sites worldwide are equipped — including fish farms (RAS), shellfish operations and public aquariums.
Since October 2025, Coldep is part of Nijhuis Saur Industries (NSI), a global leader in water treatment. This integration strengthens Coldep’s deployment capacity while preserving the agility of its Montpellier-based engineering team.
About Coldep
Coldep is a French company specialising in high-performance water treatment. Its patented VAL (Vertical Air Lift) technology originated from research conducted at IFREMER and INSA Lyon. Initially developed for aquaculture, it now extends to other high-potential applications including desalination pre-treatment and PFAS removal. Coldep has equipped over 100 sites worldwide and has been part of Nijhuis Saur Industries since October 2025. coldep.com
