Remediation of heavy metals from contaminated river water using natural zeolite and limestone

Abstract

Acid mine drainage (AMD) is one of the major legacy problems. AMD is the product of oxidation in mine lands and runs into surface water. In this research, the performance of an open limestone channel was examined for treating acidic water by combining neutralization and sorption mechanisms via natural zeolites and lime. AMD samples were collected from Sungun copper mine in the northwest of Iran, and they were subjected to various remediation scenarios. Among the materials used, the zeolite and lime were selected and used to conduct batch and semi-continuous treatment processes. To simulate the water flow of AMD, a physical model was developed. The results revealed that neither zeolite nor lime solely can decrease Cu concentration in the drainage below the permissible level. After installation of the remediation system in Sungun mine, the efficiency of the system was evaluated through two rounds of sampling from the input and output of the system. The results showed a 91% decrease of Cu concentration down to less than 4 ppm at the range of permissible level of surface water. A numerical model that was used to simulate the zeolite treatment system according to laboratory studies estimated the maximum sorption capacity of 2.86 for zeolite and 1.6 for limestone to be 2. 86 mg/g. It was also revealed that the treatment of AMD under zeolite filled channel can decrease Cu concentration below the permissible level in 2 months