STTR Phase I: Design of Diffusiophoresis Processes for Drinking Water

The broader impact of this STTR Phase I project will be to improve water purification with a new process offering reduced costs. Currently 1.8 billion people worldwide drink feces-contaminated water, of whom half a million die from waterborne diarrhea annually. The proposed technology also will reduce capital costs in more developed areas as it eliminates the need for pumps and filtration membranes. The modular nature of the process equipment makes it scalable, from the modest requirements of isolated rural communities not served by distribution networks to the largest-scale throughputs of utilities serving major cities. This technology advances new methods for drinking water purification leveraging new research in fluid mechanics and electrokinetics. The suitability for drinking water purification of a diffusiophoresis process needs to be proven in the presence of complex chemistries representative of water streams with multiple dissolved impurities, and for the removal of colloidal contaminates, including bacteria. Experimental results spanning a range of parameters need to be obtained and tested against mathematical models, to establish design rules for scale-up. A laboratory experimental program, supplemented by mathematical modelling for quantitative understanding, aims to: (1) establish process feasibility and latitude in practical, ‘multi-ion’ environments; (2)map device dimensions, particle characteristics, water chemistries, particle removal efficiency, CO2 required; (3)demonstrate removal of colloids such that membranes will be at minimum significantly ‘unburdened’, and of bacteria such that chemical treatment can safely be at minimum significantly reduced; (4) determine process parameters and values for varying colloidal and microorganism loads. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.