ACHIEVING CLASS A BIOSOLIDS WITH SQUEEZE PRESSURE, VACUUM PRESSURE, TIME AND TEMPERATURE
Abstract:Innovative technologies combining dewatering and drying in one device are becoming attractive in municipal biosolids and residuals processing. One technology is J-Vap®, which is drying the solids using heated water while under pressure and applying vacuum to the filtrate. The objective of this study was to demonstrate that the squeezing pressure combined with negative vacuum pressure and temperature increase would lead to pathogen inactivation without necessarily meeting the time/temperature requirements set in the USEPA Part 503 requirements for pasteurization. The paper presents pilot scale results from experiments on a prototype of the technology. Anaerobically digested biosolids from a full scale conventional activated sludge plant, were spiked with pathogens or pathogen indicator organisms, such that the process could be approved by the U.S. EPA's Pathogen Equivalency Committee (PEC) as a process that produces Class A biosolids. The spikes included both viruses and helminth eggs. Operating parameters were monitored to determine the conditions that could lead to pathogen disinfection.
Results showed that Class A biosolids are achieved when the process is ran under typical operating conditions, and where the monitored solids temperature was maintained at above 50°C for over 3 hours. Additional types of biosolids or residuals that have undergone different wastewater treatment processes must be tested to obtain national certification and to assure validation of the disinfection.
Document Type: Research Article
Publication date: January 1, 2005
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