EFFECTS OF ANAEROBIC DIGESTION AND SEPARATION OF PIG SLURRY ON ODOR EMISSION

Storage and land application of livestock manure causes considerable odor nuisance to the surrounding neighborhood. Anaerobic digestion and separation of slurry change composition and physical properties of slurry and may therefore lessen the odor pollution during storage and land application. An experiment was set up to study the effects of anaerobic digestion and separation of slurry on the emission of odor. Odor concentration above treated and untreated slurry was compared during storage and following land application. Concentrations of odorous gasses were measured using GC/MS analysis and odor concentrations were determined using dynamic dilution olfactometry. Slurry concentrations of malodorous volatile fatty acids were reduced by between 79% and 97% by anaerobic digestion, while concentrations of malodorous phenolic and indolic odor components above the slurry were reduced by both anaerobic digestion and subsequent separation. Odor concentration in air sampled above slurry stores was slightly reduced by anaerobic digestion; however, odor concentration was found to be higher above stores of anaerobically digested slurry following mixing of the slurry prior to land application. Odor concentration in air sampled above land applied slurry was reduced by 17% by anaerobic digestion and by 50% by combined anaerobic digestion and separation.