The Incredible Shrinking Biofilter – Case Studies in Odor Control

Many objectionable odors are airborne intermediates from the partial degradation of organic materials. In a biofilter, the microbes complete the degradation, using the offensive organics as a food source and eliminating the odor. The byproducts of this biooxidation process are primarily carbon dioxide and water vapor. Biofiltration is not new for odor control, especially in Europe. However, advancements in engineered biofilters have reduced their size and cost significantly. Biofilters are effective controls for odor sources such as sewage lift stations and treatment plants, food processing, rendering, confined animal operations, and much more.Many municipalities face challenges with odors from sewage collection or treatment facilities. Frequently, odorous lift stations must be located near housing areas where local residents are negatively affected. Additionally, many treatment facilities have suffered encroachment by housing or businesses locating closer and closer, until odors have become a problem. For collection systems in particular, hydrogen sulfide (H2S) is a common odor source. Biofilters are also effective in treating H2S in a variety of situations, such as at this lift station in Portland, Oregon, shown in Figure 1.This paper will discuss recent advancements in engineered biofilters for odor and VOC control, including conditioning of the airstream and the use of a structured organic-based media to significantly reduce the footprint of the biofilter. Case studies will include odor control at lift stations, animal rendering facilities, and solvents in industrial settings.