Years of uranium mining on the Navajo Nation Reservation during the Nuclear Arms Race have left behind numerous unremediated uranium mines. These mines provide a conduit for meteoric water to infiltrate uranium-containing sandstone underneath and mobilize the radioactive element. These contaminated waters eventually return to the surface where they are consumed through unregulated private wells by people, livestock, and used for agriculture.
An easy and cheap treatment method for filtration of heavy metals such as uranium is therefore necessary. By using limestone to lower uranium solubility and mobility and walnut shells to incite uranium to adsorb to the nut shells, a new method of treatment was devised and examined. Three types of filters were tested based on setup of these two materials, and most were successful in lowering uranium concentrations to below the EPA uranium maximum contaminant level of 30 ppb. More studies must be done to determine whether activation of walnuts is necessary for treatment.