Procurement of clean drinking water is one of the most important challenges facing 1 in 10 people in the world today. While there are many technologies available to disinfect water, there is still great opportunity for appropriate, sustainable technologies for low-resource or emergency situations. Pasteurizing water is an effective way to eliminate life-threatening pathogens such as bacteria, viruses, and protozoa, and requires a lower temperature (71° C) compared to traditional boiling (100° C).
This research details the development and testing of a water pasteurization system that works with the 60 Liter InStove to produce upwards of 4,500 liters of safe drinking water per day at minimal cost to the users and the environment. This flow-through system uses a combination of a heating coil, thermostatic valve, fixed volume kill chamber, and heat exchanger for heat recovery immersed in a large pot of heated water. Initial performance testing revealed that the pasteurizer produced 6.7 liters of water per minute with an energy input of 9.1 grams of equivalent dry wood per liter (175 kJ/L) at steady-state operation accounting for startup time. Microbiological testing revealed that water initially inoculated with >100,000 bacteria/ml of E. coli had no colonies remaining after treatment, for a 99.999% reduction in contamination levels. Future work will include measurement and modeling of the flow and temperature profiles throughout the system to optimize its heat transfer performance and production costs, field testing, and user-centered system-level design that develops the end-to-end solution needed to acquire and deliver clean drinking water including maintenance, container disinfection, and development of business models to support local water production.