THE EVOLUTION OF BIOFILTRATION AND THE APPLICATION OF THIRD GENERATION DESIGNS

The pioneers of odor control biofilters were the municipal wastewater department employees who were on the front line of odor complaints. As a result of the continuous encroachment of wastewater pump stations and treatment plants by residential and commercial development odor complaints have increased. This has put pressure on municipalities to find effective and cost-effective odor control devices and led to the investigation of the various odor treatment technologies. Biofilters were not recognized in the United States as a viable alternative fifteen years ago, and designs coming from Europe seemed either oversimplified or very complex. These early biofilter designs were enhanced and adapted to the needs of the municipal wastewater industry. The success of the early “homemade” designs caught the attention of commercial and research interests and biofilters evolved. This paper discusses the design and implementation of biofiltration at critical stages in the development process utilizing actual site studies and empirical data to support the discussion. The discussion begins with the first generation biofilters that were built in the ground without an air pretreatment (humidification) or a moisturization system. Second generation biofilters are discussed relative to the control options selected and the relative success of those attempts. Third generation biofilters diverge from compost-based media that was considered standard with the preceding designs. Third generation designs certainly approach a reactor type of system and the ramifications of this step are discussed.