Removal of antibiotics from anaerobically digested biosolids via synergistic release using ethylenediaminetetraacetic acid disodium salt dihydrate and sodium persulfate oxidation.

Large-scale anaerobic treatment involves a high risk of antibiotic pollution in anaerobically digested (AD) biosolids, which hinders the efficient utilization of farmland AD biosolids. Herein, a process for the in situ removal of antibiotics from AD biosolids using ethylenediaminetetraacetic acid disodium salt dihydrate as the release agent synergized with sodium persulfate oxidation is reported. The developed process was used to remove antibiotics from actual AD biosolids. The release and removal efficiency of 21 antibiotics (including tetracyclines, quinolones, and sulfonamides) were studied. A concentration of 10 mg g-1 release agent at pH 3 and 1 h oscillation time exhibited a 72.6 % average release efficiency of antibiotics from AD biosolids. Sodium persulfate with a concentration of 20 mg g-1 and 4 h oscillation time exhibited a 59.1 % average removal efficiency of pollutants from the supernatant. The pH rapidly increased during the release from solids and gradually decreased during oxidation. The dissolved organic matter content did not change during release but decreased during oxidation. The proportion of humic acid decreased, while the proportion of fulvic acid increased. The total removal efficiency of 21 antibiotics from AD biosolids was 82.2 %, and the released heavy metals did not cause secondary pollution. The cost of the method developed in this study was $2.5/t (with 10 % solid content). Thus, this method is highly efficient, low cost, and enhances the safety and utilization of farmland AD biosolids.