You can go filterless – with chlorine dioxide treatment technology

Mar 08 2022

You can go filterless if your ballast water management system uses chlorine dioxide technology, because its effectiveness is not reduced by any sediment, says Andrew Marshall, CEO of ballast water management system manufacturer Ecochlor.

There are certain advantages to utilizing a filter within the treatment process of a ballast water management system (BWMS).


Some shipowners view it as an additional level of security in ensuring BWMS efficacy.


Whilst this is certainly a strong argument for adding a filter, the reality is that under certain water conditions a filter can also bring real problems to the ballast operation.


For example, in turbid or “dirty” waters, clogging can become problematic with some filters due to their mesh design or screen size in relation to the rate and quality of the dirt load presented to it. 


Extended back flush cycles can reduce the ballast rate, whereas the need for additional piping and equipment results in an increased maintenance overhead for the BWMS.


So why filter?  The simple answer is because most BWMS treatment technologies don’t work very effectively without one.


An ultra violet (UV) BWMS must use a filter because it requires the removal of sediment to enable the UV light to hit all the organisms, rather than them be shielded by silts or sediments. There is no option for UV BWMS treatment without a filter.


Likewise, as a reputable electro-chlorination (EC) manufacturer has confirmed, the EC treatment technology doesn’t lend itself well to a filterless system due to the need to significantly increase the chemical dose in order to be certain to treat ballast water effectively.


This not only raises the power requirements (and by extension, the carbon footprint of the vessel) but can also cause damage to the ballast water tank coatings.


Chlorine dioxide

Early last year Ecochlor launched the EcoOne filterless BWMS, which is well-suited for use as a no-filter system.


Why? Because, the chlorine dioxide (ClO2) treatment technology is particularly effective in all water conditions, especially turbid water as a direct result of the chemistry that is at the heart of the system.


“Filtration to remove sediments prior to treatment with ClO2 is simply not necessary,” stated Pete Thompson, Vice President of Operations.


“In contrast, Sodium hypochlorite or EC-based technologies react with any organic matter living or dead.”


“This means in waters with high levels of total suspended solids, the sodium hypochlorite reacts with everything, so there is a need to significantly increase the dose, lest the operator run the risk that there will be insufficient hypochlorite left over to kill the organisms.


 “On the other hand, ClO2 treatment reacts primarily with living organisms, rather than all organic matter.


“Due to this limited reaction with non-living organisms, the need to increase the dose to effectively treat the ballast water is minimal. As a result, power consumption remains extremely low and vulnerable tank coatings are still protected.”


The benefits to the crew in operating a BWMS without a filter are vast since issues with some filters can be severe, especially in heavy challenging waters.


With fewer operational obstacles along with less maintenance requirements, these new Ecochlor filterless BWMSs are an attractive option for shipowners.


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