Solar power

Development of photocatalytically coated solar receiver reactors for water purification

Pretreatment of heavily polluted waste water currently requires the use of harmful chemicals and a large amount of energy. As part of this collaborative project, the partners are aiming to develop a water treatment method using solar photocatalysis. They are testing a coating based on titanium oxide (TiO2) in terms of its photocatalytic activity and its adhesion. 


Process water from industry is often contaminated with persistent organic material and cannot be fed into a biological clarification stage without pretreatment. In the past, oxidation methods and UV light have been the established waste water treatment solutions.

The project will study the potential for waste water treatment using solar photocatalysis, which could save 80-90% of the energy and up to 100% of the oxidant compared to the UV oxidation method. To achieve this, a TiO2 coating has been produced in glass tubes as photocatalyst and its use for water purification investigated. The tubes are part of a water purification reactor with non-concentrating solar receivers as the energy source. Environmental pollution from using UV light sources containing mercury can be avoided.


  • A simple coating method for glass tubes was developed and optimised.
  • A single coating is sufficient if the optimum sol is selected.
  • As well as for degradation of methylene blue, the purification effect was also confirmed for the antibiotic sulfamethoxazole as a benchmark test.
  • The selected tube diameter was kept as small as possible to obtain the largest possible ratio between the catalyst coating and the receiver volume.
  • Salts contained in the water have no negative influence on purification capacity.
  • Tensides can lead to detachment of the catalytic coating. A laboratory test confirmed that tensides interfere with the degradation of the antibiotic sulfamethoxazole.
  • Photocatalytic degradation of sulfamethoxazole was also confirmed outside the laboratory in a pilot photo reactor.
  • In addition, it was demonstrated that the purification effect is retained over a winter period with corresponding alternate freezing and thawing.
  • The solar reactor is less effective than the TiO2 suspension but the problem of complicated removal of the TiO2 from the purified waste water is avoided.

More Project Informations

Project title:  Entwicklung photokatalytisch beschichteter Solarreceiverreaktoren für die weitergehende Wasserreinigung (SolPur)

Project number:  01LY0814A-C

Project period:  2009 - 2011

Project region:  Germany (Baden-Württemberg)

Project contact:

Herr Dietrich

This email address is being protected from spambots. You need JavaScript enabled to view it.

+49 (0) 7132 3818-109

+49 (0) 7132 3818-703


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Source: German National Library of Science and Technology Hannover (TIB)