THE VOS™ BALLAST WATER TREATMENT SOLUTION

N.E.I. Treatment Systems has developed and commercialized the Venturi Oxygen Stripping™ (VOS™) System, a Type Approved Ballast Water Treatment System (BWTS) that is safe, cost-effective and reliable. The VOS™ System solves the invasive aquatic organism problem while protecting the ship’s ballast tanks against corrosion.

VOS™ Ballast Water Treatment Deprives Aquatic Organisms of the Oxygen Needed to Survive.

VOS™ induces a low-oxygen (hypoxic) condition in ship ballast tanks using inert gas. This hypoxic condition deprives aquatic organisms – both plants and animals – of the oxygen needed to survive. This low-oxygen environment also limits the amount of oxygen available to form iron oxide, or rust, thereby protecting the internal steel surfaces of the ballast tank against corrosion and preventing premature deterioration of ballast tank coatings.

In less than 10 seconds, N.E.I.’s patented VOS™ System safely removes 95% of dissolved oxygen from ballast water by mixing very low-oxygen inert gas with natural water as it is drawn into the ship as ballast. In a process similar to evaporation, the inert gas strips the water of its dissolved oxygen:


  • 1. The VOS™ Stripping Gas Generator (SGG) is turned on and provides low-oxygen inert gas to the Venturi Injectors.

  • 2. Once the ballast pumps are turned on, ballast water passes through the Venturi Injectors, where it is mixed with the inert gas from the SGG.

  • 3. A cavitation process with the inert gas creates a micro-fine bubble emulsion in the water.

  • 4. The dissolved oxygen diffuses from a liquid phase to a gas phase.


Upon discharge below the water line, the ballast water once again passes through the VOS™ Venturi Injectors, where air is re-introduced back into the water before release into the environment. As water exits the ballast tanks, the tanks are filled with inert gas in order to maintain a low-oxygen condition, which has two key benefits:

✓   When deoxygenated water is once again drawn into the ballast tanks, it will not re-oxygenate.
✓   Ballast tank coating life is extended and steel corrosion is reduced by up to 84 percent.

VOS Ballast Water Treatment Process Diagram