Removal of Antibiotic Resistance From Municipal Secondary Effluents by Ozone-Activated Carbon Filtration

Abstract

At wastewater treatment plants (WWTPs), additional steps are introduced for removal of organic micropollutants (OMPs) from the treated effluents, especially pharmaceutical residues. At the same time, a new concern is emerging: antibiotic resistance (AR). This research studied the effect of ozonation, coagulation and granular activated carbon (GAC) filtration applied as tertiary treatment for the removal of OMPs and nutrients, on AR removal. Bacterial culture methods in selective media were used to screen for four different microorganisms: two faecal indicators (Escherichia coli and Enterococci) as antibiotic sensitive bacteria (ASB), and a resistant strain of each of these bacteria, namely Extended-Spectrum Beta-lactamase producing E. coli (ESBL-E.coli) and Vancomycin Resistant Enterococci (VRE) as antibiotic resistant bacteria (ARB). At laboratory scale, ozonation experiments (ozone dose 0.4–0.6 g O3/g DOC) and coagulation experiments using Polyaluminum chloride (PAX-214) and FeCl3 (coagulant dose 0.004–1 mM/L) were performed using secondary effluent from two municipal WWTPs. In addition in a pilot plant and full-scale plant ozonation (ozone dose 0.4 g O3/g DOC) and GAC filtration (empty bed contact time 15 min) were studied for AR removal. No significant differences were found between ARB and ASB removal for coagulation and ozonation which could indicate that ASB can be used as an initial proxy for ARB removal for these technologies. In the laboratory experiments, ozonation and coagulation showed a good removal of both ARB and ASB. However, the doses needed to reach 2–3 log removal were a factor 2.5–4 (ozonation) and 250 (coagulation) higher than applied for OMP removal (by ozonation) and phosphorus (P) removal (by coagulation). In the GAC filters, the risk of ARB enhancement occurred, especially in filters with a matured biology. Although these bacteria are not necessarily directly harmful, they can pass down their resistance to pathogenic bacteria via horizontal gene transfer.

The Fate and Occurrence of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes during Advanced Wastewater Treatment and Disinfection: A Review

“…In addition, Alexander et al [110] observed the increase of vanA and bla VIM in abundance with surviving bacteria by 4-and 7-fold after ozonation treatment in a pilot scale ozone system. Increasing the ozone dose enhances the ARB removal efficiency [69,70,107]. However, Zheng et al [85] observed that increasing the ozone dose did not contribute to a significantly higher ARGs removal efficiency.…”

“…Activated carbon is often used for the adsorption of various pollutants from wastewater such as organic compounds, heavy metals, and pharmaceutical products [67,68]. Activated carbon can be used for the adsorption of antibiotics, ARGs, and ARB found in wastewater [69]. However, ARB and ARGs removal has not yet been widely studied.…”

“…Slipko et al [70] used a granular activated carbon filter downstream of a pilot-scale ozonation system and observed that sulI and tetW genes were reduced by up to 1 log while the relative abundance of bla TEM increased significantly. Spit et al [69] observed in a pilot-scale ozonation and GAC filtration system that vancomycinresistant enterococci (VRE) increased by 0.5 log after GAC filtration, demonstrating that activated carbon increases antibiotic resistance. Moreover, they contributed the augment of VRE to acquiring of ARGs released by cell lysis of bacteria caused by ozonation.…”

Ozonation of Non-Woven Ultrathin Fibrous Biomaterials for Medical and Packaging Implementations

“…Ozone can play a role in medicine [34,35] as well as in other areas due to its antibacterial properties and the continued spread of the phenomenon of antibiotic resistance [36][37][38], that is, the inability of antibiotics to effectively fight infections and bacteria, a phenomenon defined by the excessive and often inappropriate use of antibiotics as for people as well as for animals.…”