Long-term application of ozonation for removal of pharmaceuticals from wastewater treatment plant effluent: Effectiveness, control strategies, ecotoxicity

Summary

This study presents the results of a seven-month testing of a pilot-scale ozonation system as a quaternary treatment of effluent from the WWTP in Blansko city (Czechia) with a focus on real-time control of ozonation technology based on the measurement of UV absorbance at wavelength 254 nm (UV254). The study investigated the effect of ozonation on 38 pharmaceuticals (PHAs) that were commonly found in Blansko WWTP effluent. Moreover, the method of ensuring a stable reduction of selected watchlist of PHAs in fluctuating conditions was investigated by evaluating UV254. During testing, an ozone dose of 0.8 mg O3/mg TOC was sufficient to reach 80 % overall removal of all investigated PHAs on average. It is necessary to mention that this sufficient dose only applies to the investigated set of pharmaceutical substances and might differ significantly for other sets of pharmaceuticals or different locations. The use of UV254 absorbance and its relative decrease during ozonation correlated to a stable and reasonably accurate monitoring of the actual level of PHAs removal of investigated/targeted PHAs. Estimating actual levels of reduction of evaluated substances in routine operation will significantly simplify operation, reduce the costs of analytical analyses and ensure compliance with required limits.