Removal of pharmaceuticals in WWTP effluents by ozone and hydrogen peroxide

Abstract

Ozonation to achieve removal of pharmaceuticals from wastewater effluents, with pH values in the upper and lower regions of the typical range for Swedish wastewater, was investigated. The main aim was to study the effects of varying pH values (6.0 and 8.0), and if small additions of H 2O2 prior to ozone treatment could improve the removal and lower the reaction time. The effluents studied differed in their chemical characteristics, particularly in terms of alkalinity (65.3–427 mg∙ℓ −1 HCO3-), COD (18.2–41.8 mg∙ℓ−1), DOC (6.9–12.5 mg∙ℓ−1), ammonium content (0.02–3.6 mg∙ℓ −1) and specific UV absorbance (1.78–2.76 ℓ∙mg−1∙m−1). As expected, lower ozone decomposition rates were observed in the effluents at pH 6.0 compared to pH 8.0. When pH 8.0 effluents were ozonated, a higher degree of pharmaceutical removal occurred in the effluent with low specific UV absorbance. For pH 6.0 effluents, the removal of pharmaceuticals was most efficient in the effluent with the lowest organic content.

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