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
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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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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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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: 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.
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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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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 -8Ankara University 8-11 October 2007
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Water Disinfection Disinfection techniques Physiscal removal of microorganisms
Microorganism inactivation (death)
9Coagulation and sedimentation 9Filtering Fast filtering Sand filtering Active carbon Membrane filtering
9Chlorination 99Ozonation High efficiency for virus and bacteria disinfection Widely used: 100 years 99UV(C) Highly oxidative under THM and other carcinogenics 8 9Technologies Expensive 9 Germicidal effect: 254 nm.research Flavour togeneration water 8 Bromate (toxic) Photocatalysis 9 No generates toxic by-products In-situ generation 8 Non-oxidative Electrophotocatalysis 8 Not feasible with natural light Photosensitation 8 Expensive Solar water disinfection
9 Widely used 8 Expensive 8 Do not really destroy microorganisms EPA (Environmental Protection Agency) Clasification , 1999
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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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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
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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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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).
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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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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”. 10
5
Temperature 60
4
TC [CFU/100mL]
10 From 1958 it is known that solar 50photons with wavelenghts 40 T(ºC) the reproduction capacity between10300 y 500 nm may inhibit 30 10 of a variety of microorganisms. 20 3
2
10
1
total coliforms
10
0
0 Photo-repair mechanisms also well Caslake known in bacteria (no 0 20 40 60 80are 100 et al., Appl. Environ. Dose UV-A [J/m ] Microbiol. 2004, 70, 1145–1150 virus) in the same spectral range (1967). -1610
2
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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.
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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
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Water Disinfection
WATERBORNE PATHOGENS VIRUS • Poliovirus • Hepatitis A • Parvovirus • Adenovirus • Rotavirus
BACTERIA • Salmonella • Shigella • Campylobacter • Vibrio • Escherichia coli
PROTOZOA • Giardia lamblia • Entamoeba histolytica • Crystosporidium
HELMINTHS • Taenia saginata • Ascaris lumbricoides • Schistosoma
Inactivation -19Ankara University 8-11 October 2007
Solar disinfection: SODIS
www.sodis.ch (EAWAG, Switzerland)
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Solar disinfection of E. coli Viability under Natural solar radiation at PSA =48 W 20ºC
3.5 kJ
m-2
McGuigan et al., J. Applied Microbiology 2006, 101, 453-463.
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Solar disinfection of pathogenic bacteria
E. coli Kehoe et al., Letters in Applied Microbiology 2004, 38, 410–414.
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Solar disinfection of C. Parvum oocysts
Mice Infectivity Solar simulator: 830 W m-2, 40ºC
McGuigan et al., J. Applied Microbiology 2006, 101, 453-463.
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Concentration (CFU/mL)
Solar disinfection of Fusarium spores
1000
100
F. equiseti F. antophilum F. verticillioides F. solani F. oxysporum
10
1
0
2
4
6
8
10
12
14
QUV (kJ/L) Under natural solar radiation Wild fungal spores
C. Sichel, et al. Appl. Cat. B: Environ. 74 (2007) 152-160.
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Resistance relative to the solar radiation of several microorganisms versus E. coli
Gill & McLoughlin, Journal of Solar Energy Engineering, ASME, 2007.
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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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AOPs Oxidation Ò AOPs are based on generation of a highly oxidative species. Species
potential
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
ref. HgCl(2•(V) Ò The AOPs that produce hydroxyl radicals OH) are the most Fluorine 2.23 efficient.
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AOPs - ●OH HH2OO2/O 33/UV /UV 2 2/O HH2OO2/O 33 2 2/O OO3/UV 3/UV
γ-rays γ-rays
●OH
Supercritical Supercritical Water WaterOxydation Oxydation
UV/TiO UV/TiO22/H /H22OO22
Photocatalytical Photocatalytical processes processes +3 UV/Fe UV/Fe+3/H /H22OO22
Solar photocatalysis
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AOPs - ●OH Terrestrial and extraterrestrial solar spectrum (48.2º zenit angle) 2 Direct Normal Irradiance (W/m µm)
2200
IrradianciaSolar Estraterrestrial Irradiance Estraterrestrial solar irradiance
2000 1800 1600 1400 1200 1000
O3
800
H2 O O3
600
O2
H2 O
O/CO2
Direct solar irradiance IrradianciaSolar Directa estándar over the Earth surface sobre la superficieterrestre(ASTM E891-87, para Masade (Air Mass: 1.5) Aire = 1,5)
400 H2 O/CO2
200
O2
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)
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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) TiO2 (3.05(3.05-3.25 eV)
9 Redox potential (EBV-EBC) adequate for 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
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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 O →• OH + H + 2
e − + O2 → O2•−
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AOPs - ●OH h·ν ≥ 3.2 eV h·υ Recombination
TiO2 e-/h+ eBC- hBV+ O2
e
-
O2-•
Red1
Oxid2
Oxid1
Red2
+
h H2O
AQUEOUS PHASE
•
OH + H+ Recombination
Photo-oxidation
h + + Re d 2 ,ads → Ox2 ,ads
e − + Ox1,ads → Re d1,ads
Before catalyst phoytoexcitation, Red2 and Ox1 species have to be previously adsorbed on the catalyst surface to avoid recombinations of e-/h+ pais.
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TiO2-UV disinfection
Indexed journals publications
The first contribution on water disinfection using TiO2 assisted photocatalysis was done by Matsunaga in 1985. Up to now: - Electrophotocatalyisis and photocatalysis with TiO2 20 Scientific publications on - supported and slurry TiO2 TiO photocatalytic water disinfection - Lamps and solar radiation 1.0 Fotocatalysis-P25 Without catalyst
Ratio Viable Cell
0.8
0.6 C0=1000 CFU/mL 1mg/mL TiO2
0.4
Lamp: 320-420 nm
2
15
10
5
0
0.2
1980 0.0
1985
1990
1995
2000
2005
Year 0
10
20
30
40
50
60
70
M. Bekbölet, Water Science & Technology 35 (1997) 95-100.
Irradiation time, min
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TiO2-UV disinfection BACTERIA: Enterococcus faecalis (Gram+)
Escherichia coli (Gram-)
1 µm
1 µm
VIRUS AND BACTERIOPHAGE: Poliovirus 1, Phage MS2 (RNAbacteriophage)
CANCER CELLS: HeLa cells (cervical carcinoma), T24 (bladder cancer), U937 (leukemia).
FUNGI AND YEATS:
Saccharomyces Cerevisiae
Conidia Neurospora crassa
“Advanced Oxidation Processes for Water and Wastewater Treatment” IWA Publishing, 2004. D.M. Blake et al., Separation and Purification Methods, 28 (1999) 1-50.
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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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Fundamental parameters Irradiation Continuously irradiation has a higher efficiency than intermitent exposure (TiO2 P25 1g/l). Bacterial survival (CFU/ml)
1.E+08 30 minutes of interrumped illumination
1.E+07 1.E+06 1.E+05 1.E+04 1.E+03 1.E+02
30 minutes of continuous irradiation
1.E+01 1.E+00 0
10
20
30
40
50
60
70
80
90
100
Time (min) Rincón, A.G and Pulgarin C. Appl. Catal. B: Environ. 44 (2003), 263
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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. Bacterial survival CFU/ml
1.E+08
400W/m2
1.E+07
0.25 g/l 0.5 g/l 0.75 g/l 1g/l 1.5 g/l
1.E+06 1.E+05 1.E+04 1.E+03 1.E+02 1.E+01 1.E+00 0
20
40
60
80
100
Time (min)
The light screening effect depends on the intensity of radiation and on the initial bacteria concentration.
Rincón, A.G and Pulgarin C. Appl. Catal. B: Environ. 44 (2003), 263
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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.
Bacterial survival CFU/ml
1.E+09
dark
1.E+08
1.E+07
2
400 W/m
1.E+06
1.E+05 2
1000 W/m 1.E+04 0
60
120
180
240
300
360
420
480
Total time (min)
540
1600 660 600
720
3600 780
Rincón & Pulgarín, Applied Catalysis B: Environmental 49 (2004) 99–112
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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
Bacterial survival CFU/ml
1.E+07 400 Wm2
1.E+06 1.E+05 1.E+04 1.E+03 1.E+02
2 1000 W/m
1.E+01 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
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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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Disinfection mechanisms Effects of biocidal agents on cells e cid Bio
External cell wall
Inactivation (cidal effect)
Inhibition DNA
Cytoplasmatic membrane Enzymes
Structural proteins “Wastewater microbiology”. Gabriel Bitton, John Wiley & Sons, New Jersey, 3rd Ed., 2005.
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Disinfection mechanisms Bacterial inactivation under solar radiation Indirect action Direct action
UV
UV absorption by DNA molecules of microorganisms
Photocatalytic effect of TiO2 attacks the cell membrane. TiO2 H2OÆ Æ •OH
Decrease of Coenzyme-A levels by photo-oxidation, which induces celular death.
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Disinfection mechanisms Photocatalytic inactivation
O2-• Adsorbed TiO2
OH• IS M
Solar UV G
A N
OH• M IC R
O
O R
h+
e-/h+ e-
TiO2
O2-•
Very small particles of TiO2
suspended TiO2
40 nm
300 nm
>1µm
TiO2-aggregates
TiO2
cells
Malato, Fernandez-Ibáñez y Blanco, J. Solar Energy Engineering 129 (2006) 1-12.
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Disinfection mechanisms AFM image of E. coli cells on a TiO2 film Light intensity: 1.0 mW/cm2
Without radiation
Cylindrical shape Size ∼ 1–2.5 µ m
6 days of exposure
Complete cell decomposition
K. Sunada et al. J. Photochemistry and Photobiology A: Chemistry 6221 (2003) 1–7
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Disinfection mechanisms Scheme of photo-destruction (TiO2) process
1) Partial destruction of external cell wall: partial viability lost.
2) Reactive species reach the cytoplasmatic membrane.
3) Reactive species attack the lipidic membrane: cell death.
K. Sunada et al. J. Photochemistry and Photobiology A: Chemistry 6221 (2003) 1–7
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Adsorption of TiO2 on E. coli cells TiO2-aggregate in contact with E. coli
Composition of cell membrane favours contact with the catalyst.
• D. Gumy et al. Appl. Cat. B: Environ., 63 (2006) 76-84. • J. Kiwi and V. Nadtochenko, Langmuir 2005, 21, 4631-4641.
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Adsorption of TiO2 on Fusarium spores TiO2-aggregates in contact with F. equiseti
TiO2 Macroconidia of F. Equiseti before and after the photocatalytic treatment (5h)
C. Sichel, et al. Appl. Cat. B: Environ., 74 (2007) 152-160.
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Adsorption of TiO2 on Fusarium spores TiO2-aggregates in contact with F. solani
Chlamydospores de F. solani before and after 6h of photocatalytic treatment.
TiO2 C. Sichel, Phytopathology, submitted, 2007.
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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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Lab Photo-reactor
-
Lamp (UV/VIS) IR filter Photo-reactor Refrigeration Matraz Sensors Pump pH T
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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.
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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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Experiences at pilot plant Prototype of solar reactor - Solar radiation - Photo-reactor (solar collector) - Tank - Air - Sensor - Pump - Additives - Catalyst
s
Isometric scheme SOLARDETOX project, Brite Euram, European Commission (1997-2000) Ankara University 8-11 October 2007
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Experiences at pilot plant SOLWATER project, INCO Programme, European Commission (2002-2005)
17 c m 5 ,5
ic ct r E le 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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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
Cylindrical Support in a CPC reactor (Ahlstrom paper)
50 mm
Flat support with a special geometry (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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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 (WUV·m-2) incoming the photo-reactor.
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Irradiated collector surface Solar Disinfection of E. coli in a CPC reactor
Concentration (CFU/mL)
10
4
Q UV(60min) = 0 kJ/L Q UV(60min) = 0.8 kJ/L 10
3
Q UV(60min) = 2.2 kJ/L Q UV(60min) = 3.3 kJ/L
10
0.125 m
2
0.25 m 10
1
10
0
0.50 m 0.75 m
0
20
40
2
Q UV(60min) = 6.5 kJ/L
2
2
2
60
80
100
120
140
Time, min Fernández-Ibáñez et al. Catalysis Today, 101 (2005) 345-352.
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Catalyst disposal Disinfection with TiO2 of E. coli in a solar CPC reactor 100000
No catalyst
C, CFU/mL
10000
2
Fixed TiO 2 (19,3 g/m )
1000
Fixed TiO 2 reused 100
Slurry TiO 2 (50 mg/L) 10 0
1
2
3
4
5
Q UV, kJ/L Fernández-Ibáñez et al. Catalysis Today, 101 (2005) 345-352.
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Reactor flow rate Disinfection of E. coli with immobilised TiO2 in a CPC reactor 8 GinaFit model 2Lmin 5Lmin 10Lmin
Log (concentration)
6
4
2
Experimental data 2L/min 5L/min 10L/min
0 0
1
2
3
4
Q UV (kJ/L) C. Sichel, et al. J. Photochem. Photobiol. A, 189 (2007) 239-246.
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Matrix of the water Solar disinfection of E. coli in a CPC reactor 6
E.coli survival (CFU/mL)
10
Real (well) water
5
10
+ solar radiation (CPC)
reactor1 reactor2
4
10
3
10
2
10
1
10
Distilled water + solar radiation (CPC) 2L/min 10 L/min
0
10
0
2
4
6
8
10
12
14
QUV (kJ/L)
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 -61bacteria. Ankara University 8-11 October 2007
Weather conditions Solar disinfection of F. antophilum with slurry TiO2 nd
4
10
Sunny day (March 22 2006) solar-only sunlight+TiO2
Hourly average UV irradiance Cumulative UV dose 1000
50
40
600
30
400
20
200
10
0
0
2
10
1
10
UV Irradiance (W m-2)
800
3
10
UV Dose (kJ m-2)
-1
F. antophilum (CFU mL )
SUNNY DAY Max. UV Irradiance: 42 Wm-2 Max. UV Dose: 750 kJm-2
0
10
10:00
11:00
12:00
13:00
14:00
Local Time
15:00
C. Sichel, et al. Catalysis Today 2007, in press.
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Weather conditions Solar disinfection of F. antophilum with slurry TiO2 st
Cloudy day (March 21 2006) solar-only sunlight+TiO2
4
Hourly average UV irradiance Cumulative UV dose
1000
50
800
40
600 2
10
400 1
10
UV Irradiance (W m-2)
3
10
UV Dose (kJ m-2)
CLOUDY DAY
-1
F. antophilum (CFU mL )
10
Max. UV Irradiance: 25 Wm-2
30
Max. UV Dose: 380 kJm-2
20
200
10
0
0
0
10
10:00
11:00
12:00
13:00
14:00
15:00
Local Time
Similar photocatalytic kinetics for both cases. Solar disinfection yields very different results.
C. Sichel, et al. Catalysis Today 2007, in press.
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Weather conditions Disinfection of E. coli with immobilised TiO2 10
-2
Solar UV irradiance (W m )
6
Spring & Summer seasons Initial concentration Final concentration
-1
E. coli (CFU mL )
5
10
4
10
50 40 30
Spring and summer th May 8 2004 nd July 2 2004 th April 20 2005 th September 30 2005
20 10 0 10:00
3
10
SPRING AND SUMMER (UVmax:38-45wm-2).
-2
Max.~ 45 W m
12:00
14:00
16:00
18:00
20:00
Local time
2
10
Detection limit
1
10
4.63
5.72
9.85
10.79
13.12 -1
QUV (kJ L )
C. Sichel, et al. Catalysis Today 2007, in press.
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Weather conditions Disinfection of E. coli with immobilised TiO2
-2
Solar UV irradiance (W m )
6
10
Autumn &Winter seasons Initial concentration Final concentration
-1
E. coli (CFU mL )
5
10
4
10
3
10
AUTUM AND WINTER (UVmax: 28-38Wm-2).
50 -2
40
Max.~ 38 W m
30 20
Autumn and winter th October 27 2004 th January 30 2004 th February 11 2005 th November 28 2005
10 0 10:00
12:00
14:00
16:00
18:00
20:00
Local time
2
10
1
10
Detection limit
3.33
3.47
3.83
3.95
4.04 -1
QUV(kJ L )
C. Sichel, et al. Catalysis Today 2007, in press.
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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. -66Ankara University 8-11 October 2007
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Inactivation of C. parvum Sodis and solar photocatalysis with fixed TiO2 Global Irradiance (Wm-2)
100 80
Viability (%)
1000
SODIS Real Sunlight SPCDIS Real Sunlight 750 Control
60 40
500
250
DAY 1
0 0
20
4
DAY 3
DAY 2 8
12
16
20
24
Cumulative Exposure Time (h) C. parvum oocysts
0 0
10
20
30
40
50
60 -2
Cumulative Global Exposure (MJ m ) F. Mendez-Hermida, et al. J. Photochem. Photobiol. A, 88 (2007) 105-111.
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Photocatalytic inactivation Fusarium
F. equiseti F. antophilum F. verticillioides F. solani F. oxysporum
Concentration (CFU/mL)
1000
100
10
1 0
2
4
6
8
QUV (kJ/L)
10
12
14
C. Sichel, et al. Appl. Cat. B: Environ., 74 (2007) 152-160.
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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 chemicalchemical-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
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Applications Design of the final system for disinfection of drinking water 1
5
4
3
1. PV panel 2. & 3. Solar Photo-reactor 4. Pump 5. Electric box 6. Connections
2 6
S. Malato et al., Review, Catalysis Today 122 (2007) 137-149.
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Applications Final reactor systems in South-America and North-Africa
Photo Energy Center. Cairo, EGYPT
ESTF. Fez, MOROCCO
IMTA. Morelos, MEXICO.
CNEA. Tucumán, ARGENTINA
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Applications SODISWATER project Solar Disinfection of Drinking Water for Use in Developing Countries or in Emergency Situations Partners: 1. RCSI 2. UU 3. CSIR 4. EAWAG 5. IWSD 6. CIEMAT 7. UL 8. ICROSS 9. USC
(IRELAND) (UK) (SOUTH AFRICA) (SWITZERLAND) (ZIMBABWE) (SPAIN) (UK) (KENYA) (SPAIN)
Objetive: The objective of this project is the development of an implementation strategy for the adoption of solar disinfection of drinking water as an appropriate, effective and acceptable intervention against waterborne disease for vulnerable communities in developing countries without reliable access to safe water, or in the immediate aftermath of 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.
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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. -73Ankara 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.
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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.
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THANKS Dr. Pilar Fernández Ibáñez
[email protected] Plataforma Solar de Almería –CIEMAT Ministerio de Educación y Ciencia www.psa.es
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