A Low-Cost Field-Deployable Mini-CEMS for Real-Time Diagnosis of Activated Carbon VOC Control Systems in Industrial Facilities

A low-cost and field-deployable monitoring approach for evaluating the performance of activated carbon (AC) adsorption systems in industrial volatile organic compound (VOC) control is proposed. A customized Miniature Continuous Emission Monitoring System (Mini-CEMS) was developed to simultaneously measure inlet and outlet VOC concentrations, temperature, humidity, and gas flow rate in real time. The system integrates a metal-oxide semiconductor (MOS) gas sensor, a dilution sampling unit, wireless data transmission, and a cloud-based database to enable continuous long-term operation in industrial environments. Field deployment was conducted at four manufacturing facilities with different VOC emission characteristics, including electronics production, semiconductor equipment cleaning, and industrial component processing. Monitoring results over 2–4 week periods revealed that the Mini-CEMS could effectively capture dynamic variations in adsorption performance and identify breakthrough behavior of activated carbon beds. The measured adsorption efficiency was strongly influenced by environmental parameters: high relative humidity significantly reduced removal efficiency, while temperatures exceeding approximately 40 °C caused partial desorption of previously adsorbed VOCs. In contrast, moderate temperatures and higher inlet VOC loading stabilized adsorption performance. The system also enabled practical operational diagnosis, such as determining optimal carbon replacement intervals and detecting abnormal performance caused by overheating or moisture interference. Compared with conventional regulatory monitoring instruments, the proposed Mini-CEMS provides a low-cost and continuous diagnostic tool for evaluating air pollution control equipment under real industrial operating conditions. This methodology offers a practical approach for manufacturers and regulators to optimize VOC mitigation strategies and improve environmental management.