What is Solar Water Purification?

Solar energy can be used in a number of ways to purify water for human consumption. The main methods are either photochemical process or thermal treatment.

Technologies

Photochemical Process

Photochemical processing requires a photoreactive catylist be introduced to the water. Commonly titanium dioxide or hydrogen peroxide are used. In the case of titanium dioxide, the compound can be used as a coating on the base of the treatment container. Incoming solar energy reacts with the compound to create singlet oxygen or hydroxil radicals which break the bonds of the toxins in the water thus purifying it.

Thermal Treatment

Thermal treatment comes in two forms as well. Thermal oxydization and the older and less expensive solar still.

Thermal oxydization requires very high temperatures, and so requires a solar concentrator system such as a parabolic trough array.

Solar stills are simple apparati consisting of a basin covered by an inclined piece of glass or other transparent material and a collection trough. Water is pumped into the basin where it is heated by the sun till it evaporates. The vapor condenses on the inclined cover where the droplets flow to the collection trough. Solar stills are very simple and inexpensive in construction. A small three gallon per day system can be built for $200-$300. This type of system has been installed in several small towns along the Texas-Mexico border to provide safe drinking water for the communities.