The COLDEP process resolves the main technical limitations encountered by shellfish purification systems in shellfish farming facilities:

  • Presence of bacteria and viruses in the water.
  • Abundance of small particles <30 µm which are not captured by conventional filters and reduce the effectiveness of UV treatments.
  • Decrease in dissolved oxygen concentration in water.
  • CO accumulation2 dissolved in water.
  • Energy cost of the solutions implemented to solve these problems.
particulate extraction - Compatibility - biosecurity

Shellfish water purification

The microbubbles created in the system trap impurities as they rise and create a scum at the top of the column. This scum which is sucked up by the vacuum carries with it the particles which are trapped inside. These extracted particles are between 0.3 and 30 µm and are not trapped in conventional systems.

Minimum size of the particles extracted


Transmittance indicating water clarification


Reduction of bacterial load

Maximum quantity of shellfish treated by a VAL1400 in 200 m³ of water

Maximum electricity consumption per m³ of treated water

Less viral load

Particle extraction by the COLDEP system also makes it possible to trap bacteria and viruses, thus ensuring the biosecurity of breeding waters. Water clarification also helps to ensure optimal UV efficiency, coupled with the extraction function which eliminates degraded particles that UV and ozone treatments neutralize but leave in the environment. There is the possibility of extracting continuously or only a few hours a day.

Dissolved gas management

Regulation of O concentration2 and co2

The bubbles associated with the vacuum created at the top of the column make it possible to achieve unmatched aeration and degassing efficiency.


Minimum oxygen saturation level


Reduction of the quantity of CO₂ in a single pass

CO2 graph
The opinion of professionals


Our new building comprises 230 m3 shellfish purification tanks, for a total volume to be treated of 430 m3 retrieved directly from the Thau lagoon. The initial plans included conventional pump technology, sand filters and UV treatments. Exchanging this set for the only COLDEP device allowed us eight times less electricity consumption, and superior water quality performance both in filtration and purification and in oxygenation.
Guy Sanchez

General manager, GUY SANCHEZ OYSTERS

we did it

Our references



Sanchez Guy, Port de Loupian Le Bourbou, 34140 Loupian

Application use: Oyster purification
Function (s): Particulate extraction
Model (s): VAL1400 + 2 VAL900
Installed in October 2019 through Coldep

Installation – Satmar


Copalestre 50310 Lestre, France

Application use: Oyster purification
Function (s): Circulation + Particulate extraction
Model (s): VAL1400
Installed in October 2021 through Coldep

Installation – Les Viviers de Keraliou


120 Route de Porz Keralliou, 29470 Plougastel-Daoulas

Application use: Purification of shellfish and crustaceans.
Function (s): Circulation + Particulate extraction
Model (s): VAL1400
Installed in June 2020 through Coldep