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PATHOGEN EQUIVALENCY COMMITTEE (MCEARD)
SMITH, J. E., B. ACQUISTO, M. C. MECKES, D. S. BROWN, G. FOUT, R. BASTIAN, S. SCHAUB, AND F. W. SCHAEFER. PATHOGEN EQUIVALENCY COMMITTEE (MCEARD). Presented at WSWRD/NRMRL BOSC Review, Cincinnati, OH, January 25 - 27, 2006.
The objectives of this task are to:
MYP Science Question: What is the current state of management practices for biosolids production and application, and how can those be made more effective?
Research Questions: Are there innovative or alternative sludge disinfection processes that are capable of significantly reducing pathogens (Class B, Alternative 3) or further reducing pathogens (Class A, Alternative 6) and thus meeting the requirements of 40CFR503?
What must the developer of a new/emerging sludge disinfection process do to demonstrate the capability of his/her process? In other words, what pathogens or indicator organisms must it be capable of reducing?
Is the PEC using the best criteria to evaluate unproven technologies; are the best standardized and validated analytical methods being used for quantifying fecal coliform, Salmonella spp., enteric viruses, and Ascaris spp; and are pathogens emerging that Class B or A processes may not be able to disinfect
The U.S. Environmental Protection Agency created the PEC in 1985 to make recommendations to EPA and State managers on the equivalency of unproven sewage sludge disinfection technologies/processes to either a Process to Significantly Reduce Pathogens (PSRP) or a Process to Further Reduce Pathogens (PFRP) under the 40CFR-Part 257 and later 40CFR-Part 503 Regulations. The PEC consists of eleven members with expertise in bacteriology, virology, parasitology, wastewater engineering, medical and veterinarian sciences, statistics, and sludge regulations. It includes representatives from EPA's research and development, regional and water offices, and the Centers for Disease Control. Its members also provide guidance to applicants with new technologies on the data necessary to determine equivalency, and to permitting authorities and members of the regulated community on issues related to meeting the pathogen and vector attraction reduction requirements of Part 503. Since 1989 the PEC has authored, made available and updated every three to four years the so called White House Document (Environmental Regulations and Technology: Control of Pathogens and Vector Attraction in Sewage Sludge). It is a primary reference for regional, state and local regulatory authorities and their constituents. In addition to providing information on Class A and B processes and vector attraction reduction options, it clarifies many sampling, monitoring and analytical issues. Detail is given on applying for PSRP or PFRP equivalency.
Through deliberations on PSRP and PFRP applications, helping to put in place Quality Assurance Project Plans (QAPPs) for demonstrating equivalencies, overseeing demonstrations, and holding workshops with invited international experts, the PEC maintains an awareness of emerging pathogen, analytical method, disinfection, and risk analysis issues. In addition it is always looking for ways to improve its process evaluation criteria. A report, Contemporary Perspectives on Infectious Disease Agents in Sewage Sludge and Manure, was recently prepared and made available by the PEC. It addresses such issues as temperature tolerances of emerging or re-emerging pathogens, and appropriate indicators of effective pathogen treatment. Within the year the PEC met with a group of international experts on disinfection approaches for sewage sludge. They suggested the PEC consider how many stressors are involved when evaluating new technologies; thinking in terms of the benefit of multiple barriers. Secondly, the PEC needs to consider the effect of a proposed disinfection method on parasites, viruses, and bacteria.
The PEC is in the process of establishing a website to help applicants in submitting an application for a process proposed to be equivalent to a PFRP or PSRP. Since its creation the PEC has evaluated numerous sludge disinfection technologies/processes and recommended 13 for equivalency. New ideas for novel processes are brought to the PEC's attention at a steady pace of approximately 20-30 per year, although equivalency is not sought in all cases. An equivalency application is followed through successfully to a final recommendation at an average of one per year. Examples of equivalencies recently recommended by the PEC include an anaerobic digestion system that is unique in that it combines a thermophilic digester with a mesophilic digester for a two-phase system; a flow-through thermophilic treatment process which is significant because it is the first approved process to use continuously fed, mixed digester; and a process which achieves disinfection from contact with ammonia and elevated pressure and temperature in a plug-flow reactor. There are currently six innovative processes actively seeking equivalency including processes such as vermicomposting, and an acid-oxidative process using chlorine dioxide.
Impact and Outcomes
The PEC directly assists federal, state, and local regulatory officials by overseeing the testing of new biological, physical and chemical technologies for reducing pathogens. It thus gives utilities more alternatives for disinfecting sludges and helps to assure the public that the new processes are effective. The PEC?s equivalency recommendation process is an outlet for potentially more cost-effective sewage sludge treatment processes to become accepted under the current 40CFR503 regulations while still ensuring that any potential human health risk minimized.