A three-year study has found that scrubber washwater is “effective and safe for the ocean environment”, according to Ian Adams, executive director, Clean Shipping Alliance (CSA) 2020.
The study, which was led by Carnival, compared 281 washwater samples from 53 scrubber-equipped cruise ships to generate the largest washwater data set in the marine industry. The samples were assessed against 54 different test parameters by ISO accredited independent laboratories. The scrubber results compared favourably with all of these standards.
DNV GL evaluated and compared the results against various water quality standards following confirmation that the samples analysed were consistently well within the allowable IMO criteria and regulatory limits.
The results were also compared with selected national and international water quality standards and land-based washwater discharge limits to serve as study benchmark standards. The scrubber washwater compared favourably with the standards.
Mike Kaczmarek, Carnival’s senior vice president, 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 recognised 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).”
Mr Adams, added: “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.”