Effects of tylocin on room anaerobic digestion of swine sewage

Veterinary drug residue in the sewage is one of the most important factors which impacts the effect of anaerobic digestion. Effects of tylosin on anaerobic digestion of swine wastewater at two concentration levels were studied by two methods as adding swine manure collected from swine fed with tylosin in diets and adding tylosin into antibiotic free swine manure. Anaerobic digestion experiments were conducted at 20°C in laboratory digesters which the effective volume was 1300 mL. The results showed that the parent material of tylosin was not detected in the anaerobic digestion during the experimental period after seven consecutive days of adding tylosin at a rate of 7.42 μg/g and 12.96 μg/g respectively. Compared with the control, the presence of tylosin in swine manure enhanced methane production by 24.6% averagely. The trials adding tylosin at the concentration of 7.42 μg/g swine manure produced more methane than that of 12.96 μg/g. But there were no significantly difference between two methods. The NH 4 +-N concentration in trials adding swine manure collected from swine fed with tylosin in diets was significantly higher than that in the trials adding tylosin into antibiotic free swine manure. But there were no significantly difference between two adding concentrations of tylosin. Compared with the control, the trial with addition of tylosin had no significant effect on the pH, TN, COD of biogas slurry, and TN, organic matter of biogas sludge. Under the condition recommended by this article, it was observed that the presence of tylosin with the concentration of 7.42 μg/g and 12.96 μg/g swine manure had no negative effect on anaerobic digestion of swine sewage, and two methods suited for studying the effect of tylosin on anaerobic digestion.