Assessment of Efficiency and Environmental Impacts of Biomass-Fueled Conventional and Centralized Mushroom Substrate Sterilization Systems

Simple and low-cost sterilization equipment is frequently used to disinfect the substrate in cottage-level mushroom production. This study evaluates the performance and environmental impacts of conventional and centralized mushroom substrate steam sterilization systems using biomass fuels. Two systems, namely, conventional steam sterilization equipment (ConSSE) and centralized steam sterilization equipment (CenSSE) were experimentally tested with wood fuel and rice husk under controlled conditions. Key performance parameters, including temperature, pressure, fuel consumption, water usage, and processing time, were measured, while environmental impacts were assessed using life cycle assessment (LCA) with selected midpoint indicators. The results showed that neither system achieved the recommended sterilization conditions of 120°C and 151 kPa, indicating limitations in current designs. However, the CenSSE with four sterilization units demonstrated superior performance, reducing total processing time by 68.5% compared to ConSSE. Rice husk combustion resulted in higher burner efficiency (18.8%-23.1%) than wood fuel (10.8%-11.2%), leading to lower biomass consumption and reduced environmental impacts. Among all combinations, ConSSE with wood fuel exhibited the highest global warming potential, while CenSSE with rice husk showed the lowest environmental impact. The findings highlight that the integration of improved burner design, appropriate material selection, and the use of rice husk as a renewable fuel can significantly enhance system efficiency and sustainability. The automation of CenSSE achieved the sterilization conditions of 118.5°C and 144 kPa. Further, automated control of blower speed and rice husk feeding rate reduced the time required to reach the target temperature by 38.7%, decreased the total sterilization time by 21.2%, reduced the rice husk consumption by 12.3% and improved the burner efficiency by 23,3%. Thus, integration of automation and real-time control using IoT has potential to enhance energy efficiency, and operational reliability.