Erythromycin Abatement from Water by Electro-Fenton and Peroxyelectrocoagulation Treatments

Abstract

Electro-Fenton (EF) and peroxyelectrocoagulation (PEC) processes were investigated to mineralize 10 mg L−1 erythromycin from ultrapure water, evaluating the influence of the anode material (BDD and Fe), current density (janode) (5 mA cm−2 and 10 mA cm−2), oxygen flowrate injected to the cathode (0.8 L min−1 O2 and 2.0 L min−1 O2) and pH (2.8, 5.0 and 7.0) on the process efficiency and the electricity costs. 70% mineralization was reached after applying 0.32 A h L−1 under the best operational conditions: PEC treatment at 5 mA cm−2, 2.0 L min−1 O2 and pH 2.8. The electricity consumption of the electrochemical cell under these conditions was approximately 0.3 kWh m−3. Early-stage intermediates produced from erythromycin degradation were identified and quantified throughout the treatment and a potential erythromycin degradation pathway was proposed. The most appropriate operational conditions tested with synthetic solutions were applied to treat a real effluent from the tertiary treatment of an urban wastewater treatment plant. All emerging compounds listed in the EU Decision 2018/840 (Watch List 2018) were determined before and after the PEC treatment. All listed pollutants were degraded below their quantification limit, except estrone and 17-α-ethinylestradiol which were 99% removed from water. Electricity consumption of the electrochemical cell was 0.4 kWh m−3. Whilst awaiting future results that demonstrate the innocuity of the generated byproducts, the results of this investigation (high removal yields for emerging pollutants together with the low electricity consumption of the cell) indicate the promising high potential of PEC treatment as a water treatment/remediation/regeneration technology.