Dielectric barrier discharge plasma system for sterilizing exhaust gas from microbial fermentation processes

ABSTRACT 2 2 Abbreviations: DBD: dielectric barrier discharge; GMM: genetically modified microorganism; HEPA: high-efficiency particulate air; IGBT: insulated gate bipolar transistor; STS: stainless steel; PC: polycarbonate; LB: Luria-Bertani; YPD: yeast extract peptone dextrose Sterilizing exhaust gases in industrial fermentation, especially those using genetically modified microorganisms, poses significant biosafety challenges that require effective and cost-efficient solutions. This research methodically enhanced a dielectric barrier discharge (DBD) plasma system for treating fermentation exhaust. We developed three iterations: the first was a prototype that proved conceptually viable but exhibited limited flow capacity. The second version improved stability via electrode reconfiguration, although it faced airflow distribution limitations. The final model featured shortened electrodes, vertical alignment, thinner ceramics, and broader fluid pathways, resulting in enhanced discharge uniformity and power efficiency. The optimized system incorporated three modular reactors (90 cm × 60 cm × 150 cm) alongside a condenser and wet scrubber for complete treatment. Testing with Escherichia coli , Corynebacterium glutamicum , and Saccharomyces cerevisiae achieved 100% sterilization efficiency over 8–24 h of continuous operation at a flow rate of 3,000 L/min, consuming only 0.8 kW of power per module. This modular design provides operational flexibility, requires minimal maintenance, and ensures scalability across various fermentation sizes. We present both a viable industrial bioprocessing solution and foundational design guidelines for scaling plasma technologies, thereby enabling the sterilization of genetically modified microorganisms in line with increasingly stringent environmental regulations.