Ballast water discharged from ships is known to be one of the primary routes for the transfer of invasive species. With the imminent ratification of the IMO Ballast Water Management Convention shipowners are being forced to invest in ballast water treatment systems (BWTS), so protection from this threat to the marine environment is finally at hand … or is it?
Before we celebrate the end to the transfer of invasive species we need to recognise that some BWTS are unable to reliably treat ballast water so that they meet either the IMO or USCG discharge standards under the full range of real operating conditions.
As Lars Robert Pedersen, BIMCO’s deputy secretary general, said during IMO MEPC 69, “The shipping industry needs reliable ballast water treatment systems that are fit for global use. Presently, IMO-approved systems may not always live up to the required standards under real operating conditions on board ships.”
Most ballast water systems are installed to ‘do the job’ during ballasting after which, in some cases, it could be several days or even weeks before the ships need to de-ballast. It is that delay between treatment and discharge that sits at the heart of the problem now unfolding, because in that period the regrowth of organisms that will certainly have occurred could result in the vessel failing the Port State Control test.
Put simply, the regrowth of live organisms in the ballast tanks would mean that the numbers contained in the discharge water may well be above the standards set by the authorities, even though at a point in time immediately after the initial uptake treatment the water complied with the regulations.
So why is this only just coming to light? After all, regrowth is a natural phenomenon. The answer may lie in the fact that only some BWTS technologies can deal with the regrowth problem.
Resistance to acknowledge the potential for regrowth undermines the credibility of the BWT sector but more importantly threatens the goal of marine environmental protection that both the IMO and USCG regulations are intended to secure.
In addition, there are obvious and considerable financial implications for shipowners that select the wrong type of BWTS once the PSC grace period ends after ratification. Those with the largest ballast volumes and the longest ballast legs have most to lose.
Owners must remember that the IMO convention and its US equivalent are ballast water discharge standards, not water treatment standards. That means that the selection of BWTS should be made against the vessel operating requirements/criteria versus system limitations.
Andrew Marshall is the chief executive of Coldharbour Marine.