Study shows scrubber use meets environmental standards

A study carried out on washwater from scrubbers on cruise ships shows that it compares well with numerous water quality standards.

The results of the study were revealed by the Clean Shipping Alliance 2020 to coincide with the IMO’s PPR 6 meeting taking place in London this week.

The three-year, Carnival-led study collected 281 wash water samples from 53 EGCS-equipped cruise ships, the largest washwater data set in the marine industry, which were then assessed against 54 different test parameters by ISO accredited independent laboratories.

All the resulting laboratory analysis reports were then evaluated by Classification Society DNV GL’s Maritime Advisory Services and the data compared against various water quality standards, after first confirming that the samples analysed were consistently well within the allowable IMO criteria and regulatory limits.

Then the results were compared to selected national and International water quality standards and land-based wastewater discharge limits, including the German Waste Water Ordinance, the EU Industrial Emissions Directive 2010/75/EU, and the EU Surface Water Standards Directive 2013/39/EU. While these comparisons are not directly applicable to exhaust gas cleaning systems (EGCS), as well-established and representative water quality standards that are protective of the environment, they were appropriate to serve as study benchmark standards.

The EGCS results compared favourably with all of these standards.

Mike Kaczmarek, Carnival’s Senior Vice President for Marine Technology, said, “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).”

Ian Adams, Executive Director, CSA 2020, said: “We want to emphasise that this major study was intended to provide an objective assessment of the quality of scrubber wash water through a rigorous comparison to other world water quality standards, and it now represents the largest, most credible and verifiable data set available. And importantly, the results reaffirm that exhaust gas cleaning systems are effective and safe for the ocean environment.”

The report can be accessed at:

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