Abstract
Biotrickling filter (BTF) technology has become a widely accepted and preferred technology for the elimination of odors originating from municipal wastewater treatment plants and collection systems. It is capable of reliable and efficient odor removal, and can be more cost effective and environmentally friendly compared to conventional air pollution control technologies such as biofilters, physical-chemical, or adsorptive technologies. Despite the widespread use of BTFs for municipal odor control, there is still ample room to improve the technology. In particular, BTFs are considered to be very effective in removing inorganic odors, but its ability to remove organic odors is sometimes questioned. This paper reviews the deficiencies in the current BTF science and provides suggestions for further research on how it could be improved to effectively and reliably remove most, if not all, municipal odors to regulated levels.
BTF technology is most often treated as a “black box” and little is known about the complex combination of different physical-chemical and biological phenomena comprising the process. To improve the technology, it is essential that the fundamental mechanisms involved in odor removal be well understood. Key issues such as microbial biofilm architecture and ecology, media characteristics, mechanisms of mass transfer, and control of process conditions warrant further research in order to optimize the technology.
Molecular fingerprinting techniques such as terminal-restriction fragment length polymorphism (T-RFLP) could be used to characterize microbial populations in bioreactors, thus leading to a better understanding of which bacteria are present and their role in the oxidation of inorganic and organic odorous compounds. The use of scanning electron microscopy could provide insight into the biofilm architecture and bacterial morphology. The microbial ecology of a full scale BTF was evaluated using T-RFLP. The results show that T-RFLP can be an effective tool to further the understanding of the complex microbial ecology inside BTFs. Ultimately, such understanding can result in smaller, more efficient biotrickling reactors that effectively remove both inorganic and organic odors.
Keywords: BTFs, biological odor control, organic odor removal
