Arsenic removal from groundwater using iron electrocoagulation: Effect of charge dosage rate

Abstract

We demonstrate that electrocoagulation (EC) using iron electrodes can reduce arsenic below 10 μg/L in synthetic Bangladesh groundwater and in real groundwater from Bangladesh and Cambodia, while investigating the effect of operating parameters that are often overlooked, such as charge dosage rate. We measure arsenic removal performance over a larger range of current density than in any other single previous EC study (5000-fold: 0.02 – 100 mA/cm²) and over a wide range of charge dosage rates (0.060 – 18 Coulombs/L/min). We find that charge dosage rate has significant effects on both removal capacity (μg-As removed/Coulomb) and treatment time and is the appropriate parameter to maintain performance when scaling to different active areas and volumes. We estimate the operating costs of EC treatment in Bangladesh groundwater to be $0.22/m³. Waste sludge (∼ 80 – 120 mg/L), when tested with the Toxic Characteristic Leachate Protocol (TCLP), is characterized as non-hazardous. Although our focus is on developing a practical device, our results suggest that As[III] is mostly oxidized via a chemical pathway and does not rely on processes occurring at the anode.

Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Environmental Science and Health, Part A, to view the free supplemental file.

Keywords:

• Electrocoagulation
• arsenic
• water treatment
• Bangladesh
• India
• Cambodia
• dosage rate

Acknowledgments

We gratefully acknowledge support for this work by The Richard C. Blum Center for Developing Economies, the USEPA P3 (People, Prosperity, and Planet) Phase I award, the UC Berkeley Bears Breaking Boundaries Contest and LDRD funds from Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231. We are also thankful to Iqbal and Kamal Quadir and the non-profit organization RDI-Cambodia for supporting field trials, along with the students who have supported this work, including Case van Genuchten, Lei Li, Rebecca Lin, Andy Torkelson, Shreya Ramesh, Carol Soares, Michele Muller, John Wang, Debbie Cheng, Marianna Kowalczyk, Kate Ming, Scott McLaughlin, Yola Bayram, and Johanna Mathieu. Thanks also to LBNL researchers Jonathan Slack and Howdy Goudey for generous assistance and guidance in the design and fabrication of various reactors.