Compliance outlook: meeting 40 CFR part 503, class B pathogen reduction criteria with anaerobic digestion

The current federal sludge regulations for the first time place limitations on the concentration of pathogens or indicator organisms in sludge and sludge products destined for distribution and marketing and land application. However, there is a general lack of data for assessing the impacts of these new limits on the wastewater industry. To understand better the extent of the compliance problem and the factors that may enable publicly owned treatment works (POTWs) using anaerobic digestion to comply with the new criteria, a survey of treatment plants around the U.S. was undertaken. In addition to data on fecal coliform densities in raw and digested sludge, information was collected on the design and operating characteristics of the 54 digestion facilities that participated in the survey. Based on the analysis of survey responses, it appears that the pathogen reduction criteria under the regulations are not unreasonable and should be achievable by most conventional anaerobic digestion facilities.