The solar water purification system works according to the so-called photo-Fenton process, in which water is purified with the help of solar energy and photocatalysts such as iron salt.
The wastewater plant for catalytic wet oxidation purifies water through UV oxidation, using two 10-kilowatt mercury medium pressure lamps and an oxidising agent such as hydrogen peroxide or Caroat (potassium peroxymonosulfate). The maximum throughput is 10 cubic metres per hour.
At its Lampoldshausen site, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) operates test facilities for space propulsion systems, with different processes generating wastewater that is contaminated with various pollutants. This wastewater is fed into an industrial drainage system and carried to the N39 decontamination plant for treatment to neutralise the pollutants.
N39 is responsible for treating wastewater that may contain carcinogenic hydrazine derivatives and toxic cyanides and nitrites. This means it must be detoxified before it is fed into the local water system.
Biological treatment methods using microorganisms cannot be used on these types of pollutants, so at N39 the wastewater is purified by a combination of photolysis (using UV-C radiation) and an oxidising agent such as hydrogen peroxide or Caroat (potassium peroxymonosulfate). In this system, the substances that need to be eliminated either directly absorb radiation and are thus destroyed, or are degraded by the UV-activated oxidising agent.
Solar purification system for polluted wastewater
A solar-powered part of the plant, called 'SOWARLA', is used to rid wastewater of most organic and some inorganic impurities via photocatalysis. Toxic substances that are difficult to break down biologically are thus destroyed by sunlight and a photocatalyst. At the heart of the facility is an innovative, efficient solar receiver module made of transparent glass tubes.
The solar water purification plant uses the photo-Fenton process, which cleans water using solar power and photocatalysts such as iron salt. The polluted water is mixed with the catalyst and the oxidising agents, exposed to sunlight via the solar receiver and then pumped around the cycle until it has been decontaminated. Water purified in this way can then be disposed of or reused.
Unlike conventional solar reactor concepts, SOWARLA is very easy to install and highly versatile, making it suitable for large-scale applications and diverse conditions. SOWARLA saves around 90 per cent of the energy used by other contaminant removal processes and requires significantly fewer oxidising agents.
Contact
Volker Speelmann
Head of Research Infrastructures
German Aerospace Center (DLR)
Executive Board department for Innovation, Transfer and Research Infrastructure
