Impact of Treatment Temperature Decline on Stability of Advanced Alkaline Biosolids

Biosolids must be stabilized in order to reduce odors, which have been noted as a major concern with respect to alkaline stabilization. Stabilization is designed to address potential putrefaction processes, odiferous releases and vector attraction concerns. Also, most alkaline processes are open systems in which temperature and mixing are more difficult to control, and factors such as increased pressure or bactericidal action of un-ionized ammonia are not present to aid in disinfection. The purpose of this project was to begin assessment of the long-term stability of an advanced alkaline product resulting from operating conditions established by testing previously conducted and approved by EPA’s Pathogen Equivalency Committee. The conditions formerly established as optimum to achieve required pathogen destruction resulted in the ability of advanced alkaline system to operate at a lower temperature of 55 oC as opposed to the temperature of 70oC required by the U.S. EPA 40CFR Part 503 Final Rule Standards for the Use or Disposal of Sewage Sludge. All previous data collected regarding the ability of the advanced alkaline product to remain stabilized over long periods of time were related to the material produced at the higher temperatures which indicated no significant decline in pH over a time of 5 years.The goal of this research is to obtain better understanding of the stabilization of biosolids over time, lower costs, reduce odor formation and to reduce vector and pathogen attraction so to comply with the current requirements.