Standardized evaluation and rating of biofilters. II. Manufacturer's and user's perspective

As manufacturers of biofilters we feel that it is important that our customers have a standardized set of criteria that can be used to compare the many different commercially available biofilters on the market today. The purpose of this paper is to show how a variety of manufacturers size their own filters, establish commonalities between the methods and suggest, to the engineering community, the needs of the industry that are required to develop a uniform sizing criteria. Similarities in sizing methodologies include standard information supplied by the consumer (system volume, feed rate, etc.) as well as those estimated by the manufacturer (TAN production, and hydraulic requirements). Differences in sizing methodology include the use of in situ nitrification and system flushing. From the various examples of biofilter sizing, it is clear that manufacturers use a sizing methodology based on either an areal or volumetric TAN conversion rate (ATR or VTR). As manufacturers, we should be able to publish ATR or VTR for each of three trophic levels (oligotrophic, mesotrophic and eutrophic) with appropriate correction factors for water temperature and salinity. A standardized labeling system that would allow system designers to accurately and rapidly determine which biofilter(s) meet their needs is proposed. We leave it to the engineering community to devise a standardized scheme by which VTR values could be determined to facilitate this comparison.