Phil Hughes Commercial Manager, Coldharbour Marine Ltd
Two steps forward… more confusion and a missed opportunity. The BWM saga continues
After ratification by Finland and then Panama in the last two months, the BWM Convention will enter into force on September 8th 2017. At MEPC 70, revisions to the G8 guidelines have been agreed which should help shipowners with the necessary system selection process by providing a yardstick by which different systems can be judged.
Scaling
Many systems have been tested for IMO Type Approval at or near their smallest operational size (less than 500m³/h flow rate for in‐line systems). However, successful scaling of a system cannot be relied on if the system has not been fully tested at or near the upper limit of its treatment rated capacity (TRC). A survey conducted by Class Society ABS of some 15 ship owners with a variety of systems fitted to their ships reported many issues when attempting to use these systems, with most success being attributed to those systems with lower TRC (i.e. less than 1000m³/h). For larger vessels where the TRC was 1000m³/h or higher, common issues such as filter problems, piping leakage, sensor failures, software problems, major component failures and insufficient electrical power available were common complaints.
In contrast, when Coldharbour conducted the ship‐based testing for the IMO Type Approval of its GLD™ in‐tank ballast water treatment system it specified that the tests should be carried out on board a VLCC. In doing so, Coldharbour customers can be absolutely confident that there are no issues of scaling even when the system is fitted to the largest of ships.
The Coldharbour Research, development and test centre
Total Suspended Solids (TSS)
GLD in ballast tank
More rigorous tests for how a BWMS copes with variations in the level of total suspended solids in ballast water is included in the revised G8 guidelines. Many owners already recognise that high TSS levels represent a major challenge for the filter systems which most in line treatment technologies use – especially if the vessel is relying on very high ballast pumping
rates during its terminal operations. The Coldharbour system does not use any filtration and during its type approval process was tested using high levels of naturally occurring TSS.
System Design Limitations (SDL)
Critical parameters known as System Design Limitations (SDL) are now not only to be identified by the manufacturer, but also validated during testing and indicated on Type Approval Certificate. Coldharbour has long held the view that no one system is suitable for all types of ship and all types of trading pattern. Establishing system limitations during testing for Type Approval will provide a prospective owner with a degree of objectivity when choosing a system.
That these revisions do no take effect until October 2020 should not deter prudent owners who are planning retrofits prior to that date from insisting that their chosen supplier can meet the demands of the revised guidelines. Indeed, failure to do so may result in the replacement of the BWTS after just one or two years of operation in order to comply with the revised G8 Guidelines. The good news is that owners can increasingly access higher quality information from reliable sources than is frequently found in the brochures of some BWTS vendors.
Regrowth – the missed opportunity
One area that owners must consider is the problem of organism regrowth in treated ballast water. While the System Design
34 Society of Maritime Industries Handbook & Members’ Directory 2017
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