|ASHWORTH, DANIEL - University Of California
|Ibekwe, Abasiofiok - Mark
Submitted to: Journal of Environmental Chemical Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2020
Publication Date: 6/22/2020
Citation: Ashworth, D.J., Ibekwe, A.M. 2020. System of multi-layered environmental media for the removal of antibiotics from wastewater. Journal of Environmental Chemical Engineering. 8(5). https://doi.org/10.1016/j.jece.2020.104206.
Interpretive Summary: Due to widespread use of antimicrobials, land application of animal manure, biosolids, and wastewater can result in the contamination of soil and water resources and facilitate the dissemination of antibiotic resistance genes in the environment. In this study, we designed and tested a system of layered environmental media consisting of gravel, sand, soil, and biochar to determine the removal efficiencies of four antibiotics: amoxicillin, cefalexin, sulfadiazine, and tetracycline. The system was most efficient in the removal of tetracycline, followed by cefalexin, amoxicillin, and sulfadiazine. The results indicate the importance of using layers of different media and different hydraulic retention times to target the removal efficiencies of different antibiotics. This research will benefit scientists and health officials seeking agricultural and waste disposal practices the minimize the spread of antibiotic resistance in the environment.
Technical Abstract: In relation to the dissemination of antibiotic resistance in the environment, strategies to remove antibiotics from wastewater are urgently required. As such, we designed and tested a system of layered environmental media (consisting of gravel, sand, soil, and soil+biochar) through which antibiotic-laden water was pumped. The removal efficiency of the system was assessed. Overall removal efficiencies of the antibiotics amoxicillin, cefalexin, sulfadiazine, and tetracycline were 81, 91, 51, and 98%, respectively. Amoxicillin and cefalexin removal was largely controlled by chemical degradation within the gravel layer, whereas sulfadiazine was largely removed via both chemical and microbial degradation in the soil+biochar layer and tetracycline was lost via hydrolysis reactions in the gravel layer. The results indicate the importance of using layers of different media to target different compounds. Increasing the hydraulic retention time of the system improved removal efficiency, especially for amoxicillin and cefalexin, which had half-lives that were much shorter than the hydraulic retention time. The presence of dissolved humic acid in the influent water generally reduced antibiotic removal efficiency. Overall, the results indicate the potential of the system for antibiotic removal from water and highlight ways in which improvements to removal efficacy may be achieved.