Bacterra™ by Filterra® Advanced Bioretention System Discussion of the Benefits, Mechanisms and Efficiencies for Bacteria Removal
International Low Impact Development Conference , 2008
Coffman, L., Ruby, M.
With the growing concern about bacterial impairment of recreational waters associated with stormwater runoff, extensive laboratory and field studies were conducted by Filterra®, division of Americast, Inc., to determine an optimum blend for bacteria removal. The Filterra® bioretention BMP blend is currently designed to utilize physical, chemical and biological pollutant mechanisms to remove typical stormwater pollutants such as TSS, phosphorus, nitrogen and heavy metals. Filterra® has developed a specialized treatment media to remove fecal coliform and other pathogens from urban stormwater runoff. This new media blend has been trade marked Bacterra. Laboratory tests have shown bacteria removal rates between 77% and 99%, with preliminary field results showing removal between 94% and 99%. It is believed that the media goes through a maturation process where it develops a complex microbiological ecosystem that enhances predation, capture and destruction of fecal coliform. Physical, chemical and biological processes are all believed to contribute to the removal process, but sorption is believed to be the primary capturing mechanism. This study showed that high bacteria removal rates of over 90% were achieved at extremely high flow rates at 100 inches per hour. This study does not support conventional thinking that slow flow rates and long contact times are needed to effectively remove bacteria from stormwater runoff using bioretention media. This paper summarizes the research effort and findings of Filterra® in the development of their Bacterra™ high flow bioretention media treatment technology.