Depletion of hormones and antimicrobials in cattle manure using thermophilic anaerobic digestion

BACKGROUNDThe fate and effect of hormone and antimicrobial residues in the manure of therapeutically treated cattle is of considerable concern because of the adverse effects of environmental loading of these chemicals. The objective of this study was to determine the depletion of tylosin (TYL), chlortetracycline (CTC), sulfamethazine (SMZ) and megestrol (MEG) using thermophilic anaerobic digestion (TAD). RESULTSQuantitative methods using HPLC-DAD-MS/MS analysis were developed to monitor the hormone and antimicrobials, spiked into manure obtained from unmedicated cattle. These manure samples were incubated for a 28-day period, during which hormone and antimicrobial depletion, and biogas production, was determined. Significant depletion of TYL, CTC, SMZ and MEG was demonstrated using TAD. Both TYL and CTC underwent complete depletion, while SMZ and MEG were each 80% depleted by the 28th day of incubation. The presence of antimicrobials had no negative effects on process stability and caused no significant reduction in total methane production. CONCLUSIONThis process has demonstrated value in reducing the hormone and antimicrobial load to the environment, while not compromising economic value of the biogas production, and allowing use of post-digested biosolids as a regenerated fertilizer. (c) 2015 Society of Chemical Industry