The Effects of Antibiotics on Methane Generation from the Anaerobic Digestion of Swine Waste

Antibiotics are used for the growth promotion and treating infections in livestock. Not all whole portion of antibiotics fed to animals is absorbed in their guts, and the unabsorbed these antibiotics present in their feces and products in trace quantities. During the anaerobic digestion of the animal waste, these antibiotics will affect the production of gas and quality of methane. This research is focused on the comparison of the effect of antibiotics from three classes namely- macrolide, sulfonamide and tetracycline. Methane and carbon dioxide gases were analyzed from the captured gases. The gas quality was analyzed by using gas chromatography. Total three different levels of concentration- 4 mg/L, 20mg/L and 132mg/L of antibiotics were studied in three separate set of experiments. Waste samples were spiked with a known concentration of antibiotics prior to the digestion. The gas quality in treated digesters was compared to that of untreated digesters to observe the effect of antibiotics on the anaerobic digestion process. The effect of antibiotics was not observed significant in either of concentrations. The quantities of methane and carbon dioxide are presented and compared between treatments