Comparison of Concurrent Pilot Scale and Full Scale Batch Operations to Demonstrate Disinfection

The Neutralizer® process is a sludge disinfection process which has recently been granted National PFRP equivalency recommendation by the USEPA's Pathogen Equivalency Committee (PEC). During the course of preparing an application to the EPA for regulatory approval a substantial amount of process development and testing was conducted at lab scale, pilot scale and full scale.During the later stages of development and testing, the need arose to add quantities of polioviruses and Ascaris suum, which are pathogenic microorganisms (pathogens), to the raw sludges. This was necessary to demonstrate reduction of viable Helminth ova and enteric virus. In order to avoid adding the pathogens to the full scale batch process tanks, a method was developed whereby matrix, untreated sludge, spikes were conducted at pilot scale only. The spiked pilot scale process was operated concurrent with and under identical conditions to the full scale batch process and the resulting reduction of indicator organisms and surrogate indicator organisms was compared between the two processes. Compliance with the pathogen reduction requirements of the PEC was established by demonstrating that the sludge in both the full scale and pilot scale process tanks was subjected to identical conditions, and that the reduction of both indicator and surrogate indicator organisms in both process tanks were the same.