InStove Water Purifier
The InStove Water Purifier is a biomass-fueled water pasteurizer that is designed for institutions such as schools, dormitories, or refugee camps.
Designed and manufactured by InStove, the InStove Water Purifier is a gravity-fed unit that kills microorganisms by heating water to the pasteurization temperature of 71ºC and cooling it back down to safe drinking temperature. The system is housed in a 60L pot and is designed to work with InStove 60L and 100L cookstoves, but could potentially be used with other heat sources. The flowrate depends on the water inlet pressure, ranging from 3-8 L/min.Interview with manufacturer
East Africa, with field trials underway in Uganda and Zambia
The InStove 60-L Stove retails at $895 USD and the Water Purification unit is an additional $1500 USD (for a total cost of $2395).Interview with manufacturer
Goal 6: Clean water and sanitation
Communities, institutions, organizations, hospitals, refugee camps, and schools
The InStove Water Purifier is manufactured at InStove’s factory in Cottage Grove, Oregon, USA.
The product is in the prototype phase and is not yet distributed.
The InStove Water Purifier is a pasteurization unit with heating coils, a heat exchanger, and regulating thermostatic valve – all housed in a 60L pot and is designed to work with InStove 60L and 100L cookstoves but could potentially be used with other biomass heat sources. Water is gravity fed from an elevated tank (3-4.5 m) and enters into the hot-side of the heat exchanger, then it passes through a coil where it increases in temperature. Next, a thermostatic valve regulates the system by only opening if the temperature of the water is above 71°C. Water then flows through additional piping before re-entering the heat exchanger and cooling down to room temperature as it exists the system.
Some components can be available in local hardware stores, otherwise, contact the manufacturer.
Estimated 10 yearsInterview with manufacturer
The product meets WHO requirements for drinking water while using up to 97% less wood per liter compared to boiling over an open fire.Interview with manufacturer
Laboratory testing was conducted by Oregon State University and found a 99.9999% reduction in E. coli through the pasteurization unit in all samples and an average clean water production rate of 6.7 L per minute. The steady state production of clean water required an average 5.5 g of dry wood equivalent per liter of water pasteurized or 106 kJ of energy per liter. When accounting for system startup, it required 9.1 g of dry wood equivalent per liter of pasteurized water produced or 175 kJ of energy per liter.
Handling firewood and feeding the stove presents a reduced burn hazard compared to a typical open cooking fire. The pasteurization unit is designed to cool the water down using a heat exchanger so that the water at the outlet does not exceed 20 °C and does not present a burn hazard.
The manufacturer specifies that off-the-shelf or purpose-built filters can be connected in-line with the pasteurizer to remove non-microbial contaminants present in a particular water source such as sediments, metals, or synthetic organic compounds.
MacCarty N, Burleson G, Moses N, et al. (2017) Design and Testing of a High-Efficiency Rapid Throughput Community-Scale Water Pasteurization System. ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference.
Meets WHO requirements for drinking water and US-EPA regulations for coliform and virus reduction.Interview with manufacturer
Testing of the fuel usage and pasteurization performance, including following standard protocols for MS2 bacteriophage and E. coli reduction, was conducted at Oregon State University in controlled laboratory conditions. Additionally, field trials were conducted in Uganda and Zambia.Interview with manufacturer
Received the Impact Invention Award from the Lemelson Foundation in 2017.
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