2.3.3. Experiments with NF concentrate from real secondary effluent
Total 8 L of NF concentrate was obtained from nearly 32 L real secondary effluent. Each 4 L concentrate was used for ozonation or UV/O3 experiment without any antibiotics spiked. Both experiments proceeded for 30 min. At regular time intervals, 20 mL samples were withdrawn from the reactor. Samples were taken and shaken in centrifuge tubes, then placed at room temperature for 2 h to remove residual ozone, which was according to the method reported in previous study [25]. Sodium nitrite was not added as it could interfere the measurement of UV254 absorbance or UV absorption spectra.