IMO's updated guidance on anti-fouling coating removal

The International Maritime Organization issued revised guidelines for the safe removal of anti-fouling coatings from ships, emphasizing the environmental risks associated with biocide release.

Following the approval of the 2023 Guidelines for the control and management of ships' biofouling to minimize the transfer of invasive aquatic species (2023 Biofouling Guidelines, resolution MEPC.378(80)), the Secretariat identified a number of subsequential and editorial revisions. The revised version of the 2023 Guidance on best management practices for removal of anti-fouling coatings from ships is therefore set out in the annex to the circular (you can see it in the document below).

Anti-fouling systems on ships prevent issues like increased drag, fuel consumption, and emissions caused by fouling. These systems, whether containing pesticides or not, historically used biocides, some of which posed threats to aquatic life and faced international restrictions or bans. Self-polishing polymer coatings are the most effective, gradually releasing biocides as ships move through water, though this can harm unintended organisms. Removing these coatings also releases biocides, highlighting the need for careful system selection and management to minimize environmental impact.

Methods for coating removal include scraping and blasting. Scraping involves manual or mechanical removal, while blasting uses abrasive materials like grit, typically in enclosed areas or dry docks to prevent biocide dispersion.

The document stresses good housekeeping and clear management in facilities handling coatings, emphasizing record-keeping, equipment security, and worker training. Designated staff manage waste and wastewater, ensuring proper handling of cleanings, paint chips, dissolved biocides, and contaminated grit, all stored separately and promptly removed for treatment at specialized facilities. Waste must not be washed into the environment, buried, incinerated, or stored onsite.

Wastewater containing hull coating waste is collected in closed tanks or containers, with suspended particles settling before treating the water to meet standards and avoid marine sensitive areas. Treatment methods address dissolved anti-fouling components, with contaminated sediment managed at licensed facilities.

Recommendations for grit blasting waste include reuse after cleaning or transport for safe disposal. Wastewater from wet blasting is contained, and remaining grit collected for reuse, recycling, or disposal.