A proposal from industry to weaken the pH standard for ship exhaust-gas scrubber wash-water discharges to the sea from pH 6.5 to pH 3.0 has failed to win the support of a key IMO committee.

A proposal from industry to weaken the pH standard for ship exhaust-gas scrubber wash-water discharges to the sea from pH 6.5 to pH 3.0 has failed to win the support of a key IMO committee.

The proposal from Interferry was supported by a Danish study suggesting that the move would not pose a threat to the environment, but the 17th session of the IMO’s Bulk Liquids & Goods Sub-Committee (BLG17) decided that not enough was known either about the need for such a reduction in the pH standard nor the likely environmental impact for a decision to be made.

Scrubbers, which remove sulphur from ship exhaust gases, are being developed and marketed as an alternative compliance mechanism for the requirement to burn low sulphur fuel in ships, but the regulations require that such mechanisms do not cause harm to the environment. While it is unclear what impact the likely quantities of wash-water are going to have on the marine environment, increasing ocean acidification as a result of rising levels of atmospheric CO2 is a serious and well documented problem.

The IMO will revisit the issue at BLG18 in 2014.