Use of antibiotics is common practice in agriculture; however, they can be released into the environment, potentially causing antimicrobial resistance. Naturally mined diatomaceous earth with bentonite was tested as a remediation material for tylosin, chlortetracycline, and ceftiofur in wastewater from a beef cattle feedlot. Langmuir binding affinity in 10 mM sodium phosphate buffer at pH 6.7 was established prior to testing wastewater to determine binding potential. Chlortetracycline was found to have a binding affinity of 15.2 mM-1 and a binding capacity of 123 mg per g of diatomaceous earth while ceftiofur showed a much lower binding affinity and loading at 7.8 mM-1 and 3 mg per g of diatomaceous earth, respectively. From spiked wastewater, tylosin (50 μg mL-1, pH 8) and chlortetracycline (300 μg mL-1, pH 6) were removed (100 and 80%, respectively) when treated with 20 mg of diatomaceous earth while ceftiofur (300 μg mL-1, pH 8) remained in solution. When the spiked wastewater was flocculated with aluminum sulfate, a change in pH from 8 to 4 was observed, and chlortetracycline was removed from the wastewater; tylosin and ceftiofur remained in solution. When subsequently treated with diatomaceous earth, ceftiofur and tylosin were completely removed by diatomaceous earth from the flocculated wastewater.
Not subject to U.S. Copyright. Published 2024 by American Chemical Society.