ATLAS-DANMARK Ballast Water treatment System (ABWS)

The Process

The biocide (the disinfection agent) applied in the system concept is often called “Electrochemical Activated Water” and contains a mixture of reactive molecules and meta-stable ions and free radicals.

This biocide mixture is called ANOLYTE in the following and will have an acidity of pH = 4 – 5, and is a very strong Biocide acting in the Ballast Water within few seconds. From the electrolytic cells used in ABTS also a reducing agent (called CATHOLYTE with pH = 10 – 11) will leave separately (about 10% of the ANOLYTE), containing reactive molecules and meta-stable ions. This CATHOLYTE will during the process be led to one or more of the Ballast Tanks, and would– after the ANOLYTE disinfection – in the ballast water tanks slightly increase the pH value and increase corrosion resistance, without any influence of the stability of the vessel.

The ozone and the other compounds in the ANOLYTE are injected during the Natural Flow after the Ballast Pumps and the Filters, and – when dissolved in the water – works in a synergy to create a very high so-called Redox Potential (in excess of 600 mV). When added to the filtered ballast water during the intake in a ratio of about 1:250 all microorganisms (and small organisms like eggs, larvae, etc.) will be killed within a few seconds. By using a pre-filtration Filter (self-cleaning) of less than 50 µ, the ANOLYTE ration will be reduced to 1:500 or less, depending of the Filter size. The Redox Potential can be likened to the electrical potential within thunderclouds relative to the ground, waiting to be discharged.

Therefore, the water in the ballast tanks will be practically “dead” throughout the voyage. During the voyage the Redox Potential in the individual ballast tanks will be measured. If the required Redox Potential drops to less than 100mV – 200 mV, the ballast water from the actual tank has to be injection with more ANOLYTE to raise the Redox Potential to the above-mentioned 600 mV. The process will continue until the redox potential is stabilized at about 200 mV. When discharging the ballast water in port, the ballast water is (still) free of living organisms and the data from these measurements will be used to verify the disinfection for the local Port Authorities for approval of discharge.

The process is based on the production of a very strong biocide (organism destructing agent), which is generated with very low power consumption and where the raw material is a solution of common salt (sodium chloride) in clean water. This biocide is absolutely nonpoisonous (actually it is drinkable – in small
quantities) and leaves no contamination traces when the disinfection is finished. The biocide is stable for up to several weeks and may therefore be produced during the voyage and stored aboard for use in connection with the next ballasting operation.

The requirement for the ballast water to be filtered is mainly derived from the IMO Convention requirements to remove particles above 50 µm, but will at the same time increase the “killing power” because of the ease for the biocide in penetrating the smaller particles. Subsequently, the Redox Potential will drop to about 200 to 300 mV – like in normal water – and all traces of the reactive compounds will disappear. At the same time the ANOLYTE will cause the organic remains from the organisms to dissolve over a short time – which will reduce formation of deposits in the ballast tanks substantially.