Gray Water Spill Highlights Need for MARPOL Update

Reports that a cruise vessel discharged several thousand liters of food waste and gray water into the Great Barrier Reef should send a clear message to the IMO that MARPOL Annex IV needs urgent revision, said Mark Beavis, Managing Director of ACO Marine.

While the alleged incident of August 26, 2018 is still under investigation by the Australian Maritime Safety Authority, the pulped slurry could have been transferred from a food waste holding tank to the ship’s gray water holding tank from where it was unintentionally discharged overboard into the protected marine park. 

“There are local rules regulating the discharge of ships’ gray water, but there is still no internationally-enforced requirement to prevent the damage that this waste stream can have on the marine environment and, ultimately, human health. Grey water is a such an under-reported threat; much more so than oily water, black water and sewage,” said Beavis.

When discharged into the marine environment, the oils, fats, detergents, chemicals, greases, galley waste and micro- and nanoplastics that make up the gray water stream can flood the surrounding environment with nutrients. “It overloads the biological make-up of the ecosystem, is being consumed by marine life and is entering the food chain,” said Beavis.

In October, researchers at the Medical University of Vienna and the Environment Agency Austria published the results of a small study into the amount of microplastic found in human stools. The study, the first of its kind, analyzed stool samples from eight participants around the world. None of the participants identified themselves as vegetarian and six ate fish. The samples contained up to nine different plastics of between 50 and 500 micrometers in size. On average, researchers found 20 microplastic particles per 10g of stool.

“Up to five percent of all the world’s plastic ends up in the ocean, finding its way into seafood, including tuna, lobster and shrimp,” said Beavis. “A significant amount of this microplastic is being discharged in the gray water generated by the global shipping fleet but, as an industry, we can reduce this by simply revising existing legislation.

“If we follow the spirit of MARPOL Annex IV, then gray water must be added, because it has a far greater environmental and human impact than any other wastewater stream.”