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 Like florescent bulbs except: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)

Lo

g S

urv

ival

0% inactivated

90% inactivated, 10% surviving

99% inactivated, 1% surviving

99.9% inactivated, 0.1% surviving

99.99% inactivated, 0.01% surviving

99.999% 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 J/m160 J/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 1300

BACTERIABacillus anthracis (6,4)

Bacillus subtilis (6)Corynebacterium diphtheriae

E.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

/AN

SI 5

5 R

equi

red

Min

imum

Flu

ence

...

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

Lo

g R

emo

val

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 := p

4 · n · · RHOi,j2

· exp –(w · R · RHOi,j

R

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

LimitationsLimitations

Add 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 Testing

All UV-Tube All UV-Tube DesignsDesigns

• 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 + 0.2918

R2 = 0.9656

0

1

2

3

4

5

6

70 200 400 600 800 1000 1200 1400

Fluence (Dose) J/m2

Lo

g R

emo

val

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

Lo

g S

urv

iva

l

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 Degradation

Interactions of UV-Tube Materials with Interactions of UV-Tube Materials with UV in the presence of water…UV 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 Test for volatile organic compounds and metals.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 Studies

Cycling 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