Combined Effects of Electro-Coagulation and Electro-Oxidation on Pesticide Wastewater, Using Iron Electrodes and Studying Current Variation and Electrode Gap

Abstract

This study explores the combined use of Electrocoagulation (EC) and Electro oxidation (EO) to removal of persistent organic compounds from industrial wastewater, focusing on pesticide wastewater. The EC process efficiently removes colloidal and suspended particles within 45-60 minutes, achieving significant reductions in Chemical Oxygen Demand (COD), although some stable organic compounds remain. The EO process further breaks down these organic pollutants, reducing COD, Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), pH, and iron concentrations, but requires more time, especially for colloidal particles. The hybrid EC-EO method first utilizes EC to eliminate charged species and then applies EO to degrade the remaining organic compounds, leading to the effective reduction of various pollutants within approximately one hour. The results indicate that iron electrodes were particularly effective in removing pollutants under different treatment conditions. The combined EC-EO treatment method demonstrates significant potential for the efficient treatment and separation of contaminants in industrial wastewater, offering a promising solution for improving water quality and reducing environmental pollution.

Introduction

Freshwater scarcity is a critical global issue, with over 2.1 billion people lacking safe water daily, causing millions of deaths annually. Industrial wastewater contains complex pollutants, including bio-refractory organic compounds that are difficult to treat using conventional biological methods, necessitating advanced treatments.

Electrocoagulation (EC) and Electrooxidation (EO) are electrochemical methods used to treat industrial wastewater. EC uses metal electrodes (typically iron or aluminum) to generate coagulants that remove contaminants via flocculation and flotation, offering advantages like high efficiency, low cost, less sludge, and no need for added chemicals. EO breaks down pollutants through direct or indirect oxidation processes, producing strong oxidants on-site that degrade organic contaminants. Advanced electrode materials, such as boron-doped diamond, improve EO efficiency and stability.

The study involved treating industrial wastewater from an Indian industrial zone using EC and EO. Experiments varied current density and electrode gaps to optimize pollutant removal, measuring parameters like COD, BOD, TOC, color, turbidity, and dissolved solids. Results showed that increasing current and electrode gap improved treatment efficiency, significantly reducing COD from 4200 mg/L to levels meeting discharge standards. Combining EC and EO treatments enhanced pollutant removal effectiveness.

Overall, the research demonstrates that integrated electrochemical treatments (EC followed by EO) can effectively remove organic pollutants and improve wastewater quality beyond what conventional biological treatment achieves, making it suitable for complex industrial effluents.

Conclusion

The Electrocoagulation (EC) and Electro oxidation (EO) technique proves to be highly effective in treating and separating contaminants present in industrial wastewater. This technology demonstrates significant potential for treatment, with electrochemically generated iron concentrations varying from 2.12 to 1.21 mg/l. The following conclusions can drawn from the findings. Iron electrodes exhibited superior performance in pollutant removal from pesticide wastewater at a current of 3 Amperes. After 60 minutes of treatment, with pH adjustments and a consistent electrode gap of 1 mm, the removal efficiencies were as follows: BOD (89.7%), COD (89.96%), TOC (90.03%), Electrical Conductivity (71.41%), pH (86.29%), and Iron concentration increased by 17.64%. Conversely, when utilizing an electrode gap of 5 mm and maintaining a constant current of approximately 5 Amperes for 60 minutes, the removal efficiencies improved further: BOD (93.77%), COD (97.85%), TOC (51.56%), Electrical Conductivity (55.07%), pH (83.70%), and Iron concentration reduced by 45.88%.

References

[1] Karimirahnama, A., Mozaffarian, M., Dabir, B., & Amrabadi, N. E. (2025). Assessment of simultaneous removal of salt and dye by utilizing capacitive deionization and UV-electro oxidation hybrid process in saline wastewater treatment. Desalination, 594, 118254. [2] Linares-Hernández, I., Barrera-Díaz, C., Bilyeu, B., Juárez-GarcíaRojas, P., & Campos-Medina, E. (2010). A combined EC–EO treatment for industrial wastewater. Journal of hazardous materials, 175(1-3), 688-694. [3] García-García, A., Martínez-Miranda, V., Martínez-Cienfuegos, I. G., Almazán-Sánchez, P. T., Castañeda-Juárez, M., & Linares-Hernández, I. (2015). Industrial wastewater treatment by EC–EO processes powered by solar cells. Fuel, 149, 46-54. [4] Rajkumar, D., & Palanivelu, K. (2004). Electrochemical treatment of industrial wastewater. Journal of hazardous materials, 113(1-3), 123-129. [5] Kruthika, N. L., Karthika, S., Raju, G. B., & Prabhakar, S. (2013). Efficacy of EC and EO for the purification of wastewater generated from gelatin production plant. Journal of Environmental Chemical Engineering, 1(3), 183-188. [6] Mitsudo, K., Kumagai, H., Takabatake, F., Kubota, J., & Tanaka, H. (2007). Anionic WS-TEMPO-mediatory EO of alcohols in water: halide-free oxidation directed towards a totally closed system. Tetrahedron Letters, 48(51), 8994-8997. [7] Piya-Areetham, P., Shenchunthichai, K., & Hunsom, M. (2006). Application of EO process for treating concentrated wastewater from distillery industry with a voluminous electrode. Water Research, 40(15), 2857-2864. [8] Masid, S., Waghmare, S., Gedam, N., Misra, R., Dhodapkar, R., Nandy, T., & Rao, N. N. (2010). Impact of EO on combined physicochemical and membrane treatment processes: Treatment of high strength chemical industry wastewater. Desalination, 259(1-3), 192-196. [9] Kapa?ka, A., Fóti, G., & Comninellis, C. (2007). Investigations of electrochemical oxygen transfer reaction on boron-doped diamond electrodes. Electrochimica Acta, 53(4), 1954-1961. [10] Canizares, P., Arcís, M., Sáez, C., & Rodrigo, M. A. (2007). Electrochemical synthesis of ferrate using boron doped diamond anodes. Electrochemistry communications, 9(9), 2286-2290. [11] Bazrafshan, E., Mohammadi, L., Ansari-Moghaddam, A., & Mahvi, A. H. (2015). Heavy metals removal from aqueous environments by EC process–a systematic review. Journal of environmental health science and engineering, 13, 1-16. [12] Mollah, M. Y. A., Schennach, R., Parga, J. R., & Cocke, D. L. (2001). EC —science and applications. Journal of hazardous materials, 84(1), 29-41. [13] Rice, E. W., Bridgewater, L., & American Public Health Association (Eds.). (2012). Standard methods for the examination of water and wastewater (Vol. 10). Washington, DC: American public health association. [14] Raju, G. B., Karuppiah, M. T., Latha, S. S., Parvathy, S., & Prabhakar, S. (2008). Treatment of wastewater from synthetic textile industry by EC–EO. Chemical Engineering Journal, 144(1), 51-58. [15] Álvarez, J. M., Zuccalli, M. B. A., Arturi, T., & Bianchi, G. L. (2023). Combined EC and EO treatment system for real effluents from the fishing industry. Heliyon, 9(4).

Copyright

Copyright © 2025 Satyam Singh, Ayush Chaubey, Alok Kumar, Abhishek Kumar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.