Annual Report 2006 - Plataforma Solar de Almería

ENVIRONMENTAL APPLICATIONS OF SOLAR ENERGY
Figure 4.7
Degradation of Fusarium equiseti spores (left) and Fusarium verticillioides (right)
by solar irradiation and solar photocatalysis with TiO 2 in suspension (35 mg/L)
under natural solar radiation at the Plataforma Solar de Almería (right [4.5]).
conventional chemical disinfectants (toxic and nonbiodegradable compounds)
which contribute a certain level of undesirable toxicity to the nutritive water
solution. Photocatalytic treatment Effectiveness of the photocatalytic treatment
will be evaluated using models present in horticultural crops in the
Spanish Southeast: Pythium aphanidermatum, the cause of root rot and hypocotyl
rot, which leads to wilting in cucurbits, Phytophthora parasitica, which
causes root rot and tomato end rot, Fusarium oxysporum f.sp. radiciscucumerinum,
fungi excluding zoosporangium (water mold), which causes
significant losses wherever it appears and Olpidium bornovanus, vector of the
melon necrotic spot virus (MNSV) on melon and watermelon plants. Experimental
confirmation of capacity for photocatalytic disinfection of these pathogens
will be done in the laboratory and at pilot scale, in the solar reactors at
the Plataforma Solar de Almería facilities. Finally, the results will be tested in
a crop in non-recirculating systems typical at the University of Almería experimental
facilities.
Purposes:
• Laboratory study of elimination of model phytopathogenic microorganisms
in crops in non-recirculating nutritive solution by solar photocatalysis
with TiO 2 (in suspension and supported) and with photo-Fenton.
• Design and construction of a pilot solar reactor for disinfection of water
with the above-mentioned phytopathogenic microorganisms for application
in the reuse of water used in recirculating hydroponic cultures.
• Evaluation of the results of treatment of phytopathogens in water from
photocatalysis using model phytopathogens from different types of
crops normally grown without soil.
• Demonstration of the feasibility of photocatalysis for disinfection of
polluted water from nutritive solutions in hydroponic cultures will be
carried out in the laboratory and at pilot scale in the solar reactors at
the facilities of the Plataforma Solar de Almería. Finally, the results will
be tested in a recirculating hydroponic crop typical of the University of
Almería’s experimental facilities.
Objectives achieved in 2006: The first experiments on solar photocatalytic
degradation with TiO 2 and solar inactivation without catalyst were carried out
at the PSA with Fusarium equiseti spores. “Batch” reactors are used for this
without concentration with natural solar irradiation times of 6 hours on perfectly
clear days. The results show an important effect of the solar radiation
on the viability of the F. equiseti spores. The use of titanium dioxide (P25) as
a catalyst shows a noticeable improvement in disinfection efficiency (Figure
81