Biofiltration of simulated air pollutants from distillers dried grains with solubles (DDGS) dryer vents at corn‐derived ethanol production facilities

Abstract

AbstractThe DDGS dryer vents at corn‐derived ethanol production facilities often contain a mixture of odorous and/or potentially hazardous air pollutants including acetaldehyde and formaldehyde. The objective of this study was to investigate the feasibility of utilizing a biofilter system to treat the volatile organic compounds (VOCs) released from the DDGS dryer stack during ethanol production. Single aldehyde elimination capacity experiments indicate that both acetaldehyde and formaldehyde are readily biodegraded in a biofilter at a short contact time of 10 s, although the acetaldehyde removals during the initial start up period were lower than those observed during later operation. A biofilter packed with porous silicate pellets at neutral pH successfully achieved greater than 90% removal of VOC mixtures containing acetaldehyde, formaldehyde, ethanol, and acetic acid. However, extended operation with the four component VOC mixture led to a decline in biofilter pH. At low pH (4.6), acetaldehyde removal declined from 95 to 62% and ethanol removal declined from 90 to 57%. The option of utilizing a water scrubber upstream of the biofilter to remove acetic acid was investigated; it was determined that effective acetic acid removal was possible in a recirculating water scrubber maintained at a pH level above ∼7, where the rate of removal was controlled by gas phase mass transfer resistance. © 2009 American Institute of Chemical Engineers Environ Prog, 2010