0239314 Marchand The research described in this proposal aims to study methods for minimizing acid formation in situ by stimulating heterotrophic microbial growth. It is hypothesized that if given the appropriate conditions (namely, a degradable organic carbon source), heterotrophic bacteria will be able to out-compete the iron-oxidizing microbes responsible for catalyzing acid-forming reactions at acid mine drainage (AMD) sites. This is an area that has not achieved much attention and has the potential to be utilized as both a remediation and prevention technique. The proposed research will provide fundamental understanding of microbial community structure in a model extreme environment; however, results may be transferable to community dynamics in other extreme environments that are subject to similar constraints. This investigation will experimentally evaluate the influence of supplemental organic carbon substrate addition on mineral oxidation in fractured or biofilm-based systems. The specific objectives of the research are: 1. Identify the influence of enhanced heterotrophic microbial growth on mineral oxidation by acidophilic microbes in laboratory systems with a high surface area to volume ratio. 2. Establish the mechanism(s) involved in heterotroph-induced prevention of acid generation and determine the appropriate conditions to enhance heterotroph-induced prevention of acid generation in biofilm-dominated systems. 3. Identify the relative influence of microbial iron and sulfate reduction in acidic environments for bioremediation of acid mine drainage. 4. Assess the influence of organic carbon substrate addition on acid generation at a well-characterized AMD site. The long term and broader scientific and engineering impacts of the proposed research involves the development of new methods for both prevention and mitigation of acidic drainage. While current applications focus on treatment of acidic, metal-containing water streams - typically utilizing chemical precipitation - the proposed research will attempt to prevent acid formation in situ before treatment is required. While a primary goal of the proposed research is to prevent acid generation from occurring in the first place efforts will also be made to identify the efficacy of achieving in situ iron and sulfate reduction, particularly in low temperature environments. Scientific outreach activities associated with this project will include participation of the PI in regional public meetings aimed at educating the public about issues associated with acid mine drainage. The PI has already developed a working relationship with regulators and water quality scientists at the California Regional Water Quality Control Board - Lahonton Region and will work with these individuals to disseminate experimental results. The broader education-based implications of this research involve the development of interactive experiments for incorporation into the Mobile Engineering Education Laboratory (ME 2 L). Funds are requested to support undergraduate students while they design and build interactive displays for the mobile lab. In addition to their utility for the ME 2 L program, these demonstrations will also be incorporated into Engineering Day and the Science Day programs at UNR, two programs aimed at getting High School students to think seriously about careers in science and engineering. In addition to these outreach-based education goals, the PI has also proposed to develop an undergraduate and graduate coursework series in environmental engineering that introduces fundamental and applied aspects of environmental microbiology in an engineering curriculum.
