Annual Report 2006 - Plataforma Solar de Almería

ENVIRONMENTAL APPLICATIONS OF SOLAR ENERGY
Duration: January 2006 - December 2009
Background: This work concerns the development of a new system for treatment
of dangerous and toxic substances, such as H 2 S, mercaptans, etc.,
which cause the malodorous sewage plant emissions that make these installations
socially unacceptable. Besides, these emissions can contribute to the
corrosion of the instruments, causing a relevant economical in the wastewater
treatment facilities.
Purposes: Develop a photocatalytic treatment system activated by sun light or
UVA lamps that operates under real process conditions.
• Develop an adsorption treatment system that allows retention of the
noxious components of the atmospheres found in wastewater treatment
plants.
• Based on the results of both systems, a new mixed photocatalysisadsorption
system will be developed. This combined reactor should
take advantage of the synergies between both processes, enhancing
the efficiency of each system. The achievement of these goals should
lead to a drastic reduction in the volume of the costly and irritant
chemicals currently used to control these emissions, and consequently
a safer environment for the plant workers will be created.
Achievements in 2006: During this first year of the project, the main effort
focused on the selection of high-efficiency, durable supported photocatalysts.
Different UV-transparent carriers were initially selected and sol-gel-coated
TiO 2 . In parallel, several adsorbents based on high-strength surface materials
(silicates, carbon…) were prepared by extrusion as either plates or monoliths.
Photocatalytic degradation was studied as a function of the flow rate, H 2 S
concentration and humidity. Results show that high conversion of H 2 S can be
achieved with adequate operating conditions. Figure 4.3 illustrates the effect
of humidity on the conversion of some of the photocatalysts assayed. One
significant finding is that following several hours of irradiation, SO 2 can be
detected in the outlet stream, revealing that H 2 S is not only transformed into
sulfate, but can also be oxidized into SO 2 . The selectivity of H 2 S photodegra-
Figure 4.13 Conversion as a function of relative humidity, using glass rings and
polymeric monoliths as TiO 2 catalyst supports.
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