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Port of Singapore prohibits the discharge of washwater from open-loop scrubbers

6 December 2018

The Maritime and Port Authority (MPA) of Singapore announced a prohibition on the discharge of washwater used in ships open-loop SOx scrubbers. The prohibition is effective from January 1, 2020.

“The discharge of washwater from open-loop scrubbers is prohibited in Port of Singapore. This is to maintain Singapore Port’s marine water quality standard,” said the MPA in their IMO 2020 Fuel Oil Sulphur Limit guidance for ships. “While in the Port of Singapore, vessels fitted with hybrid type of scrubbers should switch to the closed-loop mode of operation. As for vessels fitted with open-loop scrubbers, they would need to switch over to compliant fuel instead.”

“It would be advisable to carry out the switch to either closed-loop mode or to compliant fuel well in advance of the vessel’s arrival at the port waters, so that any operational issues can be identified and dealt with before the ship starts maneuvering in heavy traffic.”

The Port of Singapore prohibition appears to be the first-ever ban on the discharge of washwater from SOx scrubbers. The decision by Singapore—the world’s biggest hub for ship bunkering—sends a signal to the shipping industry that a switch to a low sulfur fuel may be a less risky option to comply with the IMO 2020 marine fuel regulations.

Singapore authorities said the Port will provide reception facilities to receive the residues generated from the operation of hybrid/closed-loop scrubbers, as required by the IMO MARPOL Annex VI regulations. Supplies of neutralizing agents/chemicals used in closed-loop scrubbers (such as NaOH, Na2CO3 or MgO) will be permitted in the Port.

The IMO rules require that ships reduce the maximum sulfur content in their fuels to below 0.5% (compared to the current 3.5%), effective January 1, 2020. In lieu of switching to low sulfur fuels, ships are allowed to install exhaust gas treatment systems (EGTS) to control SOx emissions—commonly referred to as SOx scrubbers. Most ships that already installed scrubbers opted for the least expensive open-loop systems that use seawater to absorb SOx, and then discharge it into the sea.

Under the Singapore washwater discharge prohibition, ship operators who installed open-loop scrubbers to avoid the use of low sulfur fuels would still need to switch to a low sulfur fuel in the Port of Singapore. These ship operators will likely try to switch to competitive bunkering locations, with a potentially negative effect to the Singapore’s bunker market.

The Singapore decision was criticized by the Exhaust Gas Cleaning Systems Association (EGCSA)—an industry group for marine exhaust gas cleaning system technologies.

The discharge of scrubber effluents into the sea carries a number of potential risks to the ecosystem. These include the reduction of the pH value, the increase in the chemical oxygen demand (COD) due to oxidation of sulfites carried by the effluent, temporary temperature rise, increased turbidity, and discharge of other pollutants such as heavy metals. The discharge of sulfates is considered a lesser risk factor, because sulfates are stable chemicals that are naturally present is sea waters. If scrubbers are used, closed-loop systems or dry scrubbers are preferable to open-loop systems, concluded a 2015 analysis by the German UBA.

Source: MPA Singapore