INVESTIGATION OF METAL REMOVAL USING NATURAL LIMESTONE ROCK

The objective of this study is to determine the removal of metals through the application of natural limestone rock in pilot column experiments. Elevated concentrations of metals have been measured in sites affected by anthropogenic activities such as industrial effluents and abandoned mine waste drainages. The pilot experiments for this study were conducted utilizing limestone rocks from the Madera Formation in New Mexico which were crushed and packed (150 grams) in three foot long Plexiglas columns. Both bulk and particle densities were measured from which the total pore volume was calculated as 35 mL. Synthetic water was spiked with metals (As, Cd, Cr, Co, Cu, Hg, Pb, Se, U, V, and Zn) at various concentrations (0, 2.5, 5, 10, and 20 mg/l). Each treatment was replicated four times. Influent and effluent solutions were analyzed using PerkinElmer Optima 5300DV ICP-OES. Removal efficiencies higher than 99% were observed for all metals in the columns operated with limestone for this investigation. We also observed that as the metal concentrations increased in the synthetic solution, more calcium was leached from the limestone columns following an exponential trend. Data support the potential application of natural limestone as a treatment alternative for metals in applications for water sanitation, resource remediation, resource recovery, and industrial wastewater treatments. Further research will be conducted for the use of limestone with higher metals concentrations in order to reach the saturation capacity of the limestone rock.