Water Environment Federation (WEF)

From concept to equivalency: getting your innovative sludge disinfection process classified as A or B is now less of a mystery

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Courtesy of Courtesy of Water Environment Federation (WEF)

The Pathogen Equivalency Committee has updated the criteria it uses to make recommendations of equivalency on innovative or alternative sludge pathogen reduction processes. To assist new applicants through the equivalency recommendation process the pathogen equivalency committee has rolled out a new website. The Pathogen Equivalency Committee website clearly presents the criteria used for equivalency and provides guidance for developing the proper testing and documentation. The main steps of the equivalency recommendation process are discussed through the introduction of the website materials. A hypothetical case study is presented to demonstrate use of the website and some key points in developing an application for equivalency to a process to further reduce pathogens.


Originally under 40 CFR Part 257 and now under 40 CFR Part 503, one of the accepted options for treating sewage sludge before applying it to land is to use a process that is equivalent to the specifically listed processes to significantly or further reduce pathogens. In 1985 the U.S. Environmental Protection Agency (U.S. EPA) created the Pathogen Equivalency Committee (PEC) to oversee this equivalent process option by providing guidance and making recommendations on process equivalency to the permitting authorities at the federal and state levels. Since its inception, the PEC has reviewed numerous applications and recommended processes for equivalency to processes to significantly reduce pathogens (PSRPs) which meet Class B pathogen reduction requirements or processes to further reduce pathogens (PFRPs) which meet Class A pathogen requirements. The PEC’s approach to equivalency recommendations evolved over this time. There was a degree of flexibility in the way each application was treated. The differences in review were typically an artifact of the wide variety of process types being considered. Still, these differences may be construed as unequal treatment. Further, over 20 years have passed since the PEC conceived of their equivalency requirements. Since that time negative public perception of the land application of biosolids has grown and the PEC is facing increased scrutiny.

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