- 12 December 2006 -

Ballast treatment system destroys harmful microorganisms

Alfa Laval has developed a filtration/oxidation system that can prevent the transport of potentially invasive species via ballast water.

Up till now, species transported via ballast water from one ecosystem to another have devastated marine life, collapsed local businesses and economies, and necessitated billions of dollars in control measures, the company says.

PureBallast is based on advanced oxidation technology (AOT), a chemical-free process similar to that used in many "smart products" including self-cleaning skyscraper windows. Depending on a ship's ballast water volume, PureBallast involves one or more AOT units, which treat the water during ballasting and deballasting operations. These units contain titanium dioxide catalysts, which generate radicals when hit by light. The radicals, whose lifetime is only a few milliseconds, break down the cell membrane of microorganisms - without the use of chemicals or the creation of harmful residuals.

During ballasting, water passes through a pre-filter to remove any larger particles and larger organisms such as some species of plankton. The water then continues to the AOT unit, which produces radicals that effectively break down smaller organisms that have passed the filter. Sediment buildup in the ballasting tanks is avoided due to the pre-filter stage, and any backflushing water is returned to the ocean directly at the ballasting site.

During deballasting, water again passes the AOT unit in order to destroy any organisms that might have regrown in the tanks during the voyage. The filter, on the other hand, is bypassed, thus avoiding any filter backflushing. This eliminates the risk of contamination via the filter at the deballasting site.

www.alfalaval.com