Plastic waste has emerged as a global
environmental priority. It is the most prevalent type of marine debris found in the oceans and waterways.
Within the shipping
industry, the International Maritime Organization (IMO) has turned its attention on addressing marine plastic litter from ships. In 2018, the IMO's Maritime Environmental Protect Committee
adopted the IMO Action Plan to Address Marine Plastic Litter from Ships. This action plan aims to enhance existing regulations and introduce new supporting measures to reduce marine plastic litter from
ships.
One big source for
microplastic contamination into the ocean is the release of grey water. Grey water includes drainage from dishwashers, sinks and showers and can contain contaminants like oil, disinfectants,
fecal coliform and micro-plastics.
Current greywater treatment systems that are found on vessels do not filter for microplastics and unlike ship's blackwater, greywater is not regulated through the International Maritime
Organization under MARPOL Annex IV.
Furthermore, in the event that the ship's
wastewater systems combine black and grey waters for treatment, the treatment standards under MARPOL Annex IV do not account for the capture and extraction of microplastics and therefore
treatment systems installed on ships would not present this function.
There are several environmental impacts of
grey water dumping, including the potential for nutrients in the effluent to foster excessive algal growth, leading to dead zones for aquatic life.
Numerous studies have shown that marine life readily ingest microplastics and thus introducing them into the food chain as humans consume fish.
Finally, micro particles, if untouched, will degrade to nano-particles which could then start to affect DNA.
In summary the regulation of ships grey water is overdue and there is a great need for customized wastewater treatment systems that can capture and extract microplastics in quantifiable amounts prior to discharge.