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The nonbiodegradable pollutants and high-strength nitrogen- and sulfur-containing compounds found in the wastewater from the thin-film transistor liquid-crystal display (TFT-LCD) screen industry are difficult to degrade. An electro-Fenton procedure has been developed to increase the efficiency of the ferric reduction. The organic compounds are ionized or oxidized by direct electrolysis on the anode in the electrolytic cell of the electro-Fenton process. The effects of operating parameters such as concentrations of Fe2+ and H2O2, pH, and current density on chemical oxygen demand (COD) removal were determined. The degradation of the TFT-LCD wastewater was faster by the electro-Fenton process than the conventional Fenton process. The highest COD removal efficiency was 100% at 120 min; pH = 4; [Fe2+] = 3.5 mM; [H2O2] = 285 mM; and 1.5 A/dm2 of current density. The energy cost of the electro-Fenton process for treating TFT-LCD wastewater was approximately US$0.1/L. [ABSTRACT FROM AUTHOR]

The TFT-LCD screen (thin film transistor liquid crystal display) industry has been growing rapidly in Taiwan in recent years. The wastewater from this industry contains many non-biodegradable pollutants and high strength nitrogen and sulfur containing compounds which are difficult to degrade. Fenton and electro-Fenton with double-cathode processes were used to treat the high COD content of real TFT-LCD wastewater which cannot be removed by conventional processes. The effect of operating parameters such as pH, Fe2+, H2O2 concentration and electrical current on COD removal were determined. The electro-Fenton process rapidly degraded the TFT-LCD wastewater in the first 20 minutes while in the Fenton process, the rapid degradation occurred in the first 60 min. This showed that electro-Fenton process could degrade the TFT-LCD wastewater faster than the Fenton process. The highest COD removal efficiency was found to be 100% at 120 min at pH = 4, [Fe2+] = 3.5 mM, [H2O2] = 285 mM and 1.5 A of electrical current of electro-Fenton process. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 368-373, 2016 [ABSTRACT FROM AUTHOR]