Removal of nickel from metal plating wastewater with iron scrap column

Abstract

This research investigated removal of nickel from metal plating wastewater with iron scrap column. Batch experiments and continuous flow experiments were conducted. The batch experiments were performed to determine the effect of pH on the nickel removal efficiency. The continuous flow experiments were used to study the effect of column height, influent flow rate, and nickel concentration on column performance. Batch experimental results indicate that pH was an important factor affecting nickel removal. The maximum nickel adsorption by iron oxide occurred in the pH range of 6 to 7 and the hydroxyl group was the dominant adsorbable species. The continuous flow experiment was conducted with a two-month operation period. Three columns were placed in series and three column heights, 30 cm, 40, and 50 cm were tested. Only 12% the data obtained from the tests with column height 30-cm could reach a nickel concentration of less than 1 mg/L in effluent. Whereas the percentage removal achieved at the same level with column height of 40 cm and 50 cm were 38% and 29%, respectively. The optimum column height was 40 cm. Longer column height would increase nickel sorption, however, it also resulted in insufficient oxygen to oxidize iron, which affected HFO sorption capacity. Three flow rates, 5 L/d, 10 L/d, and 15 L/d, were tested and nickel removal efficiencies were 86.27%, 84.92%, and 75.80%, respectively. Larger flow rate decreases removal efficiency. During the study of the effect of nickel concentration on column performance, the maximum nickel sorption for influent nickel concentrations at 10, 20, 50, and 100 mg/L were 10.07, 9.04, 14.83, and 20.15 mg-Ni/gram iron, respectively.