Project Brief
Longido is a town in the Northern region of Tanzania that has a chronic water shortage. We worked alongside the faculty of Environmental Engineering and the Sprott School of Business to create a solution that would be both affordable and viable for the local Maasai people while addressing the clean water issue.
Initial Research & Sketches
Initial designs covered a wide variety of water-related design solutions. I chose to pursue the design of a solar still that would allow greywater to be purified by the power of the sun.
A small sample of the research that was done trying to learn as much as I could about a different culture and the resources available to design with.
Research Trip
In order to do some first hand research and talk to the local Maasai people I took a trek to Tanzania with some classmates to get initial feedback on our ideas and do some prototype testing.
Local business in Longido that purified water using clay pot filters.
A traditional boma-house the rural Maasai live in.
Assembling the Prototype Solar Still
A solar still works on the principles of evaporation and condensation, like the rain cycle on the earth. This cycle purifies the water because only pure water evaporates, condensates on the top surface of the still, and is collected. The dirt and bacteria remain in the basin of the still and can be disposed of later.
Assembling the first prototype in Longido.
The first prototype out in the Longido sun, hoping to see it work.
End of day 1 of testing. Success! The water is condensing on the top surface and dripping down, though it is not being collected properly and is going everywhere, including back down into the dirty basin.
Back in Canada
From the first prototype I tested in Tanzania I had proof of concept that the solar still could use the power of the sun to purify greywater. The next step was to start designing the final product trying to use local materials.
Solar Still Version 2.0: After seeing many 5 gallon pails being used for water all over Longido, I reasoned that it could be used as a 'base unit' to build my solar still on. I would just ship the top unit, containing a dome and a basin for the dirty water and residents could buy the 5 gallon pail locally for about $1.50 US.
How it Works
Leftover greywater (from laundry, etc.) is put into the feedwater tray at the top of the pail. The dome lid is then placed on the the still and is left to sit out in the sun all day. Evaporation occurs in the dirty greywater, which then condenses and runs down the dome to collect in the bottom of the pail. At the end of the day residents simply take off the dome and they have a pail with the purified water.
Since it was -30 Celsius outside I had to do some improvisation during testing since I no longer had access to the Tanzanian sun. The kettle is putting out steam which I used to test the condensation and drip pattern of my new design.
You can see here the dome shape was more effective than the slope of the prototype I tested in Tanzania, but it is only effective to about halfway. The drips that form on the top half run back down into the dirty water which is decreasing efficiency.
User testing to determine the best way to fill the still with greywater.
The Path Forward
While I liked the form factor and projected cost of the 5 gallon pail solar still there was one large issue. The output was projected at only 1 litre of clean water per day. To make this viable residents would need to own many solar stills. So it was time to go back to the drawing board and building off what I had already learned I started on version 3.0
At this point Virginia from TEMBO had the idea to use the ubiquitous laundry tub as the new base unit. This is perfect because it is larger and also readily available locally.
Back to the drawing board to imagine how the still would look if it used the laundry tub and local materials such as bricks, concrete, etc.
Final Design Direction
The sketch on the top left hand side of the previous page turned out to be a key sketch. Though it was fast and rough it had the idea of the cone on top of the laundry tub. The tub would sit inside a vacuum formed plastic basin on a stand which would allow the clean water to be retrieved via a spigot at the bottom.
Use cycle of the new solar still design.
Early rendering of the final design direction. Visualised here in Longido, Tanzania.
Building the Final Prototype
Once the final design was complete it was time to CAD out the solar still, produce some renderings, and build the final prototype.
Solidworks section view of the solar still.
Exploded view.
Shop time! Lathing, CNC cutting, and vacuum forming the parts. I chose to build a half scale model for my final prototype.
Let's put the final prototype to the test before putting on the finishing touches. Shown here is the muddy feedwater.
It's working beautifully! You can see the clean water condensing on the cone and dripping down into the reservoir.
And the ultimate test: a taste of the purified water. The verdict? Not bad at all.
And here is the final prototype painted and finished.
Showing the various components.
Visualization of the solar still in use at the TEMBO guesthouse in Longido, Tanzania. The projected output for the solar still is about 3-3.5 litres per day of purified water using only the power of the sun. Once the still has been purchased there are no running costs which allows people to buy less clean water and spend that money on food or other items needed, especially during the long dry season.
The end!
Special thanks to the many who helped out along the way: Professor Bjarki Hallgrimsson, professor Chantal Trudel, Troy Anderson, Onita Basu, Virginia Taylor, Alanna Brunskil, Avery Price, and my classmates.
