<![CDATA[NOx emissions from marine diesel engines constitute a significant source of air pollution, contributing to tropospheric ozone formation, acid rain, respiratory health hazards, and greenhouse gas accumulation. Under MARPOL Annex VI regulations, vessels operating within designated Emission Control Areas (ECAs) must comply with Tier III NOx emission limits, necessitating the installation of exhaust gas treatment technologies. This study examines the application of Exhaust Gas Recirculation (EGR) technology on the MAN B&W 6S60ME-C10.5-EGRBP two-stroke main engine on board MV. Maersk Noresund, a 25,805 GT container vessel built in 2021 and operated by Sealand Maersk Asia. The research was conducted during the author's sea practice period from June 23, 2021, to July 12, 2022, using a descriptive qualitative approach with data collected through direct observation, interviews with engineering officers, and documentation review. The study analyzes two primary aspects: the environmental problems caused by NOx emissions from the combustion process, and the operational role of the EGR system in achieving Tier III compliance. The EGR system operates by recirculating approximately 30% of treated exhaust gas back into the scavenging air receiver, replacing a portion of oxygen with CO₂, which has a higher heat capacity. This reduces the peak combustion temperature and consequently minimizes thermal NOx formation. The exhaust gas undergoes pre-spray scrubbing with NaOH solution to neutralize sulfuric acid and remove particulates, cooling in the EGR cooler, water mist separation, and pressurization by the EGR blower before mixing with scavenging air. A comparative evaluation of EGR versus Selective Catalytic Reduction (SCR) and Planned Maintenance System (PMS) versus General Overhaul strategies demonstrates that EGR offers advantages in implementation cost, fuel efficiency improvement, and compatibility with existing engine designs, while PMS provides superior preventive maintenance benefits over periodic overhaul approaches for sustaining optimal EGR performance.]]>
