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Incorporating Innovative Approaches into New UV Disinfection SystemsTodd Elliott, P.ERegional Solutions Leader – Drinking Water & Reuse
2
Presentation Outline Disinfection Background
UV Disinfection Examples
Virginia UV Case Studies
3
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
4
“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
5
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
6
LT2ESWTR Round 2 Crypto Sampling Impacts
7
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
9
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
10
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
11
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)
12
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
13
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)
14
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
15
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
16
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.
17
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
18
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
19
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
20
Process Schematic – Treatment Objectives
21
SWIFT Facility – 3D
UV Building
22
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
23
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
24
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
25
Provisions for Future UV AOP
Space for AdditionalPanels/Ballasts
Future Reactors
Virginia Case Studies
City of PortsmouthLake Kilby WTF
City of Norfolk37th Street WTP
27
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
28
City of NorfolkDepartment of Utilities
City Operates Two Water Treatment Plants
37th Street (34 mgd)Moores Bridges (108 mgd)
29
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
31
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
32
37th Street WTP Site Layout
33
37th Street Plant - 3D View
UV Building
Finished Water Tank
Filter BuildingFilter Backwash EQ Basin
34
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
35
UV Installation
36
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
37
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
38
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
39
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
40
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)
41
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
42
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
43
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.
44
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
45
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!