Danes are used to clean water flowing steadily when we turn on our taps. In stark contrast, a huge proportion of the population in the world's most populous country, India, gets their water from rooftop collection tanks. These are vulnerable to contamination from disease-causing microorganisms, and the water therefore requires purification before it is safe to use.
Njord aqua, a DTU start-up, has set out to ensure people have access to potable water from such tanks with their product, which uses electricity to convert naturally occurring salt in the tank water into chlorine. This makes the water suitable for drinking, cooking and washing.
A vital resource
"When you see these water installations, you sometimes can't believe your own eyes, because they're at optimal temperatures for microbial growth, and some of them are partially uncovered or have holes in them. One of our test users even told us that he had problems with monkeys opening the tank and swimming around in it," says co-founder Andreas Sixten Hallstein Rygaard.
On a reconnaissance trip to India with his business partner Viktor Ryle Tamstorf, he witnessed first-hand the challenges with the water supply there.
The latter is behind the award-winning idea, which was conceived during his bachelor's project and in 2023 was named the best bachelor's project at DTU's student conference for green projects, Grøn Dyst. He continued working on the idea as part of his master's degree.
"There is a massive need for solutions like this in countries such as India on a scale that is simply impossible to comprehend. Water is, after all, a vital resource that we simply take for granted here in Denmark because we have access to groundwater," he says.
Promising laboratory data
Installing the Njord aqua system does not require a specialist, and once it is set up, it can run for years without any interference—unlike if people were to try their hand at purifying the water in their tanks with chlorine.
"Chlorine in bottles or tablets degrades over time and therefore has an expiry date. It is also difficult to dose, and it has to be transported to where it is needed," explains Viktor Ryle Tamstorf, continuing:
"With our invention, chlorine is produced directly in the water right where it is needed. The purification unit continuously purifies the water in the tanks, so the chlorine level in the water remains stable over time."
Laboratory tests show that NJORD aqua's invention can reduce the bacterial contamination in tank water just as effectively as reverse osmosis systems, which are currently the most widespread purification method in India (see fact box). Furthermore, their device requires no more electricity than a solar cell the size of an A4 sheet can generate.
"This way, you are not dependent on a supply chain of consumables such as filters or a power socket, which means our system can also be used in remote locations," explains Andreas Sixten Hallstein Rygaard.
