Low-Cost, Low-Tech Biosolids Treatment via Long-Term Storage: A Comparison of Two Pilot-Scale Studies

摘要

Many water resource recovery facilities (WRRFs) across the U.S. are seeking to upgrade to Class A biosolids production as a means for improving public acceptance of biosolids land application and opening additional avenues for their distribution. However, the vast majority of U.S. WRRFs serve small- or mid-sized communities that lack the resources to implement the methods currently approved by the EPA for producing Class A biosolids, which are generally high-cost and high-tech and include the Processes to Further Reduce Pathogens (PFRPs). As a result, there is a growing need for low-cost, low-tech (LCLT) treatment options for Class A biosolids production. The overall goal of this multi-phase project is to develop a rational and universal approach for the design of LCLT Class A biosolids treatment processes. This paper focuses on comparing the key process parameters and pathogen and indicator organism (PIO) inactivation during parallel pilot-scale studies simulating LCLT biosolids treatment via long-term storage that were performed over one year at two similar WRRFs. The trends in key environmental conditions, physical/chemical parameters, and PIOs were very similar between the two test locations, demonstrating the potential for obtaining reproducible and predictable outcomes using LCLT treatment processes in different locations. One year of high-solids storage was adequate for meeting Class A and PFRP equivalency requirements for fecal coliforms, but the pilot-scale conditions, in which temperatures primarily were < 25 ℃, were not adequate for achieving the PFRP equivalency requirement for reduction of viable helminth ova. The effect of an additional year of long-term storage on viable helminth ova is being tested.