Load Dampening System for Vapor Phase Bioreactors

Vapor phase bioreactors are receiving increasing attention as a cost-effective treatment method for air contaminated with volatile organic compounds (VOCs). In this study, a novel absorption and humidification system was evaluated for its ability to dampen transient VOC loads, and to reduce their detrimental effects on a downstream bioreactor. A model based on the mass transfer characteristics of two target compounds (acetone and toluene) was developed and takes into account a closed water recirculation loop that minimizes fugitive emissions and simultaneously humidifies the inlet gas stream. When water is used as the scrubbing liquid, model and experimental results indicate that the system effectively dampens hydrophilic compounds and segregates them from the hydrophobic compounds in the waste gas stream. The response of a vapor phase bioreactor to the pretreated stream has also been assessed, and results indicate that the load dampening system works effectively for hydrophilic, but not hydrophobic, VOCs. However, when an organic cosolvent is used in conjunction with water, hydrophobic VOCs can also be dampened efficiently.