Membrane systems are gaining in there applicability to many environmental engineering science solutions. The goal of this research is to develop bipolar membranes suitable for use in environmental applications. Bipolar membranes are a technological marvel and have p-n junctions similar to those in transistors. This process will remove salt from the water and will eliminate the use of acids and bases for ion exchange regeneration, thereby eliminating a major source of salts in public water supplies. Although bipolar membranes have been commercially available for more than 20 years, they have not gained widespread usage due to the limitations of commercially available membranes. Commercially available bipolar membranes are not well-suited for environmental applications, and can be improved by increasing their stability in high pH solutions and decreasing the voltage required for water splitting at low current densities. Membranes developed for alkaline fuel cells have shown exceptional stability at high pH values and may be suitable for producing bipolar membranes for environmental applications. Replacing the catalyst layer with an electrically conductive interlayer in the center of a bipolar membrane may decrease the width of the p-n junction and decrease the water splitting voltage at low current densities. This research will investigate the use of highly stable poly(biphenyl alkylene) anion exchange membranes and electrically conductive interlayers for use in bipolar membranes. With only 1 volt of applied polarization, bipolar membranes can split water into H+ and OH- ions at rates that are more than 7 orders of magnitude greater than the rate in bulk water. Despite their commercial availability since 1977, bipolar membranes have not attained widespread industrial use. Bipolar membranes have been studied at the laboratory and pilot scale for a wide variety of applications, including: production of mineral acids from salt solutions, recovery of organic acids from fermentation broths, pH control in biochemical processes, recovery and purification of pharmaceuticals, de-acidification of fruit juices, and energy storage and conversion. Two impediments to greater use of bipolar membranes are the low stability of strong-base anion exchange membranes under alkaline conditions and that commercially available membranes are not optimized for the requirements of many potential applications. The PIs hypothesize that the base stability of the anion exchange component of bipolar membranes can be improved using alkaline stable hydroxide conducting membranes developed for use in alkaline fuel cells. Additionally, we propose that a new type of bipolar membranes with an electronically conductive interlayer region will be useful in a variety of industrial applications where commercially available membranes are ill-suited. The research proposed here will develop alkaline stable bipolar membranes with electronically conducting interlayer regions that are suitable for use in water treatment applications. Aside from the scientific impact of this research will be the production of better bipolar membranes that will be useful in a wide variety of applications. The area where bipolar membranes can make the biggest impact is in water treatment. Bipolar membrane electrodialysis can be used to both desalinate water and to provide the acid and bases that are commonly used in water treatment applications, such as: ion exchange regeneration, coagulation, scale inhibition, decarbonation and pellet softening. Eliminating the use of acids and bases in water treatment will alleviate the problem of salt accumulation in groundwater and other public drinking water supplies in arid regions. The project will support the training and development of one doctoral student and several undergraduate students. In addition, post-doctoral scholars from Mexico supported by the CONACyT program will be integrated in this research. Finally, an education and diversity plan will focus on recruiting students from under-represented groups and integration of research results into the Fundamentals of Electrochemistry Class that is currently being taught.