Ballast water systems: what shipowners really want

Not all ballast water treatment systems are the same system design limitations can have a big impact on the efficiency of the system

One of the first lessons learnt by shipowners now operating ballast water treatment systems (BWMS) on newbuildings, or recently retrofitted systems on older ships, is that IMO /or US Coast Guard (USCG) type-approval is not guarantee of 100% performance. Why is that?

DHI business development and project manager Gitte Ingelise Petersen explained some of the misconceptions. DHI is a Danish-based firm which has a 50-year track record in developing and implementing solutions that meet real-life challenges in water environments worldwide. This includes being an approved independent laboratory (IL) for the testing of ballast water treatment systems (BWTS). DHI is accredited to ISO standards, for IMO and USCG standards and for class societies like DNV, ABS, as well as being involved in the development of BWMS for manufacturers, too.

“Over the last 10 years we have done testing for more than 25 ballast water (system) manufacturers and more than 50% of the current type-approval testing has been done or part done with us here in in Denmark,” said Ms Petersen.

Ms Petersen was speaking at the Riviera Maritime Media What shipowners want and need from the BWMS industry and its regulators in 2022 webinar, held in January 2022. The webinar was sponsored by Ecochlor, DHI and Headway. Ms Petersen explained that the core issue as to why a type-approved BWMS fails to meet expectations in real life is that prior to the introduction of the D-2 standard, there was no rule on system design limitations and monitoring testing.

Ms Petersen referred to paragraph USCG Ballast Water FAQs 18.3, which states: “What operational parameters must be considered for type approval testing? The Coast Guard has not identified a set of specific parameters applicable to particular types of treatment technologies that must be addressed in the testing. The manufacturer must identify any operational parameters or design limitations (e.g., minimum UV transmittance or intensity, water temperature, etc.) for the proper operation of the system. These manufacturer claims will be taken into consideration by the IL during test plan development.”

“Shipowners must look closely at the system design limitations listed on the certificates”

“When selecting an approved BWMS, shipowners can be certain that the system was tested to comply with the biological discharge standard D-2. However, prior to the IMO BWM code, the regulations had little or no reference to design limitations,” said Ms Petersen, “and a reliable description of the system design limitations is essential for choosing the right BWMS.”

Ms Petersen said that shipowners must look closely at the system design limitations listed on the certificates and be aware of the limitations inherent in testing. For instance, she noted that salinity and temperature are listed; UV systems are not impacted by salinity and temperature, but electrochlorination systems are. However, it is not possible to realistically organise testing at different water temperatures – it is dependent on the season and where the testing is taking place.

A more complex issue is the relationship between system design limitations, filter or no filter, TRO consumption and the quality of water in different ports and harbours. Ms Petersen had prepared a table based on the System Design Limitations (SDLs) listed in USCG type-approval certificates.