TiO2 nanotube arrays photocatalytic ozonation for the removal of antibiotic ciprofloxacin from the effluent of a domestic wastewater treatment plant: Towards the process upscaling

The global use of antibiotics and exposure to the water environment through domestic wastewater treatment plants has increased substantially in the last decade. Traditional wastewater treatment technologies are not capable of removing antibiotics from wastewater; therefore, advanced oxidation processes (AOPs) have gained attention as one of the possible alternatives. This study aimed to develop and test a titanium dioxide nanotube arrays (TiO2 NTAs) photocatalytic ozonation process, to treat secondary effluent. Six AOPs were examined, including photolysis, photocatalysis, and photocatalytic ozonation. The photocatalytic ozonation process using TiO2 NTAs was found to be the most effective, with the highest antibiotic ciprofloxacin removal rate constants of 1.1 min−1 and 0.64 min−1 in model wastewater and secondary effluent, respectively. Furthermore, the wastewater treatment time decreased 5 times when ozone was introduced into the TiO2 NTAs reactor, showing a positive effect of synergy. Additionally, photocatalytic ozonation resulted in superior disinfection performance, achieving Log-5 bacterial reduction after 10 min, and removal of 44–57 % of total organic carbon (TOC) after 30 min of treatment. The results indicate that the TiO2 NTAs photocatalytic ozonation process can be successfully applied to treat biologically stabilized wastewater streams for the removal of antibiotics, bacterial contamination, and persistent organic matter simultaneously.