Project Summary

Streams contaminated by acid mine drainage (AMD) are complex environmental systems which require biological, chemical, and physical treatment steps for thorough remediation. In this work, a novel concept for treating AMD is investigated, in which the biological reduction of acidity, chemical enhancement of alkalinity, and physical sorption of metals occur simultaneously using one multifunctional substrate: chitin from crab shells. The location of the proposed work, the abandoned coal-mine discharges of central Pennsylvania, lends itself perfectly to the seamless integration of research and education in this project. This project supports the development of a new “Field Methods for Remediation Design” course to be offered to undergraduate and graduate students. The students in the field methods class will partner with high school students from an AMD-affected watershed, and together collect field samples that will be used to support the research of the study.


Intellectual Merit

This is the first investigation of its kind, wherein one material is examined for its comprehensive ability to sustain biological, chemical, and physical remediation. Many multi-component waste streams could potentially benefit from the application of such a material, and several materials could likely serve as multifunctional substrates. In this study, crab-shell chitin is examined as a multifunctional substrate for the simultaneous treatment of acidity, sulfate, and metals contamination in AMD. The PI has previously demonstrated that chitin is an effective, slow-release carbon and nitrogen source that can support a diverse community of microorganisms, as well as naturally buffer pH, reduce metals, and maintain its permeability during degradation. Together, these properties make chitin ideal for use in passive AMD treatment systems. To examine the key parameters that make chitin an effective multifunctional substrate, several tools are needed. Others have used sorption isotherms to study chitin as a biosorbent of metals for industrial water treatment, although the competitive biosorption and ultimate fate of the metals found in AMD has yet to be examined. Although much effort has gone into characterizing the microbial communities in AMD habitats using culture-based and genomic techniques, the development of key populations within passive treatment systems has not yet been investigated. The proposed research will be the first to examine the ultimate fate of metals and the development of a microbial community within a passive AMD treatment system. This will be accomplished using sorption isotherms, chemical equilibrium modeling, and comparative metagenomics to better understand the multifunctional dynamics of AMD treatment using chitin in comparison to other, currently popular, but underperforming, substrates. This research is a necessary first step to understanding the comprehensive capabilities of multifunctional substrates and improving the design of AMD treatment systems.


Broader Impacts

The broader impacts of this project are educational, environmental, and economic, and range from local to global in scale. In addition to supporting the research of multiple minority graduate students, the proposed activity promotes the teaching, training, and learning of graduate and undergraduate students through the development of a field methods class, with outreach to economically-disadvantaged high school students living in an AMD-affected watershed. The 19,000 kilometers of AMD-affected streams in the United States require an estimated $72 billion to remediate: a currently insurmountable expense. The development of cost-effective multifunctional substrates for AMD treatment could provide environmental and economic benefits. Once chitin is applied in the proposed field demonstration, beneficial environmental impacts should be felt in the local watershed and improve the water quality of endangered downstream watersheds such as the Susquehanna River and the Chesapeake Bay. Chitin treatment of AMD could similarly have a positive impact on the environment and economy throughout the world. Finally, the treatment of AMD using chitin may serve as a model for the treatment of mixed waste systems using multifunctional substrates, to be examined in future work.


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