Collaborative Research: Optimization of metal attenuation in biologically-active remediation systems

1336496/1336247科琳·汉塞尔/卡拉·桑特利伍兹霍尔海洋研究所Smithsonian Instants煤炭开采活动造成了世界范围内的环境污染，原因是产生了富含金属的酸性水，破坏了整个生态系统，污染了水供应，危及公众健康。整个阿巴拉契亚地区的煤矿排水(CMD)含有特别高的溶解锰(Mn)浓度，如此高的浓度可能会导致神经疾病。生物活性石灰石处理床是处理含高锰金属的CMD最有前途和经济可行的方法之一。石灰石被用来提高受污染水的pH值，以促进微生物的生长，这些微生物可以(通过氧化反应)将可溶的锰转化为固体氧化锰矿物，然后将其保留在处理床中。这些矿物的形成有效地去除了水中的锰，并产生了用作水处理过滤器的基质，有效地去除了CMD中的其他污染物，如钴、锌和镍。目前，矿山水中锰和其他金属污染物的成功去除是高度可变的，在宾夕法尼亚州的一些系统中，锰的去除效率低至20%。目前，这些处理系统的成功受到对微生物种群的个体和集体活动以及生物介导的氧化锰形成的最佳条件的了解不足的限制。这项研究将通过在受控实验室条件下模拟石灰石处理系统来解决这些知识差距，以更好地建立最有效的生物地球化学条件，以刺激CMD处理系统中的微生物生长和随后的金属衰减。具体地说，该项目将首先确定最有效的微生物种类和营养条件(例如，有机碳和氮组成)，通过实验室中先前从CMD处理系统分离的细菌、真菌和藻类的纯培养和混合培养，促进最佳氧化锰的形成。这些重要的营养和微生物条件将在实验室模拟处理系统中进行使用和测试，以进一步优化复杂微生物组合和关键微生物物种的活动对锰的去除和沉淀效率。在整个实验过程中，将确定影响除锰和氧化锰形成的微生物种群结构和群落相互作用。还将评估生物沉淀的氧化锰矿物的组成和稳定性，以及它们清除金属污染物的效果。制定成功和具有成本效益的方法来清洁受污染的环境和供水是当务之急。该项目将回答限制生物刺激处理过程成功的关键科学问题，并优化目前在世界各地采用的低成本绿色技术，以试图清洁被矿山排水破坏的环境。通过该项目获得的基本知识将被传达给科学家、工程师、教育工作者和政府监管机构，以便直接应用于目前在阿巴拉契亚数百个地点用于处理煤矿废水的石灰石处理系统。该项目的一个同样重要的目标是教育后代和公众关于矿井排水的原因、影响和解决方案。

CBET 1336496/1336247Colleen Hansel/Cara SantelliWoods Hole Ocean Inst. /Smithsonian InstututionCoal-mining activities have resulted in worldwide environmental pollution due to the production of acidic, metal-rich waters that damage entire ecosystems and contaminate water supplies compromising public health. Coal mine drainage (CMD) throughout the Appalachian region contains particularly elevated concentrations of dissolved manganese (Mn), that at such high levels may lead to neurological disorders. One of the most promising and economically feasible approaches to treat metal-laden CMD containing elevated Mn are biologically active limestone treatment beds. Limestone is used to raise the pH of the contaminated waters to promote growth of microorganisms that can transform (via oxidation reactions) soluble Mn to solid Mn oxide minerals that are subsequently retained within the treatment beds. Formation of these minerals effectively removes Mn from the water and also produces a substrate that serves as a water treatment filter, effectively removing additional contaminants, such as cobalt, zinc, and nickel, from CMD. At this time, the successful removal of Mn and other metal contaminants from mine waters is highly variable and as low as 20% removal of Mn in some systems in Pennsylvania. Success of these treatment systems is currently limited by an insufficient knowledge of the individual and collective activities of microbial populations and the optimal conditions for biologically mediated Mn oxide formation. This research will address these knowledge gaps by simulating limestone treatment systems under controlled laboratory conditions to better establish the most effective biogeochemical conditions for stimulating both microbial growth and subsequent metal attenuation in CMD treatment systems. Specifically, the project will first identify the most effective microbial species and nutrient conditions (e.g., organic carbon and nitrogen composition) stimulating optimal Mn oxide formation by pure and mixed laboratory cultures of bacteria, fungi, and algae previously isolated from CMD treatment systems. These vital nutrient and microbiological conditions will then be employed and tested in laboratory-simulated treatment systems to further optimize Mn removal and precipitation efficiencies by complex microbial assemblages and the activity of key microbial species. Throughout the experiments, the microbial population structure and community interactions that impact Mn removal and Mn oxide formation will be identified. The composition and stability of the biologically precipitated Mn oxide minerals and their efficacy in removing metal contaminants will also be assessed. The development of successful and cost-effective approaches for cleaning contaminated environments and water supplies is an immediate priority. This project will answer key scientific questions limiting the success of biologically stimulated treatment processes and optimize low-cost, green technologies currently employed throughout the world in an attempt to clean environments devastated by mine drainage. Essential knowledge gained by this project will be conveyed to scientists, engineers, educators, and government regulators for direct application to limestone treatment systems currently being used at hundreds of sites in Appalachia to treat coal mine drainage. An equally important goal of this project is to educate future generations and the general public on the causes, effects, and solutions to mine drainage. The PIs will integrate this research into two outreach activities, including (1) high school science teacher internships to aid in the development of new curricula that will engage underrepresented students in STEM fields and introduce them to green technologies used to treat environmental pollution and (2) informal presentations and inquiry-based learning exercises at the National Museum of Natural History, Smithsonian Institution, to communicate science activities and products to the general public and provide opportunities for visitors to ask questions and personally interact with the scientists.