The first way of dealing with the ballast water problem was changing the ballast water at open sea. This method was used based on the assumption that coastal-dwelling organisms cannot survive in the open seas because of the differences in salinity, pH and temperature between different locations. However, the efficiency of this particular method has later been disputed as it may actually supply surviving organisms with fresh oxygen and nutrients and therefore be counter-productive.
Moreover, changing ballast water at sea also entails certain safety risks as the ship’s strength and stability are affected by water flowing in and out.
The challenges associated with changing ballast water at sea have initiated a search for other solutions, including various forms of water treatment. Research is being conducted in a number of locations worldwide into mechanical methods (filtration and separation), physical methods (ozone, UV, electricity, and heat treatment), chemical methods (biocides) and various combinations of the above.
PureBallast -A chemical-free water purification
In the early 2000's, Wallenius started to consider the ballast water problem. However, instead of waiting for a solution to be developed elsewhere we engaged in a water treatment company which had developed a technology called Advanced Oxidation Technology (AOT). The method of creating hydroxyl radicals proved to be extremely effective in breaking down the cell membrane of micro-organisms and bacteria. AOT generates no by-products or toxic residues once the process is complete - just sterile water is.
To industrialise this technology the company, later named Wallenius Water, started a frutiful cooperation with Alfa Laval. Together they developed a ballast water treatment system called PureBallast and it was commercially launched in December 2006.
During the ballasting process the water passes through a filter to remove sediment and particles and then continues to the AOT unit to be sterilized. Any filter residue and back flushing water can be returned to the ocean at the ballasting spot. During deballasting the water is treated again to remove organisms that might survived in the tanks. The filter is bypassed in the second process.
The unit is cleaned to keep the glass tubing free from coatings that could reduce the unit’s efficiency. A biodegradable fluid is used and recirculated until it is consumed.
No ballast - the optimal solution
There are no doubt that the best solution to the ballast water challenge would be a vessel without any need for ballast water. This however is a great challenge to the Naval Architects designing the coming generations of vessels.
Read about our results and statistics within ballast water