Civil Engineering Department, NIT Sikkim, Ravangla, Sikkim, India.
Civil Engineering Department, IIEST, Shibpur, Howrah, West Bengal, India.
Arch Environ Contam Toxicol. 2021 Jan;80(1):248-258. doi: 10.1007/s00244-020-00799-8. Epub 2021 Jan 4.
Arsenic contamination in drinking water is a great concern in different regions of the world as well as in India. Several technologies have been investigated to remove arsenic from water, such as coagulation and co-precipitation, ion exchange, adsorption, and reverse osmosis. In the present research, electrocoagulation with iron electrodes has been assessed as a treatment technology for arsenic removal from groundwater to reach concentrations below 0.01 mg/L (WHO limit) and which is technically effective, affordable for the local area, and easy to operate and maintain. Electrochemically generated iron is converted to hydrated ferric oxide within the contaminated water, which takes up the arsenic from water. A downstream filtration unit (sand or activated alumina) is applied to remove ferric hydroxide flocs produced during the process. The laboratory experiments were conducted in a batch reactor using iron plates as electrodes with monopolar configuration to study the effects of initial pH and electro-charge loading (ECL) on arsenic removal. The optimum operating condition was observed for an electro-charge loading of 25-30 Coulombs/L at pH 7.0 and an initial arsenic concentration of 0.2 mg/L. Two field trials were implemented in West Bengal after suitably designing the electrocoagulation system. Arsenic removal was significant (75-80%) delivering safe water with arsenic below 0.01 mg/L (acceptable limit). Passivation of the electrodes occurred during the operation and calcium-based (including iron) deposition was observed on the cathodes. Passivation is avoidable after running regular polarity reversal of the electrodes.
饮用水中的砷污染是世界上不同地区以及印度关注的一个重大问题。已经研究了几种技术来去除水中的砷，例如混凝和共沉淀、离子交换、吸附和反渗透。在本研究中，评估了铁电极的电化学混凝作为一种从地下水去除砷的处理技术，以达到低于 0.01mg/L（世卫组织限值）的浓度，并且该技术在技术上有效、适合当地情况、易于操作和维护。电化学生成的铁在受污染的水中转化为水合氧化铁，从水中吸收砷。在下流的过滤单元（砂或活性氧化铝）中应用以去除过程中产生的氢氧化铁絮体。实验室实验在使用铁板作为电极的批处理反应器中进行，采用单极配置来研究初始 pH 值和电荷负载 (ECL) 对砷去除的影响。在 pH 值为 7.0 和初始砷浓度为 0.2mg/L 的情况下，观察到最佳操作条件为 25-30 库仑/升的电荷负载。在恰当地设计了电化学混凝系统之后，在西孟加拉邦进行了两次现场试验。砷去除效果显著（75-80%），提供了低于 0.01mg/L（可接受限值）的安全饮用水。在运行过程中会发生电极钝化，并且在阴极上观察到基于钙（包括铁）的沉积。定期反转电极极性后可以避免电极钝化。
