Bangladesh’s river network of almost 230 rivers, serves as crucial transportation routes for millions of passengers annually. Despite ratifying international conventions on marine pollution, Bangladesh lacks a National Marine-Environmental Protection Policy. Therefore, dumping untreated waste into water bodies has become habitual due to the absence of monitoring of effluent-releasing standards. This research aligns with the urgent need for a sustainable waste management model in the maritime sector, considering the inadequate waste management practices and the country’s vulnerability to climate change. The proposed model integrates a biogas-composting plant within a passenger ship and a plastic segregation chamber. This innovative solution addresses organic waste from ships, generating biogas for cooking, a sustainable alternative to LPG. The plastic segregation chamber facilitates the proper storage and sale of plastic waste for recycling, fostering a circular economy and reducing the demand for new plastic production. Aligned with multiple Sustainable Development Goals (SDGs), the research promotes environmental protection, energy independence through biogas, and a more resilient infrastructure. It aims to reduce greenhouse gas (GHG) emissions and improve air and water quality by solving the longstanding waste management challenges in the maritime sector of Bangladesh.