Studies on adsorption of nickel on sand from constructed wetland and effect of leaching agents.

The present study chronicles experiments done on the feasibility of exploiting sand's natural capacity as an adsorbant for the removal of nickel laden wastewater. Batch adsorbtion studies were carried out. Leaching agents such as 0.01 M EDTA (disodium salt), 0.1 N HCI and acetic acid alongwith water as control showed 0.01 M EDTA-Na and 0.1 N HCl as suitable leaching agents to enhance metal removal from sand. Pot experiments were successively carried out with Arundo donax plants to determine the effectiveness of treatment on the sand. It was found that sand could continue as a good substrate for plant growth and the amount of leaching agent required for a pilot scale constructed wetland was estimated. The maximum amount of nickel adsorbed was 5 mg/L at a pH of 6. EDTA was selected as the chelating agent and the pot experiments showed no immediate effects on plant growth.