uv for developing countries
DESCRIPTION
UV For Developing Countries. A new tool for the disinfection toolbox?. UV Disinfection. Prof. Bill Larsen’s system. First UC Berkeley UV Tube. Next Model. Sri Lankan Neighborhood Scale Installation. B9 Plastics Better Water Maker. Ultra-Violet Light. UVA (315 – 400 nm): sun tans - PowerPoint PPT PresentationTRANSCRIPT
UV For Developing CountriesUV For Developing Countries
A new tool for the A new tool for the disinfection toolbox?disinfection toolbox?
UV Disinfection
Prof. Bill Larsen’s Prof. Bill Larsen’s systemsystem
First UC Berkeley UV Tube
Next ModelNext Model
Sri Lankan Neighborhood Scale Sri Lankan Neighborhood Scale InstallationInstallation
B9 Plastics Better Water B9 Plastics Better Water MakerMaker
Ultra-Violet Light
UVA (315 – 400 nm): sun tans
UVB (280 – 315 nm): sun burns
UVC* (200 – 280 nm): disinfection
(*Nearly 100% filtered by the atmosphere.)Interferes with DNAReplication/
Reproduction
History of UV Drinking Water Disinfection
•1910 Marseilles, France: UV is first used to treat drinking water. Abandoned for free chlorine (by-product of soda production)
•1970’s: Disinfection by-products discovered. UV disinfection of drinking water common in Europe.
•1990’s: Outbreaks in the US lead to concern that chlorine is not effective against some organisms.
•March 1993: a cryptosporidium outbreak in Milwaukee leads to 400,000 illnesses and 100+ deaths.
History of UV Water Disinfection
•1999: Town of Ontario, NY becomes the first community in North America to disinfect surface source drinking water with UV light.
•Currently: there are over 1500 wastewater treatment plants using UV in the US.
Lake Ontario
Poly-alum added
SedimentationGravel, sand, and GAC filters
Chlorine residual added
Storage
UV
UV System ComponentsUV System Components• UV Bulbs and Ballast (AC or DC)UV Bulbs and Ballast (AC or DC)
– Mercury-argon lamps (an electrical arc Mercury-argon lamps (an electrical arc ignites the mercury vapor which emits UV ignites the mercury vapor which emits UV light)light)
– HopeHope for LEDs in the future…for LEDs in the future…• ChamberChamber• Quartz SleeveQuartz Sleeve
– passes UVpasses UV– maintains bulb temperaturesmaintains bulb temperatures
• Sensor Sensor – to monitor bulb outputto monitor bulb output
• Cleaning MechanismCleaning Mechanism
Mercury Vapor BulbsMercury Vapor Bulbs• Like florescent bulbs except:Like florescent bulbs except:
– Quartz not glassQuartz not glass– No phosphor coatingNo phosphor coating
• 88% of the output at 253.7 88% of the output at 253.7 nmnm
• Lamp is susceptible to Lamp is susceptible to cooling by the effluentcooling by the effluent
• Limited Lamp Life—1 year Limited Lamp Life—1 year continuous operationcontinuous operation
Determining Dose (Fluence)
Dose (Fluence) = Intensity * Dose (Fluence) = Intensity * Exposure Exposure
TimeTimeJ/mJ/m22) (W/m) (W/m22) ) (s) (s)
Function of bulb and water characteristics
Function of hydrodynamics
&
Geometry of reactor
Simple Microbial Response
Dose Response Curve for E. Coli (wild type) (Sommer et al, 1998)
-6
-5
-4
-3
-2
-1
0
0 10 20 30 40 50 60 70 80 90 100
UV Fluence or Dose (J/m2)
Log
Surv
ival
0% inactivated90% inactivated, 10% surviving
99% inactivated, 1% surviving
99.9% inactivated, 0.1% surviving
99.99% inactivated, 0.01% surviving99.999% inactivated, 0.001% surviving
A More Complicated Response
and imbedded bacteria
?
Explanation of Shoulder
•Threshold of DNA “hits” to inactivate?
•Reactivation?
Explanation of Tailing
•“Shielding” depends on particle absorbance
•Imbedded bacteria
•UV resistant bacteria
TurbidityTurbidity• Can lead to scattering, reflection, blocking of microorganisms Can lead to scattering, reflection, blocking of microorganisms
by particlesby particles• Considered negligible up to 5 NTUConsidered negligible up to 5 NTU• Theoretically, overall intensity is not reduced, but, energy is Theoretically, overall intensity is not reduced, but, energy is
lost through interactions with particulateslost through interactions with particulates• Embedded microorganisms present the real limitationEmbedded microorganisms present the real limitation• Precede by filtration or flocculation/sedimentationPrecede by filtration or flocculation/sedimentation
Absorption CoefficientAbsorption Coefficient• Certain particles absorb at germicidal wavelengthsCertain particles absorb at germicidal wavelengths• Fe, sulfites, aromatic organics, humic acid, dechlorination with Fe, sulfites, aromatic organics, humic acid, dechlorination with
Sodium ThiosulfateSodium Thiosulfate• Presence can greatly increase attenuationPresence can greatly increase attenuation
Water CompositionWater Composition
USUS• 1966: Dept. Health, Education & Welfare – 1966: Dept. Health, Education & Welfare – 160 160
J/mJ/m22
• 1999: NY State still required 1999: NY State still required 160 J/m160 J/m22 when I when I started working with UVstarted working with UV
• ~2000: WHO Recommends ~2000: WHO Recommends 380 J/m380 J/m22
• 2002: ANSI/NSF Standard 55 set at 2002: ANSI/NSF Standard 55 set at 400 J/m400 J/m22
UV Regulatory StandardsUV Regulatory Standards
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300BACTERIA
Bacillus anthracis (6,4)Bacillus subtilis (6)
Corynebacterium diphtheriaeE.coli (1,6,4)
Legionella pneumophila (1,4)Micrococcus speroides (4)
Proteus vulgaris (6,4)Salmonella typhi (1)
Pseudomonas aeruginosa (1,4)Salmonella enteritis (1,4)
Salmonella typhimurium (6,4)Shigella dysenteriae (1,4)
Shigella paradysentaeriae (1)Shigella flexneri (1)
Shigella sonnei (1,4)Staphylococcus albus (6)
Staphylococcus aureus (1,4)Streptococcus hemolyticus (6,4)
Streptococcus lactis (6,4)Streptococcus viridans (6,4)
Vibrio cholerae (1,4)
VIRUSESPoliovirus 1 (1,3,3,8)
Coliphage (1,4)Hepatitis A virus (1,3,3,10)Rotavirus SA 11 (1,3,3,10)
Adenovirus 40 (8)Adenovirus 41 (8)
PROTOZOAGiardia muris (1)
Acanthamoeba castellanii (1)Cryptosporidium parvum (9)
UV Dose (J /m2)
1 LOG (90%)2 LOG (99%)3 LOG (99.9%)4 LOG (99.99%)
NSF/A
NSI 5
5 Req
uired
Mini
mum
Flue
nce .
..
Estimation of Dose Estimation of Dose (Fluence)(Fluence)
• Biological Assays with VirusBiological Assays with Virus– Develop dose (fluence) inactivation relationship Develop dose (fluence) inactivation relationship
with Quasi Collimated Beam Apparatuswith Quasi Collimated Beam Apparatus– Measure Log inactivation in UV deviceMeasure Log inactivation in UV device
Magnetic Stir Plate
Collimating Box
Concentric Apertures
Petri Dish with sample and stir bar
UV Bulb
Manual UV Shutter
Quasi Collimated UV rays
Aluminum Plate
Bulb Holders
MS2 Colifage response to MS2 Colifage response to UVUV
y = 0.0043x + 0.2918R2 = 0.9656
0
1
2
3
4
5
6
70 200 400 600 800 1000 1200 1400
Fluence (Dose) J/m2
Log
Rem
oval
Log Removal5/12/20055/7/20053/25/20052/28/20052/5/200510/27/20045/9/20044/19/2004NWRI HighNWRI LowLinear (Log Removal)
•Chemical ActinometryChemical Actinometry– Photochemical reaction Photochemical reaction
rate rate •Molecules react with UV Molecules react with UV photosphotos
•Products of the reaction Products of the reaction used to determine quantity used to determine quantity of photons absorbed (dose)of photons absorbed (dose)
Estimation of DoseEstimation of Dose
Dose Estimation: Dose Estimation: Point Source Point Source SummationSummation
)INTENSITYi,j := p4 · n · · RHOi,j2
· exp –(w · R · RHOi,jR
RHO i,j := (x – y)2 + R2
R
Intensity
x
RHO
y
σw= abs of water
•Bulb is considered a line of point sources distributing light equally in all directions•Intensity at each point is calculated as the sum of all point sources
• No known byproductsNo known byproducts• Short contact time (sec, instead of min)Short contact time (sec, instead of min)• No danger of overdosingNo danger of overdosing• Ability to inactivate cyst forming Ability to inactivate cyst forming
organisms (e.g. Giardia, Cryptosporidium) organisms (e.g. Giardia, Cryptosporidium) at doses used for water treatmentat doses used for water treatment
• No transportation of hazardous chemicalsNo transportation of hazardous chemicals
Benefits of UVBenefits of UV
• No residual No residual disinfectantdisinfectant
• Photoreactivation Photoreactivation and dark repair and dark repair possiblepossible
• Bulb foulingBulb fouling– Organic constituents, Organic constituents,
hardness, algae and hardness, algae and biofilm on quartz biofilm on quartz sleevesleeve
• Requires electricityRequires electricity
LimitationsLimitationsAdd chlorine residual
Shield from visible light for 1-2 hrs Overdose
Clean sleeveSuspend bulb
65 cm
water outlet
water level
Side View(transparent)
G-8 germicidal UV bulb
Design: ss-PVCDesign: ss-PVC
Ferro Cement UV-TubeFerro Cement UV-Tube
Outlet
Water
Ferro cement trough
Bulb
Nut and BoltBallast
Metal Cover
Ferro cement cover
Cable
Figure 1: Cross Section and Side View of the Ferro Cement UV-Tube
Inlet
Laboratory TestingLaboratory TestingAll UV-Tube DesignsAll UV-Tube Designs• Microbial TestingMicrobial Testing• Hydrodynamic Tracer Hydrodynamic Tracer
Tests Tests • Materials Degradation Materials Degradation
TestingTesting
Bulb StudiesBulb Studies• CyclingCycling• Warm-Up TimeWarm-Up Time
Constant Head Tank
Flowmeter
Mixing Tank with Pump
UV-Tube
MS2 MS2 Challenge Challenge
TestTest
MS2 Microbial TestingMS2 Microbial Testing
y = 0.0043x + 0.2918R2 = 0.9656
0
1
2
3
4
5
6
70 200 400 600 800 1000 1200 1400
Fluence (Dose) J/m2
Log
Rem
oval
Log Removal5/12/20055/7/20053/25/20052/28/20052/5/200510/27/20045/9/20044/19/2004NWRI HighNWRI LowLinear (Log Removal)
MS2 Challenge of the UV-Tube
-6
-5
-4
-3
-2
-1
0
0 1 2 3 4 5
Test
Log
Surv
ival
Avg: 4.38 95% CI: 2.98 – 5.77
643 1292967
MS2 Fluence Response Curve
Rhodamine Tracer TestingRhodamine Tracer Testing
• Pulse input with syringePulse input with syringe• Samples every 3 Samples every 3
secondsseconds• Measure on Measure on
spectrophotometer 555 spectrophotometer 555 nmnm
Tracer Test, ss-PVC UV-Tube at 5 L/min
0
0.01
0.02
0.03
0.04
0.05
0 50 100
Time (s)
% o
f Dye
Exi
ting
4/25/2005
4/29/2005
5/5/2005
5/7/2005 New Design
Date4/25/2005
4/29/2005
5/05/2005 5/7/2005 New Design
35.2 36.5 35.8 36.4
tbar36.1
7 35.5 34.5 35.7
q/tbar 0.97
1.03
1.04 1.03
Materials DegradationMaterials DegradationInteractions of UV-Tube Materials with UV Interactions of UV-Tube Materials with UV
in the presence of water…in the presence of water…– Flow through, minimal flow.Flow through, minimal flow.– Overnight test, 16 hours.Overnight test, 16 hours.– Vacation test, 8 days. Vacation test, 8 days. – Total Evaporation, 35 days. Total Evaporation, 35 days.
Test for volatile organic compounds and metals.Test for volatile organic compounds and metals.
Materials Degradation Materials Degradation ResultsResults• PVC alone PVC alone carcinogenic volatile organics carcinogenic volatile organics• ABS alone ABS alone Benzene! Benzene!• Galvanized steel Galvanized steel High zinc levels (taste) High zinc levels (taste)• Lined PVC Lined PVC low levels of vocs, acceptable low levels of vocs, acceptable• Stainless with PVC endcaps Stainless with PVC endcaps low levels, low levels,
acceptableacceptable• Copper and aluminum have not been Copper and aluminum have not been
tested.tested.
Bulb StudiesBulb StudiesCycling StudyCycling Study• One cycle daily: 12 One cycle daily: 12
hours on, 12 hours hours on, 12 hours offoff
• Four cycles daily: 3 Four cycles daily: 3 hours on, 3 hours off hours on, 3 hours off
• Twelve cycles daily: Twelve cycles daily: 1 hour on, 1 hour off1 hour on, 1 hour off
Warm up StudyWarm up StudyCycling Timers
Bulb Covers
UV Issues/ChallengesUV Issues/Challenges• Electricity requirementsElectricity requirements• Safety: UV exposure and electric shockSafety: UV exposure and electric shock• Material interactions with UVMaterial interactions with UV• Water depth and hydraulics (UV dose)Water depth and hydraulics (UV dose)• Water CharacteristicsWater Characteristics
– Embedded BacteriaEmbedded Bacteria– Fe, sulfites, aromatic organics, humic acid, & Fe, sulfites, aromatic organics, humic acid, &
dechlorination with sodium thiosulfate absorb UVdechlorination with sodium thiosulfate absorb UV• Safe storage (no residual disinfectant)Safe storage (no residual disinfectant)• Bulb lifeBulb life• *****Dissemination **********Dissemination *****
Important Facts:Important Facts:• UV is bad for your eyes, skinUV is bad for your eyes, skin• Turbidity, chemicals affect UV Turbidity, chemicals affect UV
transmittancetransmittance• Bulb life is limitedBulb life is limited• Water depth and hydraulics are Water depth and hydraulics are
importantimportant• No residual disinfectantNo residual disinfectant
Materials and UV-CMaterials and UV-C• Blocks UV:Blocks UV:
– GlassGlass– PlexiglassPlexiglass
• Transmits UV:Transmits UV:– QuartzQuartz– TeflonTeflon
• Reflects UV:Reflects UV:– AluminumAluminum
• Reacts with UV:Reacts with UV:– PVCPVC– ABSABS– Other plastics?Other plastics?
Design Features:Design Features:• EffectiveEffective
– Eliminate microorganismsEliminate microorganisms• Portable or built in placePortable or built in place
– Size, weightSize, weight– ConstructionConstruction
• Simple Simple – Local materialsLocal materials– Simple toolsSimple tools
Design Features:Design Features:• Reliable Reliable
– Easy operationEasy operation– Little maintenance requiredLittle maintenance required– Long term useLong term use
• Cheap!Cheap!• Fast (2 lpm or more)Fast (2 lpm or more)• SafeSafe
– NO UV ExposureNO UV Exposure– Visual cue telling if light is on or notVisual cue telling if light is on or not
ChallengesChallenges• Compatible with 15 W (G15T8) or 30 Compatible with 15 W (G15T8) or 30
W (G30T8) UV bulbW (G30T8) UV bulb• 12 V DC or 110 V AC ballast12 V DC or 110 V AC ballast• Flow regulationFlow regulation• FiltrationFiltration• Uniform and optimal UV exposureUniform and optimal UV exposure
The Biggest Challenge:The Biggest Challenge:
Final production price:Final production price:
< $100 US< $100 US