Hybrid multiple-criteria decision-making for bulk carriers ballast water management system selection

Ballast water is essential in maritime transport to maintain the stability of navigation. However, alien invasive species brought by ballast water may jeopardize the integrity of the aquatic environment, including marine, brackish and freshwater. Therefore, the International Maritime Organization (IMO) established stricter ballast water discharge standards after 8 September 2024. Under the new regulations, selecting an appropriate ballast water management system (BWMS) might pose a challenge for shippers. In this study, we worked with several domain experts and applied the fuzzy analytical hierarchy process (FAHP) to set up two decision support frameworks for bulk carriers larger or smaller than 40,000 gross tons. Results indicate the assessment criteria and their associated weights. The "Ballast Water Management System Manufacturer" criteria was the priority consideration for large vessels, whereas the "Space" criteria was the priority consideration for small vessels. We also applied TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) to sort the advantages and disadvantages between different systems. The results show that regardless of how large or small the vessels are, the ozone treatment system is favored by shippers due to the higher confidence placed in this industry. Validating these methods can provide valuable decision-making support for shippers to select a suitable BWMS.