• Ilje Pikaar

Project Brief

students experimenting

There is a need for cheap and robust methods for decentralized production of drinking water. Ideally, these technologies would be completely independent from electricity from the electrical grid.

This project aims to develop a cheap and robust first proto-type for producing drinking water by means of disinfection using a novel titanium dioxide sheet, which create radicals directly from the sun. The key advantage of this the titanium sheet that it is produced in a unique matter, with a much longer expected service life.

In this context, Fresnel lenses offer great promises. By concentrating solar radiation, one could potentially achieve much higher disinfection rates, as well as much lower required surface areas for the photo catalyst (titanium dioxide sheet).

Previous ICARUS students have provided a proof of concept Fresnel lens (see figure), which will be implemented into the system at later stages to further intensive the radical formation.

In first instance, we will use water from the lake at UQ campus to verify whether the water is efficiently disinfected. In a second stage, a proto-type design for water disinfection at liter scale. Both steps may incorporate the use of the Fresnel lens to further improve treatment efficiency.

diagram of using sun to clean water

Project Report

The second stage of the project started by mimicking the sunlight in the laboratory. A 500W portable halogen light was used. Next the focal point of the Fresnel lens was found. Prior running experiments a shelf system was built. The first test was conducted to analyse the efficiency of TiO2 plate reacting with the UV light emitted by the halogen light. The set-up of the experiment is shown below. TiO2 was placed in a container with 586mg of ammonium per litre of water. The experiment was completed after 8 hours. During the first 4 hours the results of the experiment showed that 50% of ammonium was removed at half of the radiation strength of the sun and without the use of Fresnel lens. Next the same experiment was conducted but this time the Fresnel lens was used to increase the intensity of light. However the results of the second test were not successful. The reasons may be that the material was already passivated or that TiO2 powder was used instead of TiO2 plate. It was concluded that titanium dioxide can work as a bactericidal. Further experimentation might confirm that the increase in the intensity of the sunlight with the use of the Fresnel Lens will accelerate the cleaning water process.

Experimental set-up with Fresnel lens
Figure: Experimental set-up with Fresnel lens.