Reduction of Bacterial Pathogens in a Single-Stage Steel Biodigester Co-Digesting Saw Dust and Pig Manure at Psychrophilic Temperature

The experiment was conducted using a single-stage steel biodigester of 75 L working volume, charged with 75% pig manure and 25% pine wood sawdust operated under batch mode at psychrophilic temperature range (13.16–24.69 °C). total viable count determined via the spread plate method on selective microbiological media to determine numbers selected bacterial pathogens in samples collected from biodigesting chamber every seven or fourteen days over duration study. Multiple linear regression models including log counts (response) number days, pH, average daily as predictors were developed Matlab for each bacterium. reduction (90–99.9%) isolates E. coli, Salmonella, Yersinia, Campylobacter, Listeria varied time (days) their initial respective 2 × 106, 7 104, 3 105, 9 1 104 cfu/g concentrations lower than detection limit (DL = 102 substrate). coli demonstrated least resistance environmental conditions survived only 77 unlike L. monocytogenes that lasted 175 most resistant From models, directly inversely related counts, respectively, contrary others. predictors, temperature, described either primary secondary factors based bacteria reliefF test.