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Terry Keep AWWA NYS Tifft Water Supply Symposium September 21, 2017 THE USE OF UV/PEROXIDE FOR TREATING ALGAL DERIVED CONTAMINANTS IN DRINKING WATER
Terry KeepAWWA NYS Tifft Water Supply Symposium
September 21, 2017
THE USE OF UV/PEROXIDE FOR TREATING
ALGAL DERIVED CONTAMINANTS IN
DRINKING WATER
2
WATER STRESS
IN AN
INTERCONNECTED
WATER SUPPLY
Sources of contaminants in our water supply:
- Industrial discharge
- Agricultural runoff
- Chemical releases
- Municipal Wastewater
InjectionWell
ExtractionWell
Nutrients increase in Algae Blooms Taste & Odour, Algal Toxins
3
EXAMPLES OF MICROPOLLUTANTS
Nitrosamines (e.g. NDMA)
Disinfection byproducts
Pesticides & Herbicides
Metaldehyde, Atrazine, Isoproturon, others
Petroleum Additives
Including MTBE
Pharmaceuticals & Personal Care Products
Includes potential endocrine disruptors
Taste & Odour CompoundsSeasonal occurrences of MIB, geosmin and others
Algal ToxinsChronic and acute effects from cyanobacteria-derived
toxins
4
TASTE & ODOUR, ALGAL TOXINS
Seasonal algae blooms occur in surface waters
Decaying algae blooms result in MIB, geosmin, algal toxins, other T&O compounds
Earthy/musty, fishy, swampy, grassy tastes & odours at low ppt concentrations
Difficult to remove with conventional technologies
T&O episodes compromise public confidence in the safety of the water
5
TASTE AND ODOUR TREATMENT STRATEGIES
• Potassium Permanganate
– Limited Effectiveness
• Powdered Activated Carbon
– Messy PAC & Sludge Handling, no Performance Guarantee
• Granular Activated Carbon
– Frequent & Expensive Change-outs, no Performance Guarantee
• Ozone
– Complicated System & Carcinogenic by-product (Bromate)
• UV-Oxidation
– Simple, Effective for T&O with Simultaneous Disinfection, Guaranteed
Performance for life of system
6
UV / H2O2 FOR TASTE AND ODOUR TREATMENT
UV Advanced Oxidation: Using UV and Hydrogen Peroxide to destroy trace organic contaminants in water by:
UV-Photolysis
UV-Oxidation
7
UV-PHOTOLYSIS
Chemical bonds arebroken by UV light
8
UV-OXIDATION
Hydrogen peroxide
Hydroxylradical
Chemical bonds arebroken by hydroxyl radicals
9
CONTAMINANT DESTRUCTION BALANCE
0.0
1.0
2.0
3.0
4.0
5.0
6.0
NDMA Atrazine Geosmin Microcystin-LR
UV
-Ph
oto
lys
is/U
V-O
xid
ati
on
Co
ntr
ibu
tio
n t
o T
ota
l
Co
nta
min
an
t R
ed
ucti
on
(re
lati
ve
to
ND
MA
)
UV + H2O2
UV Photolysis
10
ALGAL TOXINS OXIDIZED MORE EASILY THAN MIB
APPLICATION OF UV ADVANCED
OXIDATION FOR TASTE & ODOUR /
ALGAL TOXIN TREATMENT
12
DUAL-MODE OPERATION
13
UV-OXIDATION A RANGE OF T&O COMPOUNDS
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
geosm
in
2-
meth
ylis
oborn
eol
(2-M
IB)
dim
eth
yl tr
isulfid
e
cis
, 4-h
epta
nal
trans,
trans,
2,4
-
hepta
die
nal
cis
-3-h
exenyl
aceta
te
Earthy Musty Swampy Fishy Rancid fish Grassy
(sweet)
Perc
en
t R
em
oval
Performance
Target
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COMPOUNDS GENERATED BY SOME CYANOBACTERIA
Geosmin
2-Methylisoborneol (MIB)
GSM and MIB can be detected by sensitive individual down to 4 ng/L (ppt)
[Geosmin] have been measured > 3000 ng/L
Aesthetics: T&O cmpds
Cylindrospermopsin (CYN)
Microcystin-LR (MC-LR) [MC]~1800ug/L meas drng bloom
Public Health: Cyanotoxins
SYSTEM SIZING
Contaminant Quantum Yield
Contaminant - Hydroxyl Radical Rate Constant
Contaminant Molar Absorption Coefficient
Hydrogen Peroxide Concentration
Water Absorbance (UVT)
Water Matrix Hydroxyl Radical Scavenging Capacity
Lamp Type
SIZING FACTORS FOR ECT SYSTEMS
UV-PHOTOLYSIS AND UV-OXIDATION KINETICS
Hydrogen peroxide
Hydroxylradical
The overall kinetic equation describing the photolytic and UV/H2O2
photo-oxidative reactions of a micropollutant C is:
][][][(
2][
][][
22
300
200
0
300
200
0
22
2222
SkOHkCkV
FFNCk
V
FFN
Ckdt
Cd
SOHC
OHSOHCCSC
UV-Photolysis UV-Oxidation
Fraction of light absorbed by contaminant, scavengers, and peroxide (fxn of wavelength, dependent on absorbance)
Lamp Spectral Photon Flux
Reaction rates with hydroxyl radical for contaminant (C) and scavengers (S)
Quantum Yield of contaminant and peroxide
Where:22
,, OHSC FFF
0N
k
CASE STUDIES
Aqua PA’s Neshaminy WTP, PennsylvaniaHatch Mott MacDonald Presented at New Jersey, Ohio and Pennsylvania Annual AWWA Conferences 2010
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Researchers Evaluated the following Treatment Technologies:
• PAC
• GAC
• Ozone
• UV AOP
Aqua PA’s Neshaminy WTP, PennsylvaniaHatch Mott MacDonald Presented at New Jersey, Ohio and Pennsylvania Annual AWWA Conferences 2010
Design Conditions:
• Flow rate: 57 MLD, average 40 MLD
• Design UVT: 93%
• Influent [GSM]: 100ppt
• Target effluent [GSM]: 10ppt
• 1.0-log GSM treatment at average flow, 0.7 log at peak flow
20
21
Estimates were based on a PAC dose of 30 mg/l and a 90-day taste and odor
period
22
Analysis was based on 90 days of taste and odor operation with a discount factor of 4%. Costs
include capital, construction, operation and maintenance (including dry solids removal for spent
PAC). The PAC costs were based on $0.95 per pound and $215 per ton of dry solids removal and
a dose of 30mg/L.
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Estimates were based on a PAC dose of 30 mg/l and a 90-day taste and odor period.
UV-oxidation was also evaluated over the same 90 day taste and odour period.
UV Reactor Chamber
Cooling Water Inlet
Cooling Water
Outlet
UV Reactor Chamber
UV Reactor UV Reactor
Cooling Water Inlet
Alliance Ohio T&O:Planning and Engineering Approach to the Final Design
o UV Oxidation System Feasibility Study
o UV Oxidation System Procurement
o UV Oxidation System Final Design Documents
o Design Criteria:
• UVT 92%
• Turbidity < 0.06 NTU
• TOC < 3 mg/l
• Nitrates < 1 mg/l
• pH 6.7 – 6.9
• Average Flow 5.5 MGD/10.0 MGD Max
UV Oxidation System: Procurement
• Bid items
– Clear and specific
– Bid Requirements
– Financial Stability
• Experience and Past Performance
– Demonstration of successful Operations
– Equipment Service and Support
• Equipment Characteristics and Flexibility
– Future Capacity
– Operations and Complexity
UV Oxidation System: Effective Integration of Quality and Cost
• Designed to meet the Client and Project Goals
• Balanced between Cost and Non-Cost Factors
• Qualifications/Experience Emphasis
• Broad Spectrum of Evaluation
UV Oxidation System:Final Design Documents
• Two Trojan SWIFTECT 30-Inch Diameter Reactor in Series
• Cooling System for Use During Filter Backwash Operations
• Operator Input During Chlorine Trouble Times
• Dedicated Automatic Chlorinator for UV Ox Operation
• System Bypass During Non- Taste and Odor Season
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REGIONAL MUNICIPALITY OF WEST ELGIN, ON
Source water is Lake Erie
Flow rate 14.4 MLD
Treatment train: coagulation/settling membranes UV-oxidation final disinfection
Algal blooms in late summer/early autumn
Previously used Powder Activated Carbon for T&O (membrane fouling)
Designed for 1.3-log Geosmin and 1.0-log MIB, algal toxins
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REGIONAL MUNICIPALITY OF WEST ELGIN, ON
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PERFORMANCE RESULTS WEST ELGIN, ONTARIO (APRIL 2009)
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CONCLUSIONS
• UV-Oxidation (UV + H2O2) is being implemented worldwide
• UV-Oxidation successfully destroys taste and odor compounds, algal toxins, other micro pollutants
• Performance Guarantee: Guaranteed Removal vs. competitive products
• On/Off technology (no event, no O&M)
• Disinfection design for UVDGM
• Barrier for PPCPs/future regulations
• Excellent option post membrane (no PAC)
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QUESTIONS?
THANK YOU
Terry Keep
Trojan Technologies
(519) 457-3400
