Incorporating Innovative Approaches into New UV Disinfection SystemsTodd Elliott, P.ERegional Solutions Leader – Drinking Water & Reuse

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Presentation Outline Disinfection Background

UV Disinfection Examples

Virginia UV Case Studies

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Public Water Supply Disinfection Practices:100 Years and Counting

• The first continuous chlorination of municipal drinking water began in 1902 (the town of Middlekerke, Belgium)

• Sodium hypochlorite was used in 1908 to provide the first continuous disinfection of municipal drinking water in the U.S.

• The first plant to use Ozone was in 1906 (Nice France)

• ACE 1914 - “It is a matter of common knowledge nowadays that the ultraviolet rays have a strong bactericidal power.”

1930s – filtration plus chlorine disinfection virtually eliminates waterborne illnesses in US

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“New” Treatment Challenges

• Non-Regulated Disinfection Byproducts

• Contaminants and Pathogens of Emerging Concern

• Raw Water Ammonia

• Taste & Odor

• Algal Toxins

• Increased Public Awareness and Scrutiny

• Large Distribution System with Reduced Demands

• Greater Water Storage Requirements

• Nitrification

• Limited O&M Budgets

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Recent Timeline for Key Disinfection Regulations

-IESWTR-Stage 1

DDBP

LT1ESWTRDraft UVDGM

LT2ESWTRFinal UVDGM

Seattle Public Utilities

New York CityDEP

MilwaukeeCrypto

Outbreak

-LT2ESWTROperational

Compliance Dates-Stage 2 DDBP

Round 2Crypto

Sampling

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LT2ESWTR Round 2 Crypto Sampling Impacts

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Example Round 2 Sampling = Bin 2

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Multiple Treatment Alternatives Available

2- Stage Lime Softening

Enhanced Ozone Disinfection

Combined Filter Effluent

Individual Filter Effluent

UV DisinfectionWatershed Protection

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UV Disinfection Lamp Technologies

Low-Pressure, High Output (LPHO)– Lower energy use– Monochromatic light @ 254nm– Lamp Life: >12,000 hours– Larger reactor, more lamps

Medium Pressure (MP)– Higher energy use– Polychromatic light 200-300nm– Lamp Life: 5,000-9,000 hours– Smaller reactor, fewer lamps

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Applied UV Dose Varies by Validation Challenge Organism Used

UV Reactors typically validated off-site by 3rd party per USEPA UV Disinfection Guidance Manual (UVDGM, 2006)

– MS2 Phage – most common

– T1 and T7 Phage are also used

UVDGM, 2006

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Addressing Low Wavelength Issues for Medium Pressure UV Lamps

• WRF/EPA/AWWA Project 4376 (Linden et al., 2015)

• Wavelengths < 240 nm– Inactivation of validation test organisms (MS2,

T1UV, T7) >>> target organisms (Crypto)

• Need to account for these differences to avoid overstating UV reactor disinfection performance with respect to Cryptosporidium

– Look up tables developed with most conservative ASCF

• F(Log I, UVT, Validation Organism, Sleeve Type, Validation Water Source)

– Variable ASCF Equation

• F(Log I, UVT)

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New Research Conducted to Improve ASCFAccuracy

• Validation-Specific and Site-Specific ASCF for MPUV Project 4478 (Wright et al, 2017)

• CFD modelling completed to determine ASCF for 6 commercial MPUV reactors at 9 WTPs

• Validation specific ASCF equations developed

• Existing Utility Example:

– 2-log Crypto, T1UV, >93% UVT

– Fixed ASCF = 1.50

– Lookup Table ASCF Range

• 1.18 – 1.80

– Validation Specific ASCF

• 1.1 – 1.25

– Unable to turn down lamp power further at normal operating conditions to reduce power consumption

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Significant Energy Cost Savings With LPHO UV and T1 RED

$0

$20,000

$40,000

$60,000

$80,000

$100,000

$120,000

$140,000

$160,000

MS2 RED 40 MS2 RED UVDGM T1 RED UVDGM

MP LPHO

Basis for Capital SizingTo meet NYS DOHRequirements

Basis for Operating Dose

95% UVT$0.14/kWh2 log Crypto (2 sites)3 log Giardia (1 site)

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Common Taste and Odor Control Treatment Approaches

• Powdered activated carbon (PAC)• Ozone (alone or with hydrogen peroxide)• Biological filtration (BAC or BAF)• UV advanced oxidation process (AOP)• Granular activated carbon (GAC) adsorption

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What is UV Advanced Oxidation? Definition: water treatment with

the use of UV light (photolysis) in combination with hydroxyl radical (advanced oxidation) Hydrogen peroxide fed

upstream UV light destroys photo-

sensitive compounds UV light converts H2O2 to OH.

radical: hydroxyl radical = very

powerful oxidant Destroys contaminants – other

technologies transfer them to another phase

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UV AOP is a combination of Oxidation and Photolysis

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

7 ppm H2O2 14 ppm H2O2 7 ppm H2O2 14 ppm H2O2 7 ppm H2O2 14 ppm H2O2

Che

mic

al L

og R

educ

tion

per U

nit o

f Pow

er D

raw

UV-OxidationUV-Photolysis

TCE

NDMA

1,4-Dioxane

*Courtesy of Trojan Technologies, Inc.

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UV AOP Removes T&O Compounds

( )

y = 0.0018xR2 = 0.991

y = 0.0011xR2 = 0.999

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 100 200 300 400 500 600 700 800 900

Collimated Beam UV Dose (mJ/cm2)

Log

Geo

smin

Rem

oval

UV AOP with Peroxide Dose of 11 mg/LUV AOP with Peroxide Dose of 6 mg/LUV Alone (No Peroxide Added)

3-log Crypto Dose

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Example UV + UV AOP Operation

UV

UV

UV

UV

H2O2

Disinfection Only UV AOP Mode

30%-50% Power

Off 100% Power

100% Power

Algal ToxinsMIB, GeosminPathogens

Pathogens

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UV Disinfection or UV AOP is also a critical treatment process for water reuse applications

PRETREATMENT MEMBRANE FILTRATION

REVERSE OSMOSIS

UVADVANCED OXIDATION

STABILIZATION AND

DISINFECTION

COAG

ULAN

T

HYDR

OGEN

PE

ROXI

DE

LIME

CO2

CHLO

RINE

SLUDGE BACKWASHCONCENTRATE

RECYCLED WATER TO USERS

SECONDARY EFFLUENT

FROM EXISTING

WWTP

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Process Schematic – Treatment Objectives

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SWIFT Facility – 3D

UV Building

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Aurora, CO: Combining the Best of Natural and Engineered Purification Steps as Multiple Barriers

Taste and Odor

Color

TDS

Nitrate

Pathogens

Organics

Micro-Pollutants

Natural Treatment Softening UV-AOP Filters GAC Blending

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1 to 4 log Removal of Nine Nitrosamines by UV AOP

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200

Collimated Beam UV Dose (mJ/cm2)

Log

Des

truc

tion

(Log

s)

NDMA NMEA NDEA

NDPA NPYR NMOP

NPIP NDBA NDPhA

5.0 mg/L of Hydrogen Peroxide Added to All Samples

NPIP

NDPhA

NDEA

NPYR

NDBA

NMOP

NDMA

NMEA

NDPA

68.4%

90.0%

99.97%

99.7%

96.8%

99.0%

99.997%

99.999%

99.99%

99.9%3-log Crypto Dose

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Provisions for Future Expansionand UV AOP

UV UV UV

UV

UV

UV

H2O2

Relative Disinfection Strength:1x 2x 4x

Add’l ContaminantRemoval (e.g. NDMA)

Add’lLamps

2nd

ReactorH2O2Addition

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Provisions for Future UV AOP

Space for AdditionalPanels/Ballasts

Future Reactors

Virginia Case Studies

City of PortsmouthLake Kilby WTF

City of Norfolk37th Street WTP

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City of Norfolk Department of Utilities

Raw Water Source– Reservoir System consisting of three

lakes in Suffolk and additional lakes in Norfolk and Virginia Beach

– Fed from Various Sources• Runoff to Drainage Area

• Lake Gaston

• Blackwater River

• Nottoway River

– Average TOC in Raw Water = 3-7 mg/l

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City of NorfolkDepartment of Utilities

City Operates Two Water Treatment Plants

37th Street (34 mgd)Moores Bridges (108 mgd)

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Project Drivers• Tropical Storm Irene Flushed Natural

Organic Material into Reservoirs in fall of 2011 and Stirred Things Up

– Raw Water TOC Levels and Finished Water DBP’s Increased in 2012

– Enhanced Coagulation Treated the Water and Regulatory Compliance Maintained but DBP Levels were Higher

• City Reviewed Finished Water DBPGoals and Lowered their THM Target

• This Series of Events Revealed the Vulnerability of Existing Phase III Disinfection Approach

Tropical Storm Irene

Stage 2 DBP Rule

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37th Street Water Treatment Plant Process Before Upgrades

Ammonia

Rapid Mix

Floc/Sed Filters Disinfection

In ClearwellsPump/

Storage Storage FW Pumps

Chlorine

DBP Control Strategy:─ Enhanced Coagulation with Ferric Sulfate at Depressed pH─ Chloramines in Distribution System

Limitations to chlorine CT reductions:─ Chlorinated filters for manganese control─ Clearwells located below sed basins contamination risk

required free chlorine residual

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New Multiple Barrier DisinfectionApproach Selected to Meet DBP and Disinfection Goals

Rapid Mix

Floc/Sed

New Filters

SWStorage Basin

Storage FW Pumps

New SW

Pumps

Low Lift

Pumps

ChlorineAmmoniaChlorine

UV

• Moved chlorine feed point to just upstream of new filters (after clearwells)• UV sized for up to 3.5-log giardia inactivation with one reactor out of service

– Conservative design MS2 RED = 40 mJ/cm2 + ASCF– Multiple Virus/Giardia disinfection barriers (filters + chlorine + UV)

• Ammonia added immediately downstream of UV, shorter chlorine CT• Maintain existing water storage volumes

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37th Street WTP Site Layout

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37th Street Plant - 3D View

UV Building

Finished Water Tank

Filter BuildingFilter Backwash EQ Basin

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UV Disinfection Reactors by TrojanUV

• Long-Time Manufacturers of UV Disinfection Equipment

• Medium Pressure UV Design

• Reactors Validated in Accordance with EPA UVDGM

• Maximum Flow per Reactor = 25 mgd (17 mgd design)

• Reactor Size: 24-inch

• ASCF: Specified as 1.3, lowered per WRF calcs

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UV Installation

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UV Operations to Date• 3-log Crypto/Giardia ~16 mJ/cm2• Typical UVT ~93%• Off Spec Water < 0.05% by vol/mth• Sleeve Fouling

• Increased wiper frequency to remove iron

• 1 wiper jam occurred at startup

• Perform Weekly UVT analyzer checks (1 unit)

• Initial fouling/humidity issues

• Perform monthly UV intensity sensor checks (18 sensors)

• Submit monthly report to VDH

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City of Portsmouth Lake Kilby WTF -Time Line of Improvements

Filter Group 1Basins 4 & 5

Filter Group 2Basin 6

Phase I ImprovementsFilters 11 – 16

2 – 1.5 MG ClearwellsBW tank

Finished Water PumpsBackwash Pumps

Phase II ImprovementsNew Chemical Bldg.

Phase III Improvements

Super PulsatorsFilter Rehab

Phase IV Improvements

Deep Bed FiltersUV Disinfection

BW FacilitiesBW Supply

1946 1967 1982 19991986 2016

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Phase IV - Facility Plan Developed the “Road Map”

• Replacement of aging infrastructure (i.e. old filters, backwash supply pumps, etc..)

• Optimization of Organics removal

• Coagulation optimization

• RSSCT (carbon evaluation)

• Providing multiple barrier approach to safeguard finished water supply• Deep bed filters• UV disinfection• Chlorination 0

2

4

6

8

10

12

0.00

0.04

0.08

0.12

0.16

0.20

0.24

0.28

0.32

0.36

0.40

0.44

0.48

20 30 40 50 60 70 80 90

TOC

Conc

entr

atio

n [m

g/L]

UV 2

54 [a

bs/c

m]

FeCl3*6H2O Dose [mg/L]

Lake Kilby Ferric Chloride Dose Series Organics

UV-…TOC

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General Process Flow Diagram with Disinfection Benchmark

Super Pulsators (3)Raw WaterPumping

UV ReactorsIntermediate Pump Station

Granular Media Deep Bed Filters Clear well #1

Clearwell #2 Finished Water Pump Station

Rapid Mixer

Coagulant Addition (Ferric or Alum)

NaOH

NaMnO4(optional) Chlorine

ChlorineFuture/Planned Unit Processes

1 2

xx

0.5 Log inactivation0.51.01.52.02.53.03.54.04.55.05.56.0

2.5 Log Removal/Inactivation Credit

for GiardiaLog

Rem

oval

/Inac

tivat

ion

Minimum Log Removal/Inactivation for Giardia = 3.0

Minimum Log Removal/Inactivation for Viruses = 4.0

2.54 Log Inactivation

2.78 Log Inactivation

5.78 Log Inactivation

5.81 Log Inactivation

Ammonia

2.0 Log Removal/Inactivation Credit

for Viruses

Microbial/Virus Inactivation/Removal Profile

Chlorine Inactivation

UV Light Inactivation

Sample location, see sample table for details on water quality sampling.

Chloramines Inactivation

UV Reactors

Clearwell #1

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Lake Kilby Phase IV - Basis of DesignDeep Bed Filters• Leopold Block type S underdrains• Media retaining troughs• Simultaneous Air Scour/water backwash• 8 FiltersUV Disinfection• 4 reactors (3 duty, 1 standby)• Firm capacity = 36 mgd (12 mgd per reactor)• UV Transmittance = 90%• Design MS2 RED <= 40 mJ/cm2 + ASCF• Giardia Inactivation <=3.5 Log (Capable of 3-log Crypto)

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UV Disinfection Reactors by Calgon Carbon Corporation

• Long-Time Manufacturers of UV Disinfection Equipment

• Medium Pressure UV Design

• Reactors Validated in Accordance with EPA UVDGM

• Maximum Flow = 28 mgd each (12.2 mgd design flow)

• Reactor Size: 24-inch

• ASCF: Variable, calculated per WRF guidance

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Phase IV Design Challenges –Space LimitationsReusing the old sedimentation basins

Site of new filter building complex

Contractor Staging

Filters 11 – 16 converted to

UV process area

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3D Model of Water Treatment Facility

New Filter Complex and Administration

Area

New Filter Backwash Waste Tank and

Chemical StorageArea

New UV Disinfection Bldg.

New Settled Water Pump Station & Blower Bldg.

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Construction Phasing

Existing Filter Bldg. Converted to UV Disinfection Bldg.

New Mixing System for

Residuals Tank

New Parking For Plant Operations

Staff

New Filter Backwash Tank and Chemical Facilities

Old Filter Bldg. Converted to Blower Building

New Electrical Bldg.

Additional Space for Expanding Plant

New Administration Bldg. and Filter

Complex

Phase I Construction

Phase II Construction

Phase III Construction

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Closing Thoughts

• Multi barrier disinfection is the new normal

• Disinfection is evolving, but still the cornerstone of public health protection

• Identify opportunities to optimize design to gain multiple benefits

Thank you!