If water could be cleansed using only sunlight and a reusable substance, then we could solve two problems in one go: Our water would be free of pollutants and the environment protected from the influence of harmful chemicals. How could this work?

To find this out, we will pollute some water with formic acid or a dye and add a catalyst. Together, the catalyst and the solar radiation activate a photochemical reaction that produces astonishing effects. Solar water purification can also be employed on an industrial scale. The solar reactor that you will be working with is being developed for industrial use. But why are we interested in developing a different way of cleansing water?

Clean water can no longer be taken for granted

Clean water can no longer be taken for granted. Credit: DLR (CC-BY 3.0)

Water is vital – but clean water can no longer be taken for granted! The amount of harmful substances has increased greatly and with them the challenges science faces in upholding our environment. Solar water purification is a new, environmentally-friendly method that enables us to systematically reduce pollutants.

How does solar water purification work?

How badly does our test pollutant actually pollute the water? And could we not just use the sewage works? Microorganisms eat “dirt”. But what happens if the “dirt” is toxic to the microorganisms and they are killed?

Apparatus for solar water purification

Apparatus for solar water purification. Credit: DLR (CC-BY 3.0)

Solar water purification could be a method with which a wide range of pollutants could be removed. Perhaps Grandmother’s method of bleaching the washing in the sunlight was not such a bad idea ...