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Ballast Water Treatment Technology

Testing centre urges less pessimism over ballast treatment

Tue 27 Feb 2018 by Paul Gunton

Testing centre urges less pessimism over ballast treatment
This graph shows that, in some tests, BWMSs have reduced zooplankton concentrations by a factor of 1M (credit: Golden Bear Research Center)

Reports about the effectiveness of type-approved BWMSs and the rigorousness of their testing have a “pessimistic tone”, said staff at the Golden Bear Research Center in the US in a statement issued yesterday. Nonetheless, there are “shortcomings [in] existing regulations,” the facility’s chief engineer Bill Davidson told BWTT today (27 February).

He was summarising a lengthy response to what he and his colleagues view as a negative reaction in reports of the closure of two testing centres, MERC in the US and DHI in Singapore. It has been distributed through GloBal TestNet – whose members are other testing centres – and via the media and said that “a one-million-fold reduction in anthropogenic ballast water organism transport is cause for celebration, not criticism.”

Yet Mr Davidson and his colleagues agree with remarks made in December by MERC director Dr Mario Tamburri who said that ‘non motility’ in suitably large stationary eggs of some invertebrates would mean they were be considered to be ‘non-living’ organisms and thus meet USCG ballast regulations, even though they may hatch at a later time.

The statement also mentions “another potential unsettling circumstance considering the interpretation of organism size” relating to a single-celled organism that is responsible for “routine shellfishery closures and marine-life kills along the west coast of North America.” Its minimum dimension of 5 µm is less than the USCG’s 10 µm limit so would not be counted.

However, to cite these examples as pointing to “patent failure of ballast water treatment systems in the abatement of the aquatic invasive species problem,” is wrong, the statement’s authors believe. “We take objection to such a position,” they said, urging “a global and realistic evaluation of ballast water treatment efficacy.”

Golden Bear researchers made more than 100 comparisons of the concentrations of ‘living’ organisms pumped into the test facility during both land-based and shipboard tests and the final discharge concentration of living organisms after ballast treatment. They found that the number of organisms had reduced by a factor of up to 1M, with half of the samples showing a reduction factor of between 100,000 and 1M (see graph, at the top of this news item).

“This level of organism reduction demonstrates that ballast water treatment effectiveness is fantastically high, approaching and even exceeding the stringency required in drinking water testing [and] food management practices,” their statement said. Applying those reductions to a global fleet of 60,000 ships would be as if the world fleet had been reduced to just 0.06-0.6 ships. “Would we suspect shipping to be a major global vector in the anthropogenic spread of aquatic invasive species at that level?” the statement asked.

Despite this, they said that it is “clear to us that the international and federal ballast water discharge standards need attention [or] correction to modify literal interpretations of the law that seem counterintuitive to ballast water management.”

BWTT asked whether the group thought it would be possible – both technically and from a regulation point of view – to deal with the deficiencies suggested in their statement and Mr Davidson said that this is “certainly a point of discussion for all stakeholders.” One of the other signatories, Prof Nick Welschmeyer, of Moss Landing Marine Laboratories, said “Our team will be meeting later this week and we will discuss your further questions.”

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