I would like to bring the following aspects into the discussion on deoxygenating ballast water.1 There is a vast difference between real circumstances in ballast tanks and a laboratory circumstance—much bigger difference than usual between the laboratory and the field. To make any even indicative conclusions, some trials should be carried out in a small-scale real situation.
The biggest difference is that in an untreated or poorly treated ballast tank you have already various degrees of rusting in thickness up to about 10 mm, sometimes even more. This rust deposition contains enough oxygen to allow some of the spores to survive even though the water was deoxidized by nitrogen. Nitrogen has to be applied for a very long time to deplete—if at all—the "structural" oxygen of the rust deposits.
Secondly it may prove very expensive indeed to install a nitrogen distribution system that effectively would remove the oxygen from...
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