Nitrate removal from water using zero-valent aluminium

Nitrate pollution in surface and groundwater is known to adversely affect human health, water quality and the health of aquatic ecosystems. Zero-valent aluminium is a strong reductant for ions such as nitrate. In this study, its use in nitrate reduction efficiency was evaluated as a function of pH, aluminium dosage and aluminium particle size through a lab-scale investigation. The most effective pH for complete nitrate removal, with an initial concentration of 14.0 +/- 1.0 mg N/L, was found to be 13 +/- 0.2. Under this condition, complete removal was achieved in 5 min, using aluminium particle size of 1-3 mu m and aluminium-to-nitrate (NO3--N) ratio of 125. The 1-3 mu m and 297-841 mu m aluminium particles removed nitrate at a reaction rate constant (k) of 0.048 +/- 0.017 (mg-N/L)(1.53)/min and at 0.042 +/- 0.014 (mg-N/L)(1.28)/min, respectively. The use of smaller aluminium particles was found to be more effective for nitrate removal than large particles, and it was observed that for these particle sizes, aluminium dosages was less of a factor than any other experimental conditions evaluated.