Photocatalysis:Engineering of solar reactors for water purification
Contaminated drinking water is a major cause of disease in developing regions. Diarrheal disease kills approximately 1.8 million people each year and accounts for nearly one fifth of the deaths of children under 5 years old. Solar Disinfection (SODIS) is a simple technique where transparent bottles are filled with contaminated water and placed in direct sunlight for around 6 hours. The combination of solar UV, visible light and heat results in the inactivation of pathogenic microorganisms in the water. SODIS can be effective against the pathogens responsible for cholera, dysentery, typhoid, salmonella, gastroenteritis, cryptosporidiosis, giardiasis and polio. However, some pathogenic microorganisms will exhibit a higher resistance to SODIS treatment.
Photo-excited metal oxide semiconductors have been reported to be effective for the photocatalytic degradation of a wide range of organic pollutants in water and the inactivation of pathogenic microorganisms. TiO2 is particularly suitable for water and wastewater treatment because it is: photoactive, insoluble under normal pH conditions, chemically and photochemically stable, non-toxic, inexpensive and readily available. UV excitation of TiO2 gives rise to the formation of electron hole pairs which can react at the interface of the particle with water and dissolved oxygen to generate reactive oxygen species such as hydroxyl radical, superoxide and hydrogen peroxide. These species are efficient bactericides and can kill a wide range of microorganisms including viruses, bacteria, fungi and protozoa.
The aim of this project is to design, construct and test a pilot scale photocatalytic reactor for operaion under real sun conditions. Pilot testing will be carried out under real sun conditions either at the Plataforma Solar de Almeria in Spain or in India. Previous work using E.coli as the model organism, it was shown that solar photocatalytic disinfection was more efficient than SODIS alone under recirculating batch conditions. UV sensors were utilised to provide feedback control for a gravity feed static batch system and UV dosimetric indicators were tested for application in small volume batch systems. Cost-based analysis indicated that a modular automated batch solar disinfection system was the most promising of the systems tested.
Developments in reactor design and the utilisation of visible light active photocatalysts could make a major contribution in helping to deliver safe drinking water to developing regions.
Personnel Involved
First Supervisor: Byrne, J Dr
Second Supervisor: Brown, A Dr
Collaboration: This project does not involve collaboration with another establishment
Synopsis:
Contaminated drinking water is a major cause of disease in developing regions. Diarrheal disease kills approximately 1.8 million people each year and accounts for nearly one fifth of the deaths of children under 5 years old. The aim of this project is to design, construct and test a pilot scale photocatalytic reactor for operaion under real sun conditions. Pilot testing may be carried out under real sun conditions with our collaborators in Spain.