Removal of pharmaceuticals, toxicity and natural fluorescence by ozonation in biologically pre-treated municipalwastewater, in comparison to subsequent polishing biofilm reactors

Ozonation followed by a polishing moving bed biofilm reactor (MBBR) was implemented in pilot and laboratory to remove the residual pharmaceuticals and toxicity from wastewater effluent, which was from a pilot hybrid system of MBBR and activated sludge, receiving municipal wastewater. The delivered ozone dosages achieving 90% pharmaceutical removal were determined both in pilot and laboratory experiments and they were normalised to dissolved organic carbon (DOC), illustrating our findings were comparable with previously published literature. During wastewater ozonation, the intensity of natural fluorescence was found to be greatly associated with the concentrations of the studied pharmaceuticals. In pilot experiments, toxicity, measured by Vibrio fischeri, increased after ozonation at delivered ozone dosages at 0.38-0.47 mg O₃/mg DOC and was completely removed by the subsequent polishing MBBR. Laboratory experiments verified that the polishing MBBR was able to remove the toxicity produced by the ozonation.