Sustainable Drinking Water Adsorptive Materials for Arsenic and Fluoride Removal in Emerging Regions

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

1066425 Sabatini There is a global water crisis, as the United Nations University estimates that approximately 900 million people (nearly a seventh of the world's population) currently lack access to potable water. Naturally occurring contaminants such as arsenic and fluoride contribute to this crisis, causing severe health problems above World Health Organization (WHO) recommended levels. Treatment of arsenic and fluoride contaminated waters is especially challenging in the developing world since over 1.4 billion people live on less than $1.25 per day according to the WHO. Commercial water treatment materials used for arsenic and fluoride treatment in the U.S. are expensive even by U.S. standards, putting them out of reach for remote villagers in low income countries. A great challenge thus exists to develop materials that approach the efficiency of commercial materials for arsenic and fluoride removal from drinking water supplies, but that are much less expensive and that, ideally, are produced in the developing country. An equal challenge is to develop materials that are sustainable in terms of both environmental impacts across the life cycle and adoption and long term implementation in country. Intellectual Merit. The overall objective of this research is to utilize colloid and surface chemistry principles to produce effective and sustainable water treatment materials for arsenic and fluoride removal in developing countries. Currently available materials suffer from high cost (e.g., granular ferric oxide and activated alumina) or poor sorption capacity due to low surface area (e.g., iron coated sand). To address these challenges, high surface area chars will be generated from organic biomass (locally available plants and trees) and coated with iron and aluminum minerals that have high affinities for arsenic and fluoride, thereby producing adsorbents with both high surface areas and high sorption affinities. Mineral coated chars will be characterized with respect to the size and distribution of mineral particles in the chars, and the depth of penetration of mineral particles into char pores. These properties will then be correlated with sorption performance. Batch and column sorption studies with mineral coated chars will be conducted, both in the presence and absence of potential competing anions, in order to identify those with the greatest sorption affinity for arsenic and fluoride under realistic conditions. Desorption and leaching studies will also be conducted to evaluate the suitability of regeneration or permanent landfill disposal of spent mineral coated chars. These laboratory experiments will be followed by comparative evaluation of the most promising mineral coated chars in terms of environmental impacts across the life cycle using life cycle assessment, and development of a sustainable implementation plan for local adoption of these materials using the principles of social entrepreneurship. The last component of the proposed work is to test, in collaboration with non-governmental organizations and Dr. Feleke Zewge at the University of Addis Ababa, the most promising mineral coated chars for fluoride removal in a rural village in Ethiopia impacted by high fluoride in its water supply. Broader Impacts. The results of this research will be disseminated to the scientific community through publications in refereed journals and to several governmental and non-governmental organizations. Research results will also be integrated into two senior/graduate engineering classes, an interdisciplinary undergraduate honors class on water and sanitation in remote villages of developing countries, and a business course focused on social entrepreneurship. Research students will present papers and undergraduate students in the multidisciplinary honors class will present posters at the biennial University of Oklahoma (OU) International WaTER conference in order to further disseminate the results among the international community of researchers and practitioners. Educational materials developed for these classes will be submitted to the K-Gray Engineering Pathway Digital Library (a national repository for K-gray educational materials in science and engineering) and their public availability to other educators will be advertised widely. This research topic is popular for undergraduates, and, based on experience at OU, attractive to underrepresented groups in science and engineering. By improving health in the most impoverished regions of the world, the research results will enable education and development in regions historically plagued with unrest. Finally, developing novel water treatment materials and evaluating their use in terms of both adsorption efficiency and economic and environmental sustainability will lead to new applications appropriate not only for the developing world, but for the U.S. as well. This award is co-funded by the CBET/ENG Environmental Sustainability and Chemical and Biological Separations programs, and the NSF Office of International Science and Engineering.