The effect of ultrafiltration process on the fate of antibiotic-related microcontaminants, pathogenic microbes, and toxicity in urban wastewater

Ultrafiltration (UF) was assessed at chemical, microbiological, genetical and toxicological level and in terms of removing specific antibiotic-related microcontaminants from urban wastewater. The UF capacity to remove various antibiotics (clarithromycin, erythromycin, ampicillin, ofloxacin, sulfamethoxazole, trimethoprim, and tetracycline; [A(0)] = 100 mu g L-1) was optimised with respect to the feed recirculation rate (25-50%) and feed/transmembrane pressure (1.5-3/1.5-2.4 bar, respectively). Here, we tested the UF capacity to reduce the cultivable bacteria (faecal coliforms, total heterotrophs, Enterococci, Pseudomonas aeruginosa), enteric opportunistic pathogens, including antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) load. Moreover, the toxicity towards Daphnia magna and three plant species was investigated. Upon optimisation of UF, the removal of antibiotics ranged from 19% for trimethoprim to 95% for clarithromycin. The concentration of cultivable faecal coliforms in the permeate was significantly reduced compared to the feed (P < 0.001), whereas all the bacterial species decreased by more than 3 logs. A similar pattern of reduction was observed for the ARGs (P < 0.001) and enteric opportunistic pathogens (similar to 3-4 logs reduction). A nearly complete removal of the antibiotics was obtained by UF followed by granular activated carbon adsorption (contact time: 90 min), demonstrating the positive contribution of such combination to the abatement of chemical micmcontaminants.

Automated summary

This study assessed the effectiveness of ultrafiltration (UF) in removing antibiotic-related microcontaminants from urban wastewater. The results showed that UF combined with granular activated carbon adsorption can effectively remove antibiotics. Furthermore, UF was also able to reduce the load of cultivable bacteria, antibiotic-resistant bacteria, and antibiotic-resistance genes, as well as exhibit toxicity inhibition towards aquatic organisms and plants.