Application of High-Activity Modified Green Rusts for Treatment of Water and Wastewater

Treatment of water and wastewater contaminated with compounds such as nitrate and chlorinated organics is a serious environmental challenge. Many treatment processes merely remove them from the water and transfer them to a different material which still must be disposed. Many treatment processes that can economically treat contaminants by destroying them are not effective for some of these contaminants. Those processes that might be able to destroy them by combining them with chemical reductants are too slow to be economical. However, a new chemical reductant called Green Rust has been shown to be an effective way to destroy many contaminants. Furthermore, these compounds can be modified to produce high-activity modified green rusts (HMGR) that can destroy contaminants even faster. HMGR are attractive reagents for water and wastewater treatment because of their low cost and rapid action. The goal of this project is to evaluate the feasibility of using high-activity modified green rusts as reductants for water and wastewater treatment. This goal will be achieved by completing three objectives: a) Develop and characterize HMGR, b) Optimize methods for regeneration of HMGR, c) Characterize behavior of HMGR in various contact systems for water and wastewater treatment. Various methods of producing HMGR will be evaluated. The ability of each potential HMGR to treat two types of contaminants (nitrate, chlorinated organic) will be tested to identify HMGR that are best suited for application in water and wastewater treatment. Other physical and chemical characteristics of the HMGR will be measured to help identify the mechanisms of treatment. An important aspect of applying HMGR to treatment is the ability to regenerate their activity after they have destroyed contaminants. Several potential methods of regeneration will be evaluated. In addition to their reactivity, other characteristics of HMGR are important in applying them to treatment systems. One such characteristic is their ability to be separated from the water to be treated when the water is being treated by a suspension of HMGR. A characteristic that is important when the HMGR contact the water as a film on a solid support is the strength of the attachment to the support. These characteristics will also be investigated. Successful completion of this project will provide the information necessary to determine if application of HMGR to water and wastewater treatment systems is feasible. Furthermore, it will identify for further research and development the most promising kinds of HMGR and the best contact systems in which to use them in treatment systems.