Pharmaceuticals, toxicity and natural fluorescence intensity of biologically treated hospital wastewater removed by pilot and laboratory scale ozonation

We studied a bubble reactor based pilot ozonation system for removal of pharmaceuticals and toxicity from biologically treated hospital wastewater. To remove degradation products generated by ozonation, polishing with suspended biofilm carriers investigated. Removal of pharmaceuticals was comparable between the pilot treatment using a bubble column and offline laboratory experiments applying batch ozone addition. The removal rate constants of pharmaceuticals were normalized to dissolved organic carbon (DOC) and thus the efficiencies were comparable to literatures. Natural fluorescence intensity was used as an easily measurable parameter for the oxidation of organic matter in the wastewater. The remaining fluorescence after ozonation decayed slowly with holding time, but was removed fast by biofilm carriers simulating a possible polishing of ozonated effluent in a downstream biofilter. The toxicity of the hospital wastewater as measured with Microtox® and was found to reduce from 80 % to 50 % inhibition with the biological treatment. Ozonation reduced the inhibition further to 20%.