Course on Innovative Processes and Practices for Wastewater Treatment and Re-use
Solar disinfection of drinking water
Dr. Pilar Fernández Ibáñez [email protected] CIEMAT – Plataforma Solar de Almería
-1- Ankara University 8-11 October 2007
Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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1 Water availability
70% of the surface of the Earth has water • 2,5 % freshwater • 1 % human consumption
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Water disinfection needs
Microbial contamination of potable water due to the lack of an appropriate treatment of waste water is now a days a very important problem, especially in regions of developing countries.
Water is the main vehicle of distribution of many waterborne diseases. Water was responsible for big epidemics in the world like tiphus and cholera.
WHO recognised the disinfection as one of the most important barriers for protection of public health.
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2 Access to water in the World in 2025
Everybody might have access to safe water to satisfying main needs of drinking water consume, clean, food production and energy at a reasonable cost. The water suply for these needs has to be done in a sustainable way.
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Water disinfection issue Causes of the problem: • Lack of adecuated systems for water treatment and purification. • Scarcity of rainwater. • Restricted access to water resources due to contamination of hydric resources. • Lack of adequated intallations Percentage of disinfected water for water storage. in rural areas of Latinamerica. • Lack of effective and adequate water distribution systems. •Etc. -6- Ankara University 8-11 October 2007
3 Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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Disinfection of water
Desinfection: killing or inactivation of pathogenic microorganisms.
• Indicators: bacteria total coliforms and faecal coliforms.
• Standard methods: Chlorine Chloramine Ozone UV(C) light
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4 Water Disinfection Disinfection techniques
Physiscal removal Microorganism of microorganisms inactivation (death)
9Coagulation and sedimentation 9Chlorination 99HighOzonation efficiency for virus and bacteria 9Filtering 99WidelyHighlyUV(C) oxidativeused: disinfection 100 years Fast filtering 989ExpensiveTHMGermicidalTechnologies and other effect: carcinogenics 254under nm. research Sand filtering 98 BromateFlavourNo generatesPhotocatalysis to generation water toxic by-products (toxic) Active carbon 8 Non-oxidativeIn-situElectrophotocatalysis generation Membrane filtering 8 Not feasiblePhotosensitation with natural light 8 ExpensiveSolar water disinfection 9 Widely used 8 Expensive 8 Do not really destroy microorganisms EPA (Environmental Protection Agency) Clasification , 1999 -9- Ankara University 8-11 October 2007
Chlorination
Gas chloride, sodium and calcium hypochlorite
Advantages • Highly germicidal • Residual effect • Bacterial re-growth control
Disadvantages • Generation of toxic by-products • Bad odour and taste to water • Dangerous reactivity with NOM
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5 Ozonation
Ozone (from Air or Oxygen)
Advantages • Require low doses and contact times (300-3000 faster than chlorine) • Non-generation of THM, except for the presence of Bromide.
Disadvantages • Non-residual effect • Potentially toxic by-products • In situ generation • Immediately used • Expensive O&M • Technically complex -11- Ankara University 8-11 October 2007
UV-C disinfection UV-C lamps
Advantages •Easy O&M • Non-generation of toxic by-products
Disadvantages • Non-residual effect • Uneffective against protozoan • Limited disinfectant effect by colour, turbidity and suspended matter • Bacterial re-growth if genetic material is not destroyed
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6 UV-C disinfection
Disinfection mechanism with UV-C radiation
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UV-C disinfection
More resistant
Less resistant
Required UV-C dose to reach a 90% of inactivation with different microorganisms (adapted from Bitton, 2005). -14- Ankara University 8-11 October 2007
7 Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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Solar disinfection: SODIS
Solar radiation itself has not germicidal effect. Nevertheless, the synergistic effect of solar (UV-A) radiation and thermal heating of water under solar exposure has an important disinfectant capacity so-called SODIS or “Solar Disinfection”.
5 10 Temperature 60 From 1958104 it is known that solar 50photons with wavelenghts
3 40 between10 300 y 500 nm may inhibitT(ºC) the reproduction capacity 30 102 of a variety of microorganisms. 20 1 total coliforms 10 10 TC [CFU/100mL]
100 0 Photo-repair0 mechanisms 20406080100are also well known in bacteria (no Caslake et al., Appl. Environ. 2 virus) in the sameDose spectral UV-A [J/m range] (1967).Microbiol. 2004, 70, 1145–1150 -16- Ankara University 8-11 October 2007
8 Solar disinfection When inactivation is done under constant irradiation conditions: Disinfection kinetics (also for disinfecting agents like chlorine, UV, etc.) obeys to a first order kinetics, Chick Law:
Nt: concentration of viable microorganisms at time t. K: constant of disinfection rate.
This relationship under solar radiation changes to:
Gill & McLoughlin, Journal of Solar Energy Engineering, ASME, 2007. -17- Ankara University 8-11 October 2007
Solar disinfection Experimental time is used to compare results when lamps are used. When solar radiation drives the process, we can use the following evaluation parameters: a) QUV: cumulative UV energy during exposure time per unit of volume of treated water (J l-1).
b) UV Dose: UV energy received per unit surface during exposure time (J m-2). DoseUV = UVG,n· ∆tn c) UV Energy: total UV energy received during exposure time (J).
EnergyUV = UVG,n·A· ∆tn -18- Ankara University 8-11 October 2007
9 Water Disinfection
WATERBORNE PATHOGENS
VIRUS BACTERIA PROTOZOA HELMINTHS •Poliovirus • Salmonella • Giardia lamblia • Taenia saginata •Hepatitis A •Shigella •Entamoeba •Ascaris •Parvovirus •Campylobacter histolytica lumbricoides •Adenovirus •Vibrio • Crystosporidium •Schistosoma •Rotavirus • Escherichia coli
Inactivation -19- Ankara University 8-11 October 2007
Solar disinfection: SODIS
www.sodis.ch (EAWAG, Switzerland) -20- Ankara University 8-11 October 2007
10 Solar disinfection of E. coli
Viability under Natural solar radiation at PSA 3.5 kJ
McGuigan et al., J. Applied Microbiology 2006, 101, 453-463. -21- Ankara University 8-11 October 2007
Solar disinfection of pathogenic bacteria
E. coli Kehoe et al., Letters in Applied Microbiology 2004, 38, 410–414. -22- Ankara University 8-11 October 2007
11 Solar disinfection of C. Parvum oocysts
Mice Infectivity McGuigan et al., J. Applied Solar simulator: 830 W m-2, 40ºC Microbiology 2006, 101, 453-463. -23- Ankara University 8-11 October 2007
Solar disinfection of Fusarium spores
1000
100 (CFU/mL) (CFU/mL)
F. equiseti 10 F. antophilum F. verticillioides F. solani 1 F. oxysporum Concentration
0 2 4 6 8 101214 Q (kJ/L) UV
Under natural solar radiation C. Sichel, et al. Appl. Cat. B: Wild fungal spores Environ. 74 (2007) 152-160. -24- Ankara University 8-11 October 2007
12 Resistance relative to the solar radiation of several microorganisms versus E. coli
Gill & McLoughlin, Journal of Solar Energy Engineering, ASME, 2007. -25- Ankara University 8-11 October 2007
Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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13 AOPs
Ò AOPs are based on generation of a highlyOxidation oxidative species. Species potential • Ò The AOPs that produce hydroxyl radicalsref. HgCl(2 (V)OH) are the most efficient. Fluorine 2.23 Hydroxyl radical 2.06 Oxygen 1.78 Hydrogen peroxide 1.31 Peroxide radical 1.25 Permanganate 1.24 Hypobromite acid 1.17 Chloride dioxide 1.15 Hypochlorite acid 1.10 Chlorine 1.00 Bromine 0.80 Iodine 0.54 -27- Ankara University 8-11 October 2007
AOPs - ●OH
H O /O /UV H22O22/O33/UV
HH2OO2/O/O3 γγ-rays-rays 2 2 3 ●OH
O /UV Supercritical O33/UV Supercritical WaterWater Oxydation Oxydation UV/TiO /H O UV/TiO22/H22O22 PhotocatalyticalPhotocatalytical processesprocesses
UV/Fe+3+3/H O UV/Fe /H22O22
Solar photocatalysis -28- Ankara University 8-11 October 2007
14 AOPs - ●OH
Terrestrial and extraterrestrial solar spectrum (48.2º zenit angle)
2200
2000 EstraterrestrialEstraterrestrialIrradianciaSolar Irradiance solar irradiance µm) 2 1800
(W/m 1600
1400
1200
1000 O 3 Direct solar irradiance
800 H2O IrradianciaSolar Directa estándar oversobre la the superficieterrestre(ASTM Earth surface O/CO 600 O3 H2O 2 E891-87, para Masade Aire = 1,5) O2 (Air Mass: 1.5)
400 H2 O/CO2 200 O2 Direct Normal Irradiance H2 O 0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 2,8 Wavelength (µm) -29- Ankara University 8-11 October 2007
AOPs - ●OH
Several semiconductors may act as photocatalisyts 9 High UV absorptivity ZnS (3.7 eV) 9 High adsorption rate of many contaminants ZnO (3.2 eV) 9 Redox potential (EBV-EBC) adequate for TiO2 (3.05-3.25 eV) organics oxidation
Fe2O3 (2.2 eV) 9 High photocatalytic activity CdO (2.1 eV), etc. 9 Resistant to photo-corrosion 9 Recyclable (re-usable) 9 Inocuos 9 Easy to handle 9 Low cost and high production -30- Ankara University 8-11 October 2007
15 AOPs - ●OH
Heterogeneous photocatalysis using semiconductor oxides The photoexcitation of semiconductor particles promotes an electron from the valence band to the conduction band thus leaving an electron hole in the valence band; in this way, electron/hole pairs are generated.
EBG (TiO2) = 3.05-3.25 eV Photon: E = h·ν h·ν > EBG λ < 300-390 nm (5-7% Solar spectrum)
hν − + TiO2 ⎯⎯→ TiO2( e + h ) e–/h+ recombination ⇔ e–/h+ separation + • + h + H 2O→ OH + H − •− e + O2 → O2 -31- Ankara University 8-11 October 2007
AOPs - ●OH
h·ν≥3.2 eV h·υ Recombination TiO2 e-/h+
- + eBC hBV Red1 Oxid2 O 2 - e Oxid1 Red2 -• O2 h+
• + H2O OH + H Recombination AQUEOUS PHASE Photo-oxidation
+ − h + Re d2,ads → Ox2,ads e + Ox1,ads → Red1,ads
Before catalyst phoytoexcitation, Red2 and Ox1 species have to be previously adsorbed on the catalyst surface to avoid recombinations of e-/h+ pais. -32- Ankara University 8-11 October 2007
16 TiO2-UV disinfection
The first contribution on water disinfection using TiO2 assisted photocatalysis was done by Matsunaga in 1985. Up to now:
- Electrophotocatalyisis and photocatalysis with TiO2 - supported and slurry TiO 20 Scientific publications on 2 TiO photocatalytic 2 -Lampsand solar radiation water disinfection 15
1.0
Fotocatalysis-P25 10 0.8 Without catalyst
0.6 5 C =1000 CFU/mL 0 1mg/mL TiO 0.4 2 Lamp: 320-420 nm publications journals Indexed Ratio Viable Cell 0 0.2 1980 1985 1990 1995 2000 2005
0.0 Year 0 10203040506070 M. Bekbölet, Water Science & Irradiation time, min Technology 35 (1997) 95-100. -33- Ankara University 8-11 October 2007
TiO2-UV disinfection
BACTERIA: Enterococcus faecalis (Gram+) Escherichia coli (Gram-)
1 µm 1 µm
VIRUS AND BACTERIOPHAGE: Poliovirus 1, Phage MS2 (RNA- bacteriophage)
CANCER CELLS: HeLa cells (cervical carcinoma), T24 (bladder cancer), U937 (leukemia). FUNGI AND YEATS:
Saccharomyces Conidia Cerevisiae Neurospora crassa
“Advanced Oxidation Processes for Water and Wastewater Treatment” IWA Publishing, 2004. D.M. Blake et al., Separation and Purification Methods, 28 (1999)-34- 1-50. Ankara University 8-11 October 2007
17 Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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Fundamental parameters Irradiation Continuously irradiation has a higher efficiency than intermitent
exposure (TiO2 P25 1g/l). 1.E+08
1.E+07 30 minutes of interrumped illumination 1.E+06
1.E+05
1.E+04
1.E+03
1.E+02
Bacterial survival (CFU/ml) survival Bacterial 30 minutes of 1.E+01 continuous irradiation
1.E+00 0 102030405060708090100 Time (min) Rincón, A.G and Pulgarin C. Appl. Catal. B: Environ. 44 (2003), 263 -36- Ankara University 8-11 October 2007
18 Fundamental parameters Concentration of catalyst Initial inactivation rate increases with the catalyst concentration until it reaches a certain value, due to the light screening efect.
1.E+08 400W/m2 1.E+07 0.25 g/l 0.5 g/l 1.E+06 0.75 g/l 1.E+05 1g/l 1.E+04 1.5 g/l The light screening 1.E+03 effect depends on 1.E+02 the intensity of 1.E+01 radiation and on Bacterial survival CFU/ml survival Bacterial 1.E+00 0 20406080100the initial bacteria Time (min) concentration.
Rincón, A.G and Pulgarin C. Appl. Catal. B: Environ. 44 (2003), 263 -37- Ankara University 8-11 October 2007
Fundamental parameters Post-irradiation events 30 min. exposure to solar simulator radiation: certain inactivaton and a later bacterial regrowth in the dark was observed. The post-irradiation effect depends on light intensity.
1.E+09 dark
1.E+08
1.E+07 400 W/m2
1.E+06
Bacterial survival CFU/ml survival Bacterial 1.E+05 1000 W/m2
1.E+04 0 60 120 180 240 300 360 420 480 540 6001600 660 720 780 3600 Total time (min)
Rincón & Pulgarín, Applied Catalysis B: Environmental 49 (2004) 99–112 -38- Ankara University 8-11 October 2007
19 Fundamental parameters Post-irradiation events The post-radiation effect after photocatalytic treatment provokes a bacterial abatement in the dark.This effect is directly influenced by the radiation intensity.
1.E+09 dark 1.E+08
1.E+07 2 1.E+06 400 Wm
1.E+05
1.E+04
1.E+03
1.E+02 Bacterial survival CFU/ml 1.E+01 1000 W/m2 1.E+00 0 40 80 120 160 200 240 280 320 360 4001600 440 480 520 560 3600 600 Total time (min)
Rincón & Pulgarín, Applied Catalysis B: Environmental 49 (2004) 99–112 -39- Ankara University 8-11 October 2007
Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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20 Disinfection mechanisms Effects of biocidal agents on cells
External e cid cell wall Bio
Inactivation (cidal effect)
Inhibition DNA Cytoplasmatic membrane Structural Enzymes proteins
“Wastewater microbiology”. Gabriel Bitton, John Wiley & Sons, New Jersey, 3rd Ed., 2005. -41- Ankara University 8-11 October 2007
Disinfection mechanisms Bacterial inactivation under solar radiation
Indirect action
UV Photocatalytic effect Direct action of TiO2 attacks the cell membrane. UV absorption by TiO DNA molecules of 2 Decrease of H OÆÆ•OH microorganisms 2 Coenzyme-A levels by photo-oxidation, which induces celular death.
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21 Disinfection mechanisms
Photocatalytic inactivation -• O2
Adsorbed OH• TiO2
Solar UV M S I OH• N A G + R h O O R - + C e /h I M Very small - particles TiO e 2 of TiO2 -• O2 suspended TiO2 40 nm 300 nm >1µm
TiO2 TiO2-aggregates cells
Malato, Fernandez-Ibáñez y Blanco, J. Solar Energy Engineering 129 (2006) 1-12. -43- Ankara University 8-11 October 2007
Disinfection mechanisms
AFM image of E. coli cells on a TiO2 film Light intensity: 1.0 mW/cm2 Without radiation 6 days of exposure
Cylindrical shape Complete cell Size ∼ 1–2.5 µ m decomposition
K. Sunada et al. J. Photochemistry and Photobiology A: Chemistry 6221 (2003) 1–7 -44- Ankara University 8-11 October 2007
22 Disinfection mechanisms
Scheme of photo-destruction (TiO2) process
1) Partial destruction of 2) Reactive species 3) Reactive species external cell wall: partial reach the cytoplasmatic attack the lipidic viability lost. membrane. membrane: cell death.
K. Sunada et al. J. Photochemistry and Photobiology A: Chemistry 6221 (2003) 1–7 -45- Ankara University 8-11 October 2007
Adsorption of TiO2 on E. coli cells
TiO2-aggregate in contact with E. coli
• D. Gumy et al. Appl. Cat. B: Environ., 63 (2006) 76-84. • J. Kiwi and V. Nadtochenko, Composition of cell membrane Langmuir 2005, 21, 4631-4641. favours contact with the catalyst. -46- Ankara University 8-11 October 2007
23 Adsorption of TiO2 on Fusarium spores
TiO2-aggregates in contact with F. equiseti
TiO2 Macroconidia of F. Equiseti before and C. Sichel, et al. Appl. Cat. B: after the photocatalytic treatment (5h) Environ., 74 (2007) 152-160. -47- Ankara University 8-11 October 2007
Adsorption of TiO2 on Fusarium spores
TiO2-aggregates in contact with F. solani
TiO Chlamydospores de F. solani before and 2 after 6h of photocatalytic treatment. C. Sichel, Phytopathology, submitted, 2007. -48- Ankara University 8-11 October 2007
24 Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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Lab Photo-reactor
-Lamp(UV/VIS) - IR filter -Photo-reactor - Refrigeration -Matraz -Sensors -Pump pH T
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25 Requirements for solar photocatalytic reactors
ÒChemical resistance to water, pH, without reagents changing. ÒFlow guaranteed at minimal pressure and maximal homogeneisation. ÒEfficient distribution of UV radiation from the solar collector to the fluid media. ÒResistance to temperatures lightly high: 40-50ºC. ÒRobust and resistant to environmental condictions. ÒEasy handling, low cost operation and maintenance (modular systems). ÒCheap and accesible. -51- Ankara University 8-11 October 2007
Development of solar collectors Compound Parabolic Collectors (CPC) After middle 90s the “Compound Parabolic Collector” or CPC was technologically developed.
CPC concentrates all the incoming radiation within an acceptance angle (2θa) over the recector (fluid), which leads to a Concentration
Factor of 1 when θa = 90º.
The CPC recovers all the UV radiation (direct and diffusse) received in the aperture area of the solar collector.
Partial view of Solar Chemistry facilities at PSA, Almería (CIEMAT)
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26 Experiences at pilot plant
Prototype of solar reactor
- Solar radiation - Photo-reactor (solar collector) -Tank s -Air -Sensor -Pump - Additives -Catalyst
Isometric scheme SOLARDETOX project, Brite Euram, European Commission (1997-2000) -53- Ankara University 8-11 October 2007
Experiences at pilot plant
SOLWATER project, INCO Programme, European Commission (2002-2005)
1 75 cm ,5 ric ct le E x Bo
Tank ,5 90 cm F 50 cm P 100 cm P: pump F: Flowmeter T: Termocouple
30 cm
Compact module of solar photo-reactor
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27 Optical development of CPC for disinfection
Application of Compound Parabolic Collectors (CPC) using new geometries for several configuration of the catalyst (AO SOL, Portugal).
50 mm 50 mm
Cylindrical Support in a CPC Flat support with a special geometry reactor (Ahlstrom paper) (patent pending) solar collector
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Contents
1. Introduction 2. Standard disinfection processes 3. Solar disinfection
4. Water disinfection with TiO2/UV 5. Fundamental parameters 6. Disinfection mechanisms 7. Solar reactors 8. Experiences on disinfection at PSA
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28 Protocol for solar experiments
1. Catalyst preparation. 2. Solar collector covering. 3. Inoculation of culture & recirculation.
4. TiO2 adding dispersed in small volume. 5. Remove the cover. 6. Experiment starting. 7. Average solar UV energy per unit of time and surface -2 (WUV·m ) incoming the photo-reactor.
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Irradiated collector surface Solar Disinfection of E. coli in a CPC reactor
104 Q (60min) = 0 kJ/L UV
QUV(60min) = 0.8 kJ/L 3 Q (60min) = 2.2 kJ/L 10 UV
QUV(60min) = 3.3 kJ/L 2 Q (60min) = 6.5 kJ/L 0.125 m UV 102 0.25 m2
2 101 0.50 m
2
Concentration (CFU/mL) Concentration 0.75 m 100
0 20 40 60 80 100 120 140 Time, min
Fernández-Ibáñez et al. Catalysis Today, 101 (2005) 345-352. -58- Ankara University 8-11 October 2007
29 Catalyst disposal
Disinfection with TiO2 of E. coli in a solar CPC reactor
100000
No catalyst 10000
Fixed TiO (19,3 g/m2) 1000 2
Fixed TiO reused 2
C, CFU/mL 100 Slurry TiO (50 mg/L) 2
10 012345 Q , kJ/L UV
Fernández-Ibáñez et al. Catalysis Today, 101 (2005) 345-352. -59- Ankara University 8-11 October 2007
Reactor flow rate
Disinfection of E. coli with immobilised TiO2 in a CPC reactor 8 GinaFit model 2Lmin 5Lmin 6 10Lmin
4
Log (concentration) 2 Experimental data 2L/min 5L/min 10L/min 0 01234
Q UV (kJ/L) C. Sichel, et al. J. Photochem. Photobiol. A, 189 (2007) 239-246. -60- Ankara University 8-11 October 2007
30 Matrix of the water
Solar disinfection of E. coli in a CPC reactor
106
Real (well) water 5 10 + solar radiation (CPC) reactor1 104 reactor2
3 10
102 survival (CFU/mL) survival
101 Distilled water E.coli E.coli + solar radiation (CPC) 100 2L/min 10 L/min 0 2 4 6 8 101214 Q (kJ/L) UV Solar disinfection for real water is slower and less efficient than for distilled water. This graph shows the “tailing effect” attributed to resistant colonies of bacteria. -61- Ankara University 8-11 October 2007
Weather conditions
Solar disinfection of F. antophilum with slurry TiO2 Sunny day (March 22nd 2006) solar-only Hourly average UV irradiance 4 sunlight+TiO Cumulative UV dose 10 2 1000 50 SUNNY DAY )
-1 3 800 40
10 ) ) 2 -
2 Max. UV Irradiance: - 42 Wm-2
600 30 W m ( 2 kJ m (
(CFU mL 10 Max. UV Dose: 400 20 750 kJm-2 101 UV Dose
200 10 F. antophilum F. UV Irradiance UV 100 0 0 10:00 11:00 12:00 13:00 14:00 15:00 Local Time C. Sichel, et al. Catalysis Today 2007, in press. -62- Ankara University 8-11 October 2007
31 Weather conditions
Solar disinfection of F. antophilum with slurry TiO2 Cloudy day (March 21st 2006) solar-only Hourly average UV irradiance 4 sunlight+TiO Cumulative UV dose 10 2 1000 50 CLOUDY DAY ) -1 3 800 40 ) 2
10 - ) 2
- Max. UV Irradiance: W m 600 30 ( -2 2 25 Wm kJ m
(CFU mL 10 (
400 20 Max. UV Dose: 101 380 kJm-2 UV Dose UV
200 10 UV Irradiance F. antophilum 100 0 0 10:00 11:00 12:00 13:00 14:00 15:00 Local Time
Similar photocatalytic kinetics for both cases. C. Sichel, et al. Catalysis Solar disinfection yields very different results. Today 2007, in press. -63- Ankara University 8-11 October 2007
Weather conditions
Disinfection of E. coli with immobilised TiO2 Spring & Summer seasons Initial concentration SPRING AND SUMMER
) 50 -2 Final concentration -2 Max.~ 45 W m -2 6 (UVmax:38-45wm ). 10 40
5 30
) 10 Spring and summer -1 20 th May 8 2004 nd 4 July 2 2004 10 10 April 20th 2005 September 30th 2005
Solar UV irradiance (W m 0 3 10:00 12:00 14:00 16:00 18:00 20:00
(CFU mL 10 Local time
102 E. coli Detection 101 limit
4.63 5.72 9.85 10.79 13.12 Q (kJ L-1) C. Sichel, et al. Catalysis UV Today 2007, in press. -64- Ankara University 8-11 October 2007
32 Weather conditions
Disinfection of E. coli with immobilised TiO2 Autumn &Winter seasons Initial concentration AUTUM AND WINTER 6 -2 10 Final concentration ) 50 -2 (UVmax: 28-38Wm ). -2 40 Max.~ 38 W m 5
) 10 30 -1
4 20 10 Autumn and winter October 27th 2004 10 January 30th 2004 th 3 February 11 2005 November 28th 2005
10 m (W irradiance UV Solar 0 (CFU mL (CFU 10:00 12:00 14:00 16:00 18:00 20:00 Local time 102 E. coli
1 10 Detection limit
3.33 3.47 3.83 3.95 4.04 Q (kJ L-1) C. Sichel, et al. Catalysis UV Today 2007, in press. -65- Ankara University 8-11 October 2007
Role of solar radiation
Comparison of experiments in different seasons, early and later in the day, and under cloudy and sunny conditions, leads us to conclude that solar photocatalytic disinfection does not depend proportionally on solar UV irradiance (solar UV intensity) as long as enough photons have been received for disinfection.
The minimum UV energy necessary to reach a certain disinfection depends on the microorganism and the reactor configuration.
Solar-only disinfection requires higher minimum solar UV irradiance and higher minimum UV dose for disinfection than solar photocatalytic disinfection. -66- Ankara University 8-11 October 2007
33 Inactivation of C. parvum
Sodis and solar photocatalysis with fixed TiO2
100 ) -2 1000 SODIS Real Sunlight SPCDIS Real Sunlight 80 750 Control
60 500
250 40 Global Irradiance (Wm DAY 1 DAY 2 DAY 3 Viability (%) 0 0 4 8 12 16 20 24 20 Cumulative Exposure Time (h)
C. parvum oocysts 0 0 102030405060 Cumulative Global Exposure (MJ m-2)
F. Mendez-Hermida, et al. J. Photochem. Photobiol. A, 88 (2007) 105-111. -67- Ankara University 8-11 October 2007
Photocatalytic inactivation Fusarium
F. equiseti 1000 F. antophilum F. verticillioides F. solani F. oxysporum 100 (CFU/mL)
10 Concentration
1
02468101214 Q (kJ/L) UV C. Sichel, et al. Appl. Cat. B: Environ., 74 (2007) 152-160. -68- Ankara University 8-11 October 2007
34 Applications
The AQUACAT and SOLWATER projects were financed by EU under the INCO-DEV program during (2003-2006)
MAIN OBJECTIVE: development of a completely autonomous solar system chemical-free for drinking water disinfection and, additionally, elimination of potential organic pollutants at trace level.
SOLWATER prototype at PSA Fixed catalyst Ahlstrom patent, 1999 France -69- Ankara University 8-11 October 2007
Applications
Design of the final system for disinfection of drinking water
1 5 1.PV panel 2.& 3. Solar
3 4 Photo-reactor 4. Pump 5. Electric box 6. Connections
2 6
S. Malato et al., Review, Catalysis Today 122 (2007) 137-149. -70- Ankara University 8-11 October 2007
35 Applications
Final reactor systems in South-America and North-Africa
ESTF. Fez, MOROCCO Photo Energy Center. Cairo, EGYPT
IMTA. Morelos, MEXICO. CNEA. Tucumán, ARGENTINA -71- Ankara University 8-11 October 2007
Applications SODISWATER project Solar Disinfection of Drinking Water for Use in Developing Countries or in Emergency Situations
Partners: Objetive: 1. RCSI (IRELAND) The objective of this project is the development 2. UU (UK) of an implementation strategy for the 3. CSIR (SOUTH AFRICA) adoption of solar disinfection of drinking 4. EAWAG (SWITZERLAND) water as an appropriate, effective and 5. IWSD (ZIMBABWE) acceptable intervention against waterborne 6. CIEMAT (SPAIN) disease for vulnerable communities in 7. UL (UK) developing countries without reliable access to 8. ICROSS (KENYA) safe water, or in the immediate aftermath of 9. USC (SPAIN) natural or man-made disasters.
The main activity of PSA within this project is the development of a solar reactor to enhance the disinfection results of “batch” SODIS processes. -72- Ankara University 8-11 October 2007
36 Applications
FITOSOL project Elimination of phytopathogens in water through photocatalytic processes: application for the water disinfection and reuse in recirculation hydroponic cultures
Main objetives:
• Study at laboratory scale of solar photocatalytic elimination of model phytopathogenic microorganisms in recirculation liquid nutrient solutions in soil-less cultures.
• Design and construction of a pilot solar reactor for disinfection of water containing the mentioned phytopathogenic organisms to reuse in recirculation hydroponic cultures.
• Demonstration of the photocatalytic process ability to disinfect water from nutrient solutions of hydroponic cultures. -73- Ankara University 8-11 October 2007
Future
1. Low-cost solutions for drinking water suply at house-hold level.
2. Use of AOPs (different to TiO2) for water disinfection.
3. Improve the knowledge on the disinfection mechanisms at microbiological level.
4. Investigate the effects of the disinfection treatment using infectifivity tests for pathogenic microorganisms.
5. Field trials of solar disinfection to better Health Impact Assessment of the technology. -74- Ankara University 8-11 October 2007
37 Acknowledgements
This work has been financed by:
European Commission under the SOLWATER project ICA4-CT-2002-10001.
European Commission under the AQUACAT INCO project, ICA3-CT2002-10016.
European Commission under the SODISWATER project, contract FP6-2004-INCO-DEV-3-301650.
Spanish Ministerio de Educación y Ciencia under the FITOSOL project, AGL2006-12791-C02. -75- Ankara University 8-11 October 2007
THANKS
Dr. Pilar Fernández Ibáñez [email protected]
Plataforma Solar de Almería –CIEMAT Ministerio de Educación y Ciencia www.psa.es
-76- Ankara University 8-11 October 2007
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