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Ballasting in Fresh Water

The Evoqua SeaCURE® System is the only  electrochlorination ballast water treatment solution which has both IMO and US Coast Guard AMS approval for operation in fresh, brackish and seawater.

All electrochlorination systems require the feed water to have a minimum salt content to generate sodium hypochlorite (biocide).  A distinct advantage side-stream systems have against full flow or in-line treatment systems, is the ability to use an alternative electrolyser feed supply to generate the required biocide. Average seawater has a salinity of 35 practical salinity units (PSU). When treating ballast water with salinities below 25 PSU, an alternative feed source with a higher salt content must be used to operate the SeaCURE system. The Aft Peak Tank (or similar) can be used for storing feed sea water. This allows SeaCURE system to continue to treat even when the main ballast water flow is fresh or low salinity brackish

SeaCURE system uses a treatment process that requires the equivalent of approximately only 1% of the ballast water flow to feed the electrolyser. In this way, the storage tank capacity does not need to be excessive large whilst still maintaining full ballasting capabilities (to treat 50,000m³ of ballast water the tank capacity would be 500m³).

 Normal and fresh water options to side-stream unit

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The SeaCURE system incorporates a water salinity (conductivity) analyser that advises the operator and system when the water being ballasted has insufficient salt content for economic chlorine production.


The less salt – electrolyte - that is contained in the water the lower the conductivity. This means more force is required  to drive the current through the water. The voltage needs to be increased, consequently the power consumption increases as well. At the same time the wear of electrolyzer coating increases with the voltage applied.

The salinity level chosen as electrolyzer feed in the SeaCURE system minimizes peak power and power consumption and increases the life time of the systems core component – the electrolyzer cell.

  • Use of a higher salinity feed in low salt environments reduces the power requirements.
  • Ballast Water Treatment is more efficient
  • Lower voltage requirement  reduces wear on electrolyzers.
  • Less system maintenance and longer lifespan
  • IMO tested and AMS accepted for all salinities, so system remains legislation compliant.
marine@evoqua.com Ballasting in Fresh Water