Monitoring temporal hazardous air pollutant gaseous generation in ethanol plants: An FTIR-based measurement...

Reliable, portable, and real-time measurements of Volatile Organic Compounds (VOCs) and Hazardous Air Pollutants (HAPs) from industrial ethanol fermentation remain a challenge due to the complex gas mixture in emissions, which includes high moisture content, elevated CO₂ concentrations, and trace gases at low concentrations. Conventional Continuous Emissions Monitoring Systems (CEMS) are typically installed downstream of air treatment units and therefore cannot capture source-specific emissions or temporal dynamics within fermentation units. To address these limitations, this study presents a portable, field-deployable methodology using Fourier Transform Infrared Spectroscopy (FTIR) for upstream, high-resolution monitoring of fermentation emissions. This method integrates commercially available instrumentation with a custom-designed dilution system and field procedures. This methodology enables high-resolution, continuous measurement of ethanol fermentation off-gases under industrial operating conditions and provides a practical approach to source-specific emissions monitoring for research, diagnosis, and optimization purposes. •Portable FTIR configured for continuous, source-specific measurement of multi-compound fermentation off-gases. •A nitrogen-based dilution system was developed to extend FTIR measurement capability to measure high- and low-concentration compounds simultaneously. •A field-ready sampling procedure suitable for industrial ethanol fermentation emissions monitoring and other complex emission sources.