Arsenic Remediation Using Surfactant Modified Zeolite/Zero-Valent Iron (SMZ/ZVI)

We determined the ability of Surfactant Modified Zeolite/Zero-Valent Iron (SMZ/ZVI) to remove arsenic from municipal water. Arsenic is a common natural groundwater species that has received increased attention due to the EPA lowering of the Maximum Contamination Level (MCL) from 50 μg/L to 10 μg/L. Several batch experiments were run in the lab to estimate the sorption coefficient (K_d), the range of pH the media is effective, and the rate of sorption. All lab tests were performed using synthetic water based on the chemistry of spring water near Socorro, New Mexico. The SMZ/ZVI was mechanically crushed and sieved to a particle size of 1.41mm-2.38mm (8-14 mesh) for all batch experiments.

Lab experiments were accompanied by long-term column experiments using a local water source with arsenic levels at ~40 μg/L. Experimental conditions such as the particle size and flow-rate were varied in the column experiments to find optimal parameters. Influent and effluent arsenic concentrations along with flow rate were measured to calculate the volume of water that can be treated to below EPA specifications.

All arsenic concentrations were obtained using a hydride generation method with Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The batch experiments showed that sorption decreases with increasing pH and that equilibrium sorption is achieved in less than 2 minutes at low concentrations. In addition, a Toxicity Characteristic leaching Procedure (TCLP) analysis was performed and showed that the spent media can be safely disposed in a landfill.