Solar Powered water purification in Tanzania
February, 20th 2020
Worldwide, one in three people lacks access to safe drinking water, according to the most recent data from the World Health Organization (WHO). The problem is acute in many low-income urban regions, such as Dar es Salaam, a major city and commercial port on Tanzania’s Indian Ocean coast. Here, rapid population growth has led to 70% of the population living in unplanned settlements where there is no safe water infrastructure.
Low- and middle-income populations in Dar es Salaam have come to rely on private water vendors, who either sell unclean municipal water at a high mark-up, or expensive bottled water at a low profit margin.
The system hardly works for anybody, says Michael Coto, co-founder of Majico – a spin-out from the University of Cambridge, UK. ‘The people selling the bottled water are typically small-scale vendors who complain that they don’t make much money, while the people who buy the bottled water complain of the expense of buying it,’ he tells Chemistry World.
Coto is trying to help both parties in this dilemma by providing the vendors with solar powered water purifying kiosks that allow them to produce and sell clean water in their own communities. The idea, Coto says, is to undercut the price of bottled water for consumers, while increasing the profit margins of the vendors.
All that it requires is sunlight, photocatalytic material and a humble microwave. The photocatalytic material is made using silver nanoparticles. ‘Certain reducing agents combined with heat treatments produce very, very small metal nanostructures,’ Coto says.
Majico most commonly uses silver, which has a powerful antibacterial effect. ‘We can produce nanoparticles that are less than 1nm in diameter. That gives us high photoactivity and also kills bacteria exceptionally well.’ In order to keep production costs low, Coto developed a method to heat the material using a microwave or a standard kitchen oven.
With this technique, Majico can build a hub in Tanzania that will manufacture and maintain the systems on the ground. ‘We make the catalytic materials in a frugal way because we try to make it as simple as we can,’ Coto explains. ‘Ultimately, we want to make these materials and the end product locally, in a low-cost setting.’ That’s the commercial incentive, he says, but ‘our social mission is to increase access to affordable drinking water.’
Source: chemistryworld.com