Study of factors to improve the removal of trace metals/elements from mine effluents using low-cost adsorbents

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The contamination of surface waters and soils by toxic trace elements from mining and other industrial activities is a major environmental problem. In the meantime, the production of large quantities of waste materials generated by various industrial activities also becomes an ever-pressing issue as they not only cause a secondary pollution and aesthetic problem, but also occupy vast areas of precious land. The safe storage and handling of these wastes is very costly. In this proposal, we present a research plan to address these two problems simultaneously, by specifically turning waste materials into valuable resources and using them as effective materials to remove toxic elements from mining wastewater or to immobilize them for soil remediation. In some previous work, we found that coal fly ash, drinking water sludge and red grape pulp can be used as primary low-cost adsorbent materials for toxic metals and elements. Furthermore, impurities in these wastes are very low and generally not releasable in solution, thus making these materials suitable as primary adsorbents. Solution pH is a critical factor to consider and at optimal conditions, the adsorption capacity of the studied materials were generally high and the kinetics of adsorption relatively fast. In this proposal, we intend to enhance our knowledge of the modification conditions of these materials to further enhance those parameters. Our objective is to make the modification processes simple and at low cost. Additional studies on the adsorption properties of metals with agricultural wastes and in combination with modified fly ash will be done in more detail to reach maximum adsorption capacity and retention by these low-cost materials. The possibility of molding efficient adsorbents to make them easy to handle will be tested. The formulation should be economically sound and the adsorbent material could be reused multiple times. The ultimate goals in this study are to: (1) develop low-cost combination of adsorbents for the removal of toxic elements from mining waters; (2) use these adsorbents as passivating agents to immobilize toxic metals in soil and prevent them entering the food chain; (3) determine if the materials used in mine treatment plants can be reused. To achieve these goals, systematic chemical experiments will be conducted on the properties of different materials both alone and in combination in order to maximize their potential for use in an industrial mining setting or other contaminated environments. Several analytical techniques and instruments will serve as detection tools. The mechanical resistance of molding material will be evaluated under calibrated press and other instruments.