TEMPERATURE & HRT STRESS TESTS AND THE RELATION TO MERCAPTAN LEVELS; HYPERION'S ADVANCED THERMOPHILIC ANAEROBIC DIGESTION PILOT FACILITY'S CONTINUED PILOT PROGRAM

Abstract

In 1999, the Environmental Engineering Division (EED), Bureau of Engineering, City of Los Angeles, designed and constructed a pilot facility at the Hyperion Treatment Plant. The purpose of the facility was to pilot test various advanced digestion scenarios in an effort to advance the digestion process at the Hyperion Treatment Plant. The outstanding feature of the facility is that it thoroughly removes itself from the typical bench scale testing approach by offering full-scale data under real plant conditions without risk to the plant's full scale solids processing system and it activities.The Hyperion Treatment Plant's solids handling processing was converted to Class A Biosolids production in 2002. This conversion has brought forth some interesting queries with regard to temperature and hydraulic retention time as they relate to the time/temperature regime. Two studies were completed to address those queries; a Temperature Stress test and a Hydraulic Retention Time Stress test. As the results of these studies have already been reported, the pilot facility continued these studies as they would related to a more recent difficulty, odors. In the early stages of conversion, Hyperion experienced very high odor levels due to mercaptan concentrations in the off gas. The previous tests and their current setup provided available digestion scenarios as the means to investigate the phenomena. Digester temperature was carefully controlled and performance closely monitored. Again, the observations from these studies will be a part of this paper where data indicates mercaptan levels to decrease with control of temperature.