Effect of two different sulfamethazine addition methods on psychrophilic anaerobic digestion of swine wastewater

Abstract

Veterinary antibiotic residue in manure is one of the most important factors which have an impact on the anaerobic digestion. This article studied the effect of sulfamethazine (SM-2) on psychrophilic anaerobic digestion of swine manure by two adding methods, addition of manure from swine fed with SM-2 in diet and direct addition of SM-2 with blank manure, under two adding concentrations of SM-2 (2.38 and 1.24 mg/g dry swine manure). Anaerobic digestion experiment was conducted at 20 °C in laboratory digesters with the effective working volume of 1.3 L. Methane production of each digester was measured by displacement method daily. Grad samples were collected to determine the concentration of SM-2, pH, chemical oxygen demand (COD) in slurry and organic matter in biogas residue. The results showed that the concentration of SM-2 in anaerobic system fed with manure containing SM-2 was lower than that fed with blank manure and SM-2 under the same addition of SM-2 and the degradation rate of SM-2 in the high concentration treatment was faster than that in the low concentration treatment. Compared with the control group, the treatments added with SM-2 had no significant difference in methane production, COD in slurry and organic matter in biogas residue, but adding SM-2 and blank manure improved pH of swine slurry in SM-2 adding period. Due to the different degradation rate of SM-2 in anaerobic digestion between the two adding methods of SM-2, using manure collect from animals administered with SM-2 is more appropriate to assess the effect of SM-2 on anaerobic digestion.