Antibiotic Sorption to Dairy Manure in Laboratory Batch Experiments

Veterinary pharmaceuticals have recently attracted attention in manure management systems, increasing the complexity of best management practices that should be considered to address manure pollution. Movement a focus on phosphorus and nitrogen to emerging contaminants complicates the removal mechanisms that must be considered. The sorption dynamics of pharmaceuticals must be well understood before we begin engineering systems to remove these biologically active compounds. This work investigates the sorption of erythromycin and ampicillin to dairy manure. Erythromycin is more environmentally stable, though both have been identified as antibiotics with potentially important impacts on human health. These two antibiotics were chosen because of their differing classes and structural make up. Using UV spectrophotometry, sorption isotherms were calculated to generate distribution coefficient relationships. These antibiotics sorb strongly to organic matter, indicating manure management practices that reduce transport of manure and associated sediments may reduce the transport of antibiotics as well. This work focuses on the parent compounds and not their metabolites, though we recognize the metabolites may also be biologically active compounds.