Abstract
This study proposes an integrated system consisting of steam sterilization, a vapor-injection heat pump, and a drying unit for the treatment of infectious medical waste (IMW) and the production of refuse-derived fuel type 3 (RDF-3). The system combines waste sterilization, moisture removal, air quality improvement, and energy recovery to improve both environmental and economic performance. Thermal simulation, prototype development, and experimental validation were conducted to evaluate system performance. The results indicate that the system can process IMW at a rate of 240 kg/d, producing 85.62 kg/d of RDF-3 with a significant reduction in moisture content from approximately 85% to below 10%. A drying process with a heating requirement of 20 kW is effectively supplied by a high-temperature vapor-injection heat pump with a condenser capacity of 20.76 kW at a hot water temperature of 90 °C. The system achieves a heating coefficient of performance (COP) of 2.39 kWth/kWe, demonstrating efficient energy utilization. Environmental analysis shows that the proposed system can reduce greenhouse gas emissions by 297.49 t CO₂-eq/y (68.11%) compared to the conventional landfill-based scenario. Furthermore, the implementation of a vapor-injection heat pump for condensing moisture from the exhaust air of the steam sterilization process contributes to improved air quality, ensuring compliance with international standards, particularly for total volatile organic compounds (TVOCs) at 0.3 ppm and volatile organic compounds (VOCs), specifically acrolein, at 0.18 μg/m3. From an economic perspective, the system requires a total investment of 27,560 USD and generates a net annual income of 3570 USD. The levelized cost of IMW treatment is reduced to 0.0418 USD/kg, significantly lower than that of the conventional system (0.6445 USD/kg). The payback period and internal rate of return are 7.72 years and 11.48%, respectively. Overall, the proposed system demonstrates strong potential for sustainable IMW management by integrating sterilization, drying, air quality improvement, and energy recovery into a single process, offering significant energy savings, emission reductions, and economic benefits.