Publication Details

Emamjomeh, M. & Sivakumar, M. (2005). Defluroridation using a continuous electrocoagulation (EC) reactor. New Zealand Water & Wastes Association Conference (pp. 1-19). New Zealand: New Zealand Water & Wastes Association.


Electrocoagulation (EC) is a process of passing a steady electric current through liquid using aluminium or iron electrodes to remove impurities in water. When aluminium electrodes are used, the aluminium goes into solution at the anode and hydrogen gas is released at the cathode and dissolution of A1 anodes produces aqueous aluminium species. Experiments were undertaken to investigate the effects of the different parameters such as: current density (12.5-50 A/m2), flow rate (150-400 mL/min), initial pH (4-8), and initial fluoride concentration (5-15 mg/L) on the fluoride removal efficiency in a continuous flow electrocoagulator. The experimental results showed that for an initial fluoride concentration of 10 mg/L when flow rates varied from 150 to 300 mL/min, the residual fluoride concentration reached to less than 1 mg/L when the current densities were respectively increased from 18.75 A/m2 to 50A/m2. It appears that for higher defluoridation efficiency, the current density needs to be increased when flow rate is increased. The composition of the sludge produced was analysed using X-ray diffraction (XRD) spectrum. The strong presence of the hydroxyl-aluminium in the final pH range between 6 and 8, which maximizes the formation of fluoro-hydroxide aluminium complex, is the main reason for defluoridation by electrocoagulation. The results obtained showed that the continuous flow electrocoagulation technology is an effective process for defluoridation of potable water supplies and could also be utilized to the defluoridation of industrial wastewater.

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New Zealand Water and Wastes Association

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