The Effect of Fe(0)–Al(0) Co-corrosion on the Bacterial Decontamination Property of Fe(0)

Zero-valent iron is known for its ability to immobilize bacterial contaminant in water. In this study, the effect of enhancing the rate of corrosion of zero-valent iron by co-corrosion with zero-valent aluminium on bacteria immobilization properties of zero-valent iron is investigated. 250 mL portions of decanted wastewater from primary facultative pond spiked with 5 mL of 1000 mg/L fluoride solution were equilibrated, in triplicate with 3 g of pure zero-valent aluminium, iron and 3 g of their equal-mass mixtures for a period of 24 h. Bacteria count and fluoride level in the treated wastewater were determined by pour plate and ion selective electrode methods, respectively, at the interval of six hours throughout the period of 24 h and average values were calculated and used to plot graphs. Findings indicate that a dose of 3 g/250 mL of pure zero-valent aluminium, iron and 3 g of their equal-mass mixture lowered the bacteria colony forming unit (CFU) by 60, 79 and 100%, respectively, in a period of 24 h. The amount of corrosion product was found to increase from 0 g when pure aluminium was used to 0.31 and 1.56 g when pure zero-valent iron and their equal-mass mixtures were used. Increasing material dose from 0.1 to 3 g increased the bacteria removal efficiency from 28 to 100% respectively. Increase in contact time was found to lower the CFU from 59 to 9, 2, 0 and 0 when contact time was varied from 0 to 6, 12, 18 and 24 h. Findings indicate that combining zero-valent aluminium with iron has a synergistic effect on both bacteria and fluoride removal from water. The increased bacterial removal efficiency when the two materials were used together could be attributed to the increased formation of the corrosion products observed when the two materials were mixed, hence, increased co-precipitation. Observed increase in bacteria removal efficiency when material dose was increased is attributable to the increase in formation of precipitation agents such as Fe3+ and Al3+ which increase with increasing material dose. These findings could imply that a water treatment system involving co-corrosion of zero-valent aluminium with iron could be investigated further as a comprehensive method for removal of both fluoride and bacteria from contaminated wastewater.