Waste-derived iron catalyzed bio-electro-Fenton process for the cathodic degradation of surfactants

The application of waste-derived iron for reuse in wastewater treatment is an effective way of utilizing waste and attaining sustainability in the overall process. In the present investigation, bio-electro-Fenton process was initiated for the cathodic degradation of surfactants using waste-iron catalyzed MFC (WFe-MFC). The waste-iron was derived from spent tonner ink using calcination at 600 °C. Three surfactants namely, sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide, and Triton x-100 were selected as target pollutants. The effect of experimental factors like application of catalyst, contact time, external resistance, and anodic substrate concentration on the SDS degradation was investigated. At a neutral pH, the cathodic surfactants removal efficiency in WFe-MFC was above 85% in a contact time of 180 min with the initial surfactant concentration of ∼20 mg L^-1 and external resistance of 100 Ω. The long-term operation using secondary treated real wastewater with unchanged cathode proved that the catalyst was still active to produce effluent SDS concentration of less than 1 mg L^-1 in 4 h of contact time after 16 cycles. In a way, the present investigation suggests a potential application for spent tonner ink in the form of Fenton catalyst for wastewater treatment via bio-electro-Fenton MFC.