A model for an economical filter system that can remove antibiotics from wastewater has been designed by Agricultural Research Service (ARS) and University of California-Riverside (UCR) collaborators.
Microbiologist Mark Ibekwe with the ARS Agricultural Water Efficiency and Salinity Research Unit in Riverside, California, and UCR soil chemist Daniel Ashworth constructed the prototype system using four layers of natural materials: gravel, sand, soil, and biochar in a column 50-cm tall and 12-cm diameter.
They used the laboratory-scale model to remove four antibiotics: amoxicillin, cefalexin, sulfadiazine, and tetracycline at various levels of efficiency. These four antibiotics were selected for testing in the scale model because they are among the most common in wastewater treatment plant effluent. Conventional wastewater treatment plant systems are relatively effective at removing nutrients and bacteria but can be somewhat ineffective at removing antibiotics.
The effectiveness of the laboratory-scale system varied with the antibiotic being evaluated. It successfully removed 98 percent of the tetracycline, followed by 91 percent of cefalexin, 81 percent of amoxicillin and 51 percent of sulfadiazine. The antibiotics had initial concentrations of 10 ppb, comparable to levels that have been seen in municipal wastewater.