cover the feces in ash, which speeds up the
In addition to functionality, the other
key part of the diverter’s design was its aesthetics. Sanivation wanted to minimize the
need for behavior change to ensure people
would actually use the toilets; Woods says
research has proven that people are more
willing to try and use nice looking products.
In trying to build a diverter that could easily
work for men and women, the team found
that standard funnels were unattractive,
but custom molded plastic diverters were
too expensive. They eventually settled on a
diverter made of sheet metal.
“When you paint the sheet metal it looks
nice, but it costs about $8 to make one, so
it’s expensive,” says Woods. “We have been
working with design students and got some
free consulting hours from Catapult Designs,
so at some point, we might have an injection-molded design that looks nice and is cheap on a
CON TINEN TAL SHIF T
In spite of grappling with certain design
aspects of the Blue Box, the product is far
simpler than their initial idea for a solar
toilet. That concept originated back in 2011,
when Woods and Foote first started experi-
menting with sanitation solutions—in Chile.
At the time, the Chilean government-funded Start-Up Chile was accepting
applications for early-stage entrepreneurs to
bootstrap project ideas in Santiago. Woods,
Foote and a few other engineers applied and
were accepted to the program.
Their idea was for a dual-vault latrine
that had a solar “oven” hitched to the back.
But the cost of such a toilet was too high
for most of their intended demographic to
afford. Additionally, rapid urbanization was
eating up land that might have otherwise
been available for a large, all-in-one latrine.
And, as many of their potential clients were
renters, they did not get a lot of interest
in what was effectively a home investment. Woods and Foote turned instead to a
What the team then needed to figure
out was how to neutralize pathogens in the
waste they planned to collect. After many
design iterations, the team built a solar
concentrator that was both effective and
affordable. However, Woods says the lack
of scientific literature on deactivating fecal
pathogens left them with a lot of questions
about how to render the poop safe. They
focused on certain parasites found in human
feces called helminthes, and determined
that if they could eliminate one in particu-
lar—Ascaris lumbricoides, an intestinal worm—
then they would have a reliable system.
A grant from the U.S. Centers for Disease
Control and Prevention (CDC) allowed them
to experiment with different time and temperature combinations, and they eventually
settled on the 65-degree and 85-degree
benchmarks that they currently use.
Having a weather-dependent system has
limitations, however. Woods says she is
currently working on a continual flow heat
treatment that she expects to be ready for
use sometime in 2016. For this process, they
will use solar energy to warm a heating fluid,
which will be kept at a steady temperature.
They will then treat the feces over the fluid
instead of directly in the sun. This process
will allow Sanivation to treat a much higher
volume of waste.
What Woods and Foote realized through
their work in Chile was that although they
had put all the pieces together for a workable
sanitation business, there was no market for
FIG 4: Sanivation’s service model
Drying Heating Mixing
WASTE COLLECTION STEP 2: WASTE TREATMENT & TRANSFORMATION STEP 3: AFFORDABLE FUEL