Effect of Media Fill Ratio and Hydraulic Retention Time on Suspended Particle-Attached Growth Fermenter Performance

ABSTRACT SUSPENDED particle-attached growth (SPAG) anaerobic fermenters were evaluated to determine optimum design parameters. The effects of media fill-ratio (FR) and hydraulic retention time (HRT) were evaluated using the liquid fraction of screened-flushed swine waste as a methane substrate. The study was conducted using 100 micron polypropylene felt suspended in replicated 25 L fermenters. PR's of 0%, 7.5%, 15%, and 30% were tested at HRTs of 5,3,2 and 1 day. A 300 L continuously stirred tank reactor (CSTR) served as the control for this experiment. Volatile solids (VS) concentration of the influent ranged from approximately 9 to 22 g VS/L over the course of the 12 month study. Results indicate that, in this study, optimum methane production is achieved at a 2 day nominal HRT with an FR of 7.5%.