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+ O - FH Münster

UV-Strahlungsquellen für die Wasseraufbereitung
Anwendung in der Trink-,
Prozess- und Abwasserbehandlung
Thomas Jüstel
tj@fh-muenster.de
Münster
03. Mai 2006
FH Münster, FB 1
Prof. Dr. T. Jüstel
UV Radiation Sources
for Water Treatment
Outline
• Introduction
• UV Radiation: Effects and Applications
• UV Radiation Sources
• Treatment of
– Drinking water
– Waste water
– Process water
• Future Trends
FH Münster, FB 1
for Water Treatment
Dynamic of Worldwide Water Use
6000
water consumption / 109 m3
5000
agriculture
industry
household
total
Facts and Figures
• during the last 100 years worldwide
water consumption increases twice
as fast as world population
• 0.6% of the global water resources is
available as drinking water
4000
• 1.2 billion people have no access to
safe drinking water
3000
• 3 billion people suffer from diseases
caused by contaminated water
2000
• unclean water kills more than
2 million people, mostly children,
each year
1000
0
1900
FH Münster, FB 1
1950 year 2000
2050
Increasing demand for efficient + low
cost water treatment technologies
for Water Treatment
Worldwide Disinfection Market
1999
2500 Mio. €
2005
3800 Mio €
Chlorination
55%
Chlorination
83%
Ozone,
Filtration,...
5%
Ultraviolet
12%
Ozone,
Filtration,...
15%
Ultraviolet
30%
• Moderate total market growth (7% p.a.)
• Strong tendency to replace chlorine based systems
• UV/ozone segments are growing super-proportionally
FH Münster, FB 1
for Water Treatment
Technology Benchmark
0.5
costs [€/m3]
0.4
0.3
0.2
0.1
0
Ultraviolet
Chlorine
Ozone
Filtration
Source: “Desinfektion von biologisch gereinigtem Abwasser”, Merkblatt ATV-M 205,
Deutsche Gesellschaft für Wasserwirtschaft, Abwasser und Abfall e.V. (1998)
FH Münster, FB 1
for Water Treatment
Advantages of UV Radiation
•
Direct method (effective, economic)
•
Easy installation
•
Broad range of microorganisms can be inactivated
(e.g. Cryptosporidium parvum oocysts, Giardia muris)
•
Safe and easy handling, storage, shipping (no harmful chemicals)
•
Minimum formation of disinfection by-products (DBPs)
•
No influence on odour and/or taste
•
No concentration and accumulation of viruses, bacteria or contaminants
FH Münster, FB 1
for Water Treatment
UV-Radiation: Effects and Applications
100 nm
UV-B
UV-C
VUV
200 nm
280 nm
UV-A
320 nm
12.5 - 6.9 eV
6.9 – 4.5 eV
Cleavage of H2O and
O2 into radicals
Ozone formation
Cleavage of C-C, CH, C-O bonds
Excitation of C=C
bonds
Excitation of
nucleobases
Cleavage of O3, ClO2
and H2O2
Vitamin D
production
Transcription of
repair enzymes
Cleavage of O3 and
NO2
Photocatalytic
reactions
Melanin oxidation
Decomposition of
organic pigments
Ultra pure water
TOC reduction
Wafer cleaning
Photochemistry
Disinfection of H2O
and air
Photochemistry
X-ray imaging
additive removal
Psoriasis treatment
Tanning
Water and air
purification by TiO2
photocatalyst
Tanning
FH Münster, FB 1
4.5 - 3.9 eV
400 nm
3.9 – 3.1 eV
for Water Treatment
UV-Radiation: Photochemistry by VUV
Effects on water on air components
1. Photochemical cleavage of water
H2O + hν(< 200 nm) → OH. + H.
2 OH. → H2O2
2 H2O2 → 2 H2O +1O2
2. Ozone formation
O2 + hν(< 200 nm) → 2 O.
2 O2 + 2 O. → 2 O3
3. Photochemical cleavage of carbon dioxide
CO2 + hν(< 230 nm) → CO + 1O
4. Photochemical cleavage of nitrate anion
NO3-+ hν(< 240 nm) → NO2. + O.Cleavage of Nitrogen occurs at wavelength < 120 nm
FH Münster, FB 1
for Water Treatment
UV-Radiation: Photochemistry by UV-C
Effects on H2O2 and O3
Extinktionskoeffizient H2O2
1. Cleavage of H2O2 into OH radicals (H2O2/UV process)
H2O2 + hν(< 280 nm) → 2 OH.
160
140
120
2. Conversion of Ozone into H2O2
O3 + H2O + hν(< 330 nm)
→ H2O2 + O2
H2O2 + hν(< 280 nm) → 2 OH.
Formation of OH. radicals is the key to
Advanced Oxidation Processes (AOPs):
OH. + M → OH- + M+
FH Münster, FB 1
100
80
60
40
20
0
200 210 220 230 240 250 260 270 280 290 300
Wavelength λ [nm]
for Water Treatment
UV-Radiation: Disinfection by UV-C
Biochemical background
Rel. efficiency/absorption
1,0
H
O
P
Disinfection efficiency (DIn 5031-10)
O
Absorption spectrum of dTMP
N
C
N
C
0,8
C O
C
CH3
H
0,6
P
O
0,4
C
N
0,2
H
O
P
0,0
200
250
300
O
350
FH Münster, FB 1
Extinction coefficient ε at 260 nm
15200 lmol-1cm-1
8400 lmol-1cm-1
12000 lmol-1cm-1
7100 lmol-1cm-1
N
NH
C
H
O
O
C
N
C
H
C O
C
CH3
H
P
C O
C CH
3
C
C
N
Wavelength [nm]
Nucleotide
dAMP
dTMP
dGMP
dCMP
H
O
N
C
C O
CH3
for Water Treatment
UV-Radiation: Application in Water Treatment
UV disinfection (240 - 280 nm)
• domestic tap water
• municipal drinking water facilities
• surface water
• waste water disinfection
• process water (food / beverage industry)
Photo-initiated oxidation techniques (< 240 nm)
• oxidation/mineralization of toxic organic contaminants
• ultra pure water production
• drinking / process water treatment
• ground water remediation
• treatment of waste water (e.g. from hospitals)
FH Münster, FB 1
for Water Treatment
How much UV Radiation?
Standards and regulations
• NSF/ANSI Standard 55 (US)
• Class A (safe level): 40 mWs/cm2
• Class B (supplement): 16 mWs/cm2
• DVGW (Germany)
• 400 J/m2 (254 nm)
• verification with test organism
(E. coli, B. subtilis)
• reduction of 99.99 % = log 4
Some affecting factors
• Water flow / water quality
• Reactor design
• Lamp aging / performing
• Fouling of sleeve
• Type of microorganism (radiation hardness, photoreactivation, etc…)
Photoreactivation is a process whereby dimerized pyrimidines (usually thymines) in
DNA are restored by an enzyme (deoxyribodipyrimidine photolyase)
FH Münster, FB 1
for Water Treatment
Disinfection Efficacy - Parameters
Reactor
• Geometry
• Volume flow rate
⇒ Residence time
Water
• Quartz tube fouling
• Turbidity, particles
• Water matrix
Lamps
•
•
•
•
•
Total lamp power
Spectrum
Degradation
Power density
T-dependence
UV dose / Jm2
Microorganism
• UV sensibility
• Photo-reactivation
• Reproduction rate
FH Münster, FB 1
Reduction rate
for Water Treatment
Types of UV Radiation Sources
Sunlight
> 300 nm
Solar UV spectrum
UV-B
UV-A
Hg discharge lamps
• low pressure
• amalgam
• medium pressure
-2
-1
Spectral irradiance [Wm nm ]
1,0
185, 254 nm
185, 254 nm
200 – 400 nm
0,8
0,6
0,4
0,2
0,0
280
Excimer LASER
Solar radiation
at 60° sun height
(clear sky)
300
320
Excimer lamps (DBD)
• Xe2*
• KrCl*
• XeBr*
• XeCl*
172 nm „fluorescent DBD“
222 nm
282 nm
308 nm
(Al,Ga)N LEDs
260 – 380 nm
FH Münster, FB 1
340
360
380
Wavelength [nm]
for Water Treatment
400
Low Pressure Hg Discharge Lamps
Desired
Glass tube
Hg discharge
Phosphor
excited
layer
Hg atom
Hard UV Radiation
Purification
FH Münster, FB 1
spectrum
Radiation from
discharge
electrode
electrons
Phosphor
Disinfection
cap
Soft UV Radiation
Photochemistry
+ Photobiology
for Water Treatment
Low Pressure Hg Discharge Lamps
Lamp spectrum
Temperature dependence
254 nm
1,0
Mercury Low Pressure Discharge Efficiency
Pure Mercury
90
0,8
BiIn Amalgam
80
Relative Efficiency / %
Emission intensity [a.u.]
100
0,6
0,4
70
60
50
40
30
20
10
0,2
185 nm
0
0
365 nm
0,0
100
200
300
Wavelength [nm]
10
20
30
40
50
60
70
80
Temperature / °C
400
• Highest light output at 40°C gas temperature (coldest spot)
• Designed for 25°C ambient temperature
• 85% emitted at 253.7 nm, 12% at 185 nm, rest at 365 nm and in the
visible range
• Typical lifetime: 10.000 h
FH Münster, FB 1
for Water Treatment
Medium Pressure Hg Discharge Lamps
•
•
•
•
Main emission in the UV-A/UV-B range and visible radiation
Semi-continuum in the UV-C
Operation temperature: 600°C - 800°C
High power (density) + compact design ⇔ lower efficiency
FH Münster, FB 1
for Water Treatment
State-of-the-art UV Radiation Sources
UV-C wavelength
typical lamp power
lamp efficiency
GAC factor
UV-C power per length
wall temperature
Low Pressure Hg
Amalgam
Medium Pressure Hg
254 nm
254 nm
200 - 280 nm
4...100 W
100...300 W
1...17 kW
< 40 %
30...35 %
10...15 %
85 %
85 %
80 %
0.2 W / cm
0.7 W / cm
15 W / cm
40 °C
100 °C
600 - 900 °C
⇒ selection based on life cycle cost
FH Münster, FB 1
for Water Treatment
UV Radiation Application Areas
•
•
•
•
Municipal drinking water
Private households (POU / POE)
Swimming pools / spas
Ships
•
•
•
•
•
•
Food / beverage industry
Pharmaceutical industry
Personal care products (e.g. cosmetics)
Semiconductor / microelectronic industry
Aquaria
Aquaculture / fish farms
•
•
•
Municipal waste water
Industrial waste water
Hospital waste water
FH Münster, FB 1
for Water Treatment
Municipal Drinking / Waste Water
Goal: Inactivation of microorganism
•
•
•
•
•
•
Driven by government regulations
Disinfection by-products (drinking water)
Replacement of chlorination systems
Life cycle costs and system performance critical
Installation sizes up to 7.6.106 m3/day
Only few global players on the market
FH Münster, FB 1
for Water Treatment
Municipal Drinking Water
Location: Helsinki, Finland
Flow rate: 12.500 m3/h
UV Power: ∼ 22 kW
Number of lamps: ∼ 170
Power/lamp: ~ 130 W
FH Münster, FB 1
for Water Treatment
Waste Water Treatment
Location: Bad Toelz, Germany
Flow rate: 200 … 2000 m3/h
UV Power: 18 kW
Number of lamps: 144
FH Münster, FB 1
Location: Manukau, New Zealand
Flow rate: 50.400 m3/h
UV power: min. ~ 320 kW
Number of lamps: ~ 2500
for Water Treatment
Industrial / Commercial Process Water
Goal: Disinfection and TOC reduction
•
•
•
•
•
More diversified market
Compact installations
Relatively low flow rates
High level of purity
Industrial/commercial customers
– Food beverage
– Micro electronics
– Bio pharmaceutical
– Hospitals
– Fish farms
– Hydroponics
– etc…
FH Münster, FB 1
for Water Treatment
End Consumer Market
Goal: Purification of domestic drinking water
•
•
•
•
•
POU / POE Applications
Very diversified market
Small flow rates or batch processes
Discontinuous use
Driving market forces
– Safety
– Handling
– Design
– Marketing
– Sales channels
FH Münster, FB 1
for Water Treatment
Future Trends
1. Advanced Oxidation Processes
„More than only disinfection“
2. Incoherent Excimer Lamps
„Novel UV sources for novel applications“
FH Münster, FB 1
for Water Treatment
Approach
- direct photolysis of contaminants
- production of oxidizing intermediates
mainly •OH
Laws of photochemistry
• „Only the light that is absorbed by a molecule
can be effective in producing photochemical
change in the molecule“, Grotthus-Draper Law
(1817, 1843)
• „Each molecule taking part in a chemical
reaction absorbs (at least) one quantum of
radiation (photon), which causes the reaction“,
Stark-Einstein Law (1912)
• „The energy of an absorbed photon must be
equal or greater than the weakest bond in the
molecule“, conservation of energy
FH Münster, FB 1
for Water Treatment
Homogeneous catalysis
a) VUV water photolysis
H2O + hν → H. + OH.
b) UV + ozone
O3 + hν → O2 + O(1D)
O(1D) + H2O → [OH. + .OH] → H2O2
H2O2 + hν → 2 OH.
c) UV + hydrogen peroxide
H2O2 + hν → 2 OH.
Oxidizing agent Oxidation potential
[V vs NHE]
Fluorine
3.03
Hydroxyl radical
2.80
Atomic oxygen
2.42
Ozone
2.07
Hydrogen peroxide
1.78
Perhydroxyl radical
1.70
Hypobromous acid
1.68
Chlorine dioxide
1.57
Hypochlorous acid
1.49
Chlorine
1.36
d) UV/Vis Fenton processes
Heterogeneous catalysis
• TiO2 + UV/Vis (+H2O2)
FH Münster, FB 1
for Water Treatment
Contaminants and Waste Treated by AOPs
amino acids
antibiotics
arsenic
chromium
coliforms
cyanide
disinfection by-products
distillery wastewater
hospital wastewater
insecticide
landfill leachat
municipal sludge
FH Münster, FB 1
natural organic matter
oilfield wastewater
olive mill wastewater
paper mill effluent
phenolic wastewater
printing wastewater
rubber process wastewater
seed corn wastes
spent caustic
tannery wastewater
volatile organic compounds (VOCs)
x-ray contrast media
for Water Treatment
Basic physical principle
• formation of excited dimers (excimer) in the gas phase
(or excited complexes (exciplexes), e.g. in OLEDs)
• gas pressure: 100 mbar....1 bar (high pressure lamps)
Lamp driving (energy in-coupling)
• by microwaves
• by dielectric barrier discharge
non-thermal plasma
Typical gas fillings
• rare gases
• halides
• rare-gas/halide mixtures
FH Münster, FB 1
for Water Treatment
Excimer Forming Gases or Gas Mixtures
Pure
Halide
Ar
Kr
Xe
FH Münster, FB 1
F
Cl
Br
I
Noble Gas
158 nm
258 nm
293 nm
342 nm
-
-
Ar*2
~10%
126 nm
> 10%
193 nm
> 10%
248 nm
> 10%
351 nm
ca. 5%
175 nm
18%
222 nm
14%
308 nm
< 0.1%
161 nm
ca. 5%
207 nm
15%
282 nm
< 0.1%
185 nm
Kr*2
~15%
146 nm
ca. 5%
253 nm
Xe*2
30%
172 nm
for Water Treatment
Dielectric barrier microdischarges generating excimer radiation
HV-electrode (semi-transparent)
u(t)
discharge gap
dielectric layer (glass, quarz)
Xe filling
UV-R
characteristic parameters
tMD
≈ 10 ns
pressure
1 bar
172 nm gap
1 mm – 1 cm
Egap
0.1 – 100 kV / cm
Telectron
1 – 10 eV
1014 cm-3
nelectron
degree of ionization 10-4
f
50 kHz
dielectric layer (glass, quarz)
counter electrode
FH Münster, FB 1
for Water Treatment
Advantages of DBD driven Xe excimer discharges
• Instant start
• Temperature independent
• Flexible design
• Specific output spectrum
• High power density
Reaction scheme
Xe + e-
→ Xe(3P2) + e-
Xe(3P2) + 2 Xe
→ Xe2(3Σu+) + Xe
Xe2(3Σu+)
→ 2 Xe + hν172 nm
FH Münster, FB 1
XERADEX (Radium)
Present application areas
• Plasma display panels (PDPs)
• Lamps for scanners and copiers
• Surface cleaning
• Ozone production (Siemens)
• Water treatment
for Water Treatment
DBD driven Xe-excimer discharge lamp for water treatment
Optimised lamp design
• solely 172 nm radiation (quartz)
• FWHM ~ 14 nm
• Radiant efficiency ~ 40%
at 20 or 100 W of electrical
input power
15 – 25 kW XeCl* excimer
lamps are in use
From: T. Oppenländer, E. Sosnin, IUVA
News 7 (2005) 16
FH Münster, FB 1
for Water Treatment
Normalized emission intensity
Hg low pressure discharge lamp
UV Phosphor layer
254 nm
1,0
185 nm
254 nm
0,8
0,6
0,4
0,2
185 nm
Desired lamp
spectrum
0,0
200
300
400
500
600
Wavelength [nm]
Xe2* excimer discharge lamp
172 nm
Wavelength [nm]
FH Münster, FB 1
2 nd Continuum
1st Continuum
Resonance Line
Emission intensity
147 nm 150 nm
150 nm
172 nm
German Patent
DE 199 19 169.7
Lamp glass
for Water Treatment
2 nd Continuum
1st Continuum
Resonance Line
147
Xenon Excimer 10
-7
10
H2O
1
-1
-6
10
-5
10
-4
10
-3
10
-2
10
160
170
180
190
200
10
0
10
Wavelength [nm]
to improve penetration depth
FH Münster, FB 1
Penetration depth [m]
Absorption coefficient [m-1]
-8
10
7
10
6
10
5
10
4
10
3
10
2
10
10
0
10
150
emission spectrum
convert to 200 - 280 nm
convert to 190 - 200 nm
8
Xe excimer
172
Wavelength [nm]
Rel. efficiency/absorption
Intensity [a.u.]
Phosphor Conversion of Xe Excimer Radiation
Disinfection efficiency (DIN 5031-10)
1.0
0.8
0.6
0.4
0.2
0.0
200
220
240
260
280
300
320
Wavelength [nm]
to improve GAC overlap
for Water Treatment
Philips Project “UV-C Phosphors” since 07/05
Project goals
Development and optimization of novel UV-C phosphors for fluorescent
lamps based on Xe2*-Excimer discharges
Find UV-C phosphors with a large GAC overlap
⇒ Pr3+ activated phosphors
1,0
Germicidal Action Curve
LaPO4:Pr
225 nm
0,8
Lamp spectrrum of a
DBD lamp with YPO4:Pr
YPO4:Pr
233 nm
LuBO3:Pr
257 nm
YBO3:Pr
261 nm
Intensity (a.u.)
1.
0,6
0,4
0,2
Y2SiO5:Pr
270 nm
0,0
200
250
300
Wavelength [nm]
FH Münster, FB 1
for Water Treatment
350
Philips Project “UV-C Phosphors” since 07/05
Project goals
2.
Optimise efficiency and stability of materials with high GAC overlap
Present status
•
Phosphor efficiency ~ 90 … 100%
•
Lamp efficiency ~ 20 … 25%
•
Phosphor stability improvement measures
Highly efficient, pulse driven
Xe excimer discharge lamp
comprising a UV-C phosphor
under development to achieve 10000 h lifetime
FH Münster, FB 1
for Water Treatment
Acknowledgement
FH Münster
Dr. Julian Plewa
Philips Research Aachen and Philips Lighting Roosendaal
Dr. Wolfgang Schiene
Dr. Arjan van der Pol
Thanks for your attention!
FH Münster, FB 1
for Water Treatment

+ O - FH Münster

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