Japan’s MLIT and Carnival present scrubber findings at CSA 2020 conference

The Carnival-led and MLIT studies found that that the samples analysed were consistently well below the allowable IMO criteria and regulatory limits. The Carnival-led study then compared the wash-water parameter concentrations with EU and German emission limits for land-based industrial point source waste water standards, with which they complied.

Meanwhile, Shinichi Hanayama, Coordinator of Technical Staff at ClassNK’s Research Institute, who assisted in the MLIT presentation, concluded no “short or long-term effects on marine organisms can be caused by the use of open-loop scrubbers.”

“Japan has no intention to prohibit discharges from open-loop scrubbers around Japan or in Japanese ports,” Mr. Hanayama said in response to questions, adding the results of the MLIT study had been presented to the MEPC committee earlier this week.

Mike Kaczmarek, Carnival’s Senior Vice President for Marine Technology, “Comparing scrubber wash water to various other major water standards is useful to provide perspective and to illustrate EGCS wash water quality in a way that is easy to understand. These comparisons also provide relatable criteria for a number of specific EGCS parameters of interest, such as PAH concentrations, which also have limits within these standards.

“Although these are all recognized standards that are designed to regulate other waters, they do provide confirmation of the quality of water that operators of this technology are returning to the sea, and they provide strong support to the IMO’s decision to approve these systems as acceptable means of compliance throughout the world’s regional and 2020 global emission control areas (ECAs).”

The MLIT study of the potential impact of open-loop scrubbers on atmospheric emissions addressed the short- and long-term risks to the marine environment. It assessed the whole effluent toxicity (WET) upon algae, crustaceans and fish identifying PAH concentrations immediately after discharge from a model bulk carrier, adjusted for propeller cavitation. The study found that effluent concentrations would be diluted 500 times within three seconds and 5000 times within 60 seconds of discharge. As harmful levels of exposure for algae, fish and crustaceans range between 72 hours and 96 hours, the marine organisms could not be exposed to sufficient concentrations to cause short or long-term effects.

The MLIT study also included a long-term study to address the impact of long-term concentration of wash-water discharges on the water quality over a ten-year time period. In the absence of marine criteria, the MLIT study relied on Japanese land discharge criteria as a yardstick for comparison. The report noted “the heavy metals in the discharge water were lower than the emission standard for land-based discharges in Japan by an order of 100” [emphasis added].

The Carnival-led study, which began in 2016, initially gathered 79 wash water samples from 23 Carnival ships fitted with open-loop scrubbers. This data was supplemented by a second phase of the study in which an additional 281 wash water samples were taken from 53 ships. This data was then assessed against 54 different test parameters by ISO accredited independent laboratories, including metals, phosphorus and nitrates. Critically, the assessment included PAHs, which have emerged as a key area of concern in recent discussions about the environmental impact of wash water from open-loop scrubbers.

Classification Society DNV GL’s Maritime Advisory Services confirmed that the samples analysed were consistently well within the allowable IMO criteria and regulatory limits, before evaluating the laboratory analysis reports. The data was analysed by a net-post EGCS methodology, in which the values of the wash water assessed at the DeSOx outlet were compared against water quality values assessed at the SW inlet. In the absence of agreed international water quality standards for many of the parameters, the selected data was compared against indicative water quality standards from the EU surface water standards (part of EU Water Directive 2013/39/EU) and the German Wastewater Ordinance.

The study found that a few compounds and metals did occur in net post EGCS concentrations above 50% of the EU’s Surface Water Standard limit after applying three-sigma deviation and trimmed mean statistical methods. However, wash-water filtration appears to effectively reduce the parameters, including anthracene and dissolved nickel, according to a subsequent initial study of 11 samples taken from vessels fitted with wash-water filtration.