Desalinated Water and Stability of Drinking Water Distribution Systems: Behavior of Corrosion Solids and Metal Release Phenomena

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0931676KorshinResearch Objectives and Approach: Use of desalinated water is rapidly increasing throughout the world, but potentially major unintended consequences of its introduction into existing drinking water distribution systems are unexplored. This study will determine mechanisms of corrosion of and metal release from iron, lead- and copper-containing materials exposed to desalinated water and its blends with conventionally treated water. The objective is to determine how gradual or abrupt changes of water chemistry (e.g., pH, concentrations of natural organic matter, NOM, phosphate) associated with the presence of desalinated water affect the formation and stability of corrosion scales and metal release from them. Another target is to determine conditions in which rapid destabilization of such scales can take place. This project will examine these processes based on a consistent approach that addresses: i) transient state and endpoints of corrosion in desalinated water; ii) kinetics of relevant structural transformations; iii) role of colloidal phenomena and NOM and iv) specificities of action of corrosion inhibitors. Work will be carried out using two modes of corrosion exposures with copper, iron and lead-containing-materials. Experiments with scales pre-formed in conventionally treated and exposed to desalinated water, and representative individual solid phases will also be carried out. Methodologically, the study will rely of diverse methods such as XRD, SEM/EDX, colloidal (size distribution, æ-potential and sequential filtration) measurements coupled with analytical determinations. Advanced experimental and interpretative methods will be used to generate knowledge that is indispensable for successful long-term use of desalinated water, a technology that plays an increasingly critical role in global sustainability. The intellectual merit of this project is based on 1) novel approaches to ascertain mechanisms and quantify contributions of physico-chemical processes (structural transformations, colloidal disaggregation and others) that are specific to desalinated water; 2) elucidation of critical indicators of the composition of corrosion scales that determine their instability and 3) development of approaches to prevent major metal release episodes in desalinated water. The applicants believe, to the best of their knowledge, this study is the first to address these issues based on fundamental science. This study will provide insight into issues that are increasingly important and visible not only for environmental professionals but for the general public in this country and globally. Results of this project will ultimately help protect public health and ensure sustainable functioning of drinking water infrastructure, a matter of great societal and economic concern. This project will also contribute to training, mentoring and overall development of the UW students, including their exposure to international issues via cooperation with Australian partner institutions, notably Australian Water Quality Centre in Adelaide. Results and techniques of this study will be integrated into the engineering curriculum at the University of Washington, presented at UW Undergraduate Research Symposium and to the general community at the UW Engineering Open House and BRIDGE seminars. The graduate students will enhance their mentoring and teaching abilities by interacting with the laboratory undergraduates, and by presenting their research at seminars and conferences. Elements of this research will be incorporated in an international project-based course (jointly with Tohoku University in Japan) for engineering freshmen. To increase the participation of underrepresented minority and women students in Engineering at the University of Washington, they will leverage the resources of the College of Engineering Advising and Diversity Center with whom the group has partnered in the past.