This study assesses the degradation by electrochemical oxidation via boron doped diamond (BDD) electrodes of the selected pharmaceutical compounds iopromide (IOP), sulfamethoxazole (SMX), 17alpha-ethinylestradiol (EE2) and diclofenac (DCF) in simulated wastewater and real hospital effluent wastewater. The influence of the flow rate in the electrochemical cell, applied current, initial compound concentration and wastewater matrix (simulated (SWW) versus real effluent (RWW) wastewater) was evaluated. A kinetic evaluation confirmed that the degradation can be described via pseudo first-order reaction kinetics for all experimental conditions tested. It was shown that SMX, EE2 and DCF degraded readily in SWW and RWW. The degradation of IOP was significantly slower, which is in agreement with previously reported slow degradation kinetics using typical advanced oxidation processes. Activation energies for the degradation reactions were calculated. The flow rate in the electrochemical cell had only a moderate effect on the degradation rate of EE2 and DCF. The applied current, however, had a major effect. The BDD electrochemical oxidation was shown to be an effective technique for removing pharmaceutical components from the effluent of a biological hospital wastewater treatment plant. However, the slower degradation of transformation products should be taken into account, when a full mineralization of the pharmaceuticals is pursued.

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In this paper, the abatement of adsorbable halogenated organic compounds (AOX) from an industrial wastewater containing relatively high chloride concentrations by a combined chemical and biological oxidation is assessed. For chemical oxidation, the O3/UV, H2O2/UV and photo-Fenton processes are evaluated on pilot scale. Biological oxidation is simulated in a 4 h respirometry experiment with periodic aeration. The results show that a selective degradation of AOX with respect to the matrix compounds (expressed as chemical oxygen demand) could be achieved. For O3/UV, lowering the ratio of O3 dosage to UV intensity leads to a better selectivity for AOX. During O3-based experiments, the AOX removal is generally less than during the H2O2-based experiments. However, after biological oxidation, the AOX levels are comparable. For H2O2/UV, optimal operating parameters for UV and H2O2 dosage are next determined in a second run with another wastewater sample.

Abstract:In this study, the degradation of 4-chlorophenol (4-CP) is investigated by using a combination of microwave (MW) irradiation and hydrogen peroxide as oxidant (the MW-H 2 O 2 -process). The influence of the critical parameters on the efficiency of the process is examined by applying Partial Least Square Regression (PLS) on a Design of Experiments (DOE). Also, a kinetic evaluation of the process is carried out. Results showed that the MW-H 2 O 2 -process is effective in the degradation of 4-CP. The most influential parameter of the MW-H 2 O 2 -process is the reaction temperature. Besides this parameter, the reaction time, initial 4-CP concentration, and initial hydrogen peroxide concentration have a (minor) influence on the 4-CP degradation. A maximum degradation efficiency within the levels of the DOE (remaining percentage of 4-CP of 34%) was achieved with an initial 4-CP concentration of 1000 mg/L, an initial H 2 O 2 concentration of 11 g/L, reaction temperature of 180 • C, and reaction time of 20 min. The process follows pseudo first order reaction kinetics.