Treating high loads of ethyl acetate and toluene in a biofilter
- Univ. of California, Riverside, CA (United States). Coll. of Engineering
- 3M Environmental Technology and Services, St. Paul, MN (United States)
- Gero Leson Environmental Consulting, Berkeley, CA (United States)
In the past, biofilters have primarily controlled dilute, usually odorous, off-gases with VOC concentrations < 1 g/m{sup 3} and VOC loads < 50 g/m{sup 3}h. Yet, US industry has also shown an interest in the removal of higher concentrations of VOC and hazardous air pollutants (HAP). In two such instances, the treatment of high loads of ethanol from a foundry and a bakery, respectively, caused degradation limitation, the formation of odorous acetic acid, and problems maintaining the proper moisture content because of the exothermic nature of the biodegradation process. For a more detailed study of the behavior of biofilters at high loads of binary VOC mixtures, two bench-scale biofilters were operated using a commercially available media and a mixture of wood chips and compost. Both were exposed to various high loads of mixtures of ethyl acetate and toluene. Concentration profiles and the corresponding elimination vs. load curves were established through frequent grab-sampling and GC analysis. Biofilter response to two frequently encountered operating problems, i.e. media dry-out and temperatures exceeding 40 C, was also evaluated under controlled conditions. Resident microbial populations were characterized to assure the presence of organisms capable of degrading both major off-gas constituents. The results demonstrated several characteristics of high-load biofilters: maximum elimination capacities for ethyl acetate were typically limited to 200 g/m3h; despite the presence of toluene degraders, the removal of toluene was inhibited by high loads of ethyl acetate; several by-products, particularly ethanol, were formed; and short-term dry-out and temperature excursions resulted in reduced performance. The paper discusses these observations in more detail. Its findings provide a quantitative assessment of some of the limitations of biofilters used for the treatment of high VOC loads.
- OSTI ID:
- 351109
- Report Number(s):
- CONF-970677--
- Country of Publication:
- United States
- Language:
- English
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