iuva uv oxidation conference: uv oxidation for recalcitrant contaminants
DESCRIPTION
UV Oxidation has been successfully employed for many difficult-to-treat contaminants in drinking water. This presentation is an overview of some those applications.TRANSCRIPT
UV-Oxidation for Recalcitrant Chemical Contaminants:
Successes, Challenges and Future Applications
IUVA AOP Conference: International Experience and PerspectivesDecember 16, 2013
• UV technology is used ubiquitously for
drinking water disinfection
• Rising populations result in decreasing
availability of “pure” water sources
• Contaminants infiltrate water sources in
a variety of ways
• Agricultural run-off
• Wastewater discharge
• Many contaminants cannot be treated
through conventional approaches
WATER QUALITY – GLOBAL TRENDS
COMPLEX CONTAMINANT DESTRUCTION
• Many contaminants are removed
through conventional filtration
• Contaminants exist which, due to
specific chemical or physical
properties, are more recalcitrant
– Various pesticides
– 1,4-Dioxane
– Nitrosamines
• Such contaminants require more
advanced treatment approaches
ENVIRONMENTAL CONTAMINANT TREATMENT (ECT)
Using UV and hydrogen peroxide to destroy trace organic contaminants
in water by:
UV-Photolysis
UV-Oxidation
ECT OVERVIEW - EQUIPMENT
Hydrogen Peroxide (H2O2)
• Oxidant added to treated water
immediately upstream of UV
reactor
Ultraviolet (UV) System
• Inactivate microorganisms and
converts H2O2 to hydroxyl
radicals which, in turn, oxidize
molecular contaminants
UV-PHOTOLYSIS
Chemical Bonds are
Broken by UV Light
UV-OXIDATION
Hydrogen
peroxide
Hydroxyl
radical
Chemical bonds are
broken by hydroxyl
radicals
ECT TECHNOLOGIES FOR RECALCITRANT COMPOUNDS
• Potassium Permanganate
– Weaker oxidant, limited effectiveness
• Powdered Activated Carbon
– Low capital but limited effectiveness, high maintenance, added sludge
• Granular Activated Carbon
– Large footprint, high capital, frequent & expensive change-outs
• Ozone
– Effective in many applications; complicated system and bromate
• UV-Oxidation
– Increasing global experience, effective for many compounds,
simultaneous disinfection, overcoming challenges such as quenching
OZONE AND CONTAMINANT TREATMENT
• Ozone molecules have lower oxidation potential than hydroxyl radicals
• Ozone alone has limited efficacy against certain contaminants that can
be treated through advanced oxidation with hydroxyl radicals
– NDMA
– Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX): an explosive agent
– Methyl tert-butyl ether (MTBE): an additive to gasoline
• Additional concerns related to the formation of potentially harmful
chemical by-products (bromate)
– Hall WTW (Anglian Water)
FILTRATION AND CONTAMINANT TREATMENT
• Activated carbon has varying affinity for contaminants
– It is a “removal” technology and not a “break-down” technology
• Some contaminants are resistant to more advanced filtration approaches
such as reverse osmosis
– Molecules with low molecular weight and high polarity can pass through RO
membranes
• UV-oxidation is often applied after RO to destroy recalcitrant
contaminants
– NDMA
UV-OXIDATION APPLICATIONS
CASE STUDIES OF CONTAMINANT TREATMENT
TASTE AND ODOR, ALGAL TOXINS
• Influenced by warm temperatures
and nutrient runoff (algae growth)
• Earthy and musty odors can be
detected at concentrations of 10
nanograms per liter or less
• T&O compromises public confidence
in the safety of the water
– Less water sold impacts cash
flow/existing debt service
UV-OXIDATION FOR TREATMENT OF ALGAE-DERIVED
CONTAMINANTS
90% Removal
LORNE PARK WATER TREATMENT PLANTRegion of Peel, (Serving Mississauga/Brampton, Ontario, Canada)
• Largest UV-oxidation installation for
taste and odor treatment in the world
– Flow rate = 390 MLD
• Both UV-oxidation and ozone
technologies were evaluated
• UV-oxidation was selected:
− Smaller footprint
− Safety (no LOX required on site)
− Simplicity
• Residual peroxide quenched with
activated carbon
OTHER UV-OXIDATION INSTALLATIONS TREATING T&O
Project Name Location Flow (MLD) Date Operational
Lorne Park Water Treatment Plant, Region of Peel Ontario, Canada 390 2011
Aurora Reservoir Water Treatment Facility California, USA 189 2010
Cornwall Water Treatment Plant Ontario, Canada 100 2006
Neshaminy, Pennsylvania (Aqua PA) Pennsylvania, USA 57 2010
Shenango, Pennsylvania (Aqua PA) Pennsylvania, USA 57 2011
Robert W. Sokoll Water Treatment Plant Texas, USA 53 2010
Patoka Lake Water Treatment Plant Indiana, USA 39 2013
Alliance Water Treatment Plant Ohio, USA 38 2013
Mansfield Water Treatment Plant Texas, USA 28 2011
Midlothian Water Treatment Plant Texas, USA 15 2013
West Elgin Water Treatment Plant Ontario, Canada 14 2010
Otter Lake Illinois, USA 13 2013
Hanover Water Treatment Plant Ontario, Canada 13 2011
Groesbeck Water Treatment Plant Texas, USA 8 2008
Lucerne Water Treatment Plant California, USA 4 2008
METALDEHYDE
• Pesticide used to eliminate slugs
• European pesticide regulations
limit individual pesticide
concentrations to 0.1 ppb
• Metaldehyde is not easily removed
through adsorption methods
– Frequent GAC replacements
– Observances of desorption back
into water supply
• Required ozone concentrations
� bromate
HALL ROAD WTW, LINCOLN, UNITED KINGDOM
• Anglian Water treating Trent River
water
• UV-oxidation selected due to:
– Concerns with ozone and bromate
– Inefficiencies with activated carbon
• Facility uses 1 kW TrojanUVSolo™
Lamp/Driver technology
• 3 UV reactors (96 Low-pressure
lamps each), 4th being added
1,4-DIOXANE
• Found in groundwater plumes
containing volatile organic
contaminants (VOCs)
• Very stable molecule; not volatile
– Air stripping not effective
– Activated Carbon ineffective
– Passes through reverse osmosis
• Recent cancer risk level set by EPA at
0.35 ppt
GREENBROOK, REGION OF WATERLOO, ONTARIO
• 5 wells extracting from a 1,4-
dioxane-contaminated source
• Engineers concluded air
stripping and GAC ineffective
for 1,4-dioxane
• Pilot Testing Included:
– UV/H2O2
– Ozone/H2O2
– UV/TiO2
• UV-oxidation system provides
1.3-log removal of 1,4-dioxane
from local groundwater.
1.39
1.281.3
1
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
50 L/s 75 L/sLo
g R
ed
uct
ion
(1
,4-D
ioxa
ne
)
Actual
Guaranteed
GREENBROOK, REGION OF WATERLOO, ONTARIO
• Medium Pressure System
– Existing facility was small with little
room to expand
– MP have small footprint and were
easily retrofitted
• GAC quenching
• Also credited for both
Cryptosporidium and Giardia
Inactivation
ARTESIAN WATER COMPANY NEWARK, DELAWARE
• Bis-2,chloroethyl ether
(BCEE), 1,4-dioxane, PCE
and TCE in groundwater due
to impacts from industry and
landfill
• Existing GAC/airstripper
ineffective for removal of 1, 4
dioxane
55.2
8.7
0 0.140
10
20
30
40
50
60
70
1,4-Dioxane BCEEC
on
cen
tra
tio
n o
f C
on
tam
ina
nt
(ug
/L)
Initial Concentration
After Treatment
ARTESIAN WATER COMPANY NEWARK, DELAWARE
• GAC for quenching peroxide
• 8.33 MLD, 2-TrojanUVPhox
D72AL75s, 8 ppm peroxide, 2-log
of 1,4-dioxane and 1.7-log BCEE
• May 2014 installation
2-D72AL75 stacked in production
UV-OXIDATION INSTALLATIONS TREATING 1,4-DIOXANE
Project Name City/State/CountryFlowrate
(MLD)
Date
OperationalType of Reactor
Groundwater Replenishment System Orange County, CA, USA 378.30 2008 Low Pressure
Aurora Reservoir Water Purification Facility Colorado, USA 189.15 2010 Low Pressure
Gibson Island Advanced Water Treatment Plant Brisbane, Australia 99.81 2009 Low Pressure
Luggage Point Advanced Water Treatment Plant Brisbane, Australia 69.87 2008 Low Pressure
West Basin Municipal Water District California, USA 47.29 2006 Low Pressure
San Gabriel Valley Water Company Site B5 California, USA 42.52 2006 Low Pressure
San Gabriel Valley Water Company Site B6 California, USA 42.52 2005 Low Pressure
Valley County Water Company California, USA 42.52 2005 Low Pressure
Middleton Water Treatment Plant Waterloo, ON, Canada 40.30 2012 Medium Pressure
Bundamba Advanced Water Treatment Plant Brisbane, Australia 19.97 2008 Low Pressure
La Puente Valley County Water District California, USA 13.63 2002 Low Pressure
Greenbrook Drinking Water Plant Waterloo, ON, CA 12.94 2008 Medium Pressure
Stockton Groundwater Remediation California, USA 1.09 2001 Low Pressure
Honeywell Groundwater Treament Facility Hollywood, CA, USA 1.09 2012 Low Pressure
Mystic Lake Casino Minnesota, USA 0.55 2009 Low Pressure
Plymouth Arizona, USA 0.33 2011 Low Pressure
El Monte California, USA 0.27 2009 Low Pressure
University of San Jose California, USA 0.14 2010 Low Pressure
Secor International/Federal Denver Facility Colorado, USA 0.11 2006 Low Pressure
GEI Burlington Burlington, MA 0.08 2008 Low Pressure
Kansas State University Landfill Kansas, USA 0.08 2011 Low Pressure
TREATMENT OF RDX: HASTINGS, NEBRASKA USA
• Former Naval Ammunition Depot contaminated groundwater
• Treatment of RDX (Hexahydro-1,3,5-trinitro-1,3,5-triazine)
• Collimated beam bench-scale testing demonstrated significant RDX
reductions with increased UV exposure
– Degrades through photolysis only
• USACE awarded project after 35 years of study. 4.37 MLD of
groundwater treatment online by end of 2013
• Unmanned facility
– Easy operation with heightened energy efficiency with low-pressure lamps
UV-PHOTOLYSIS APPLICATION – HASTINGS, NE
UV-OXIDATION APPLICATIONS
FUTURE CHALLENGES
BY-PRODUCT FORMATION
• Regulated THMs/HAAs as well as assimilable organic carbon (AOC) can
be formed/increased with UV-oxidation
– Highly dependent on water quality
– Pre-evaluation of site water and site-specific parameters is vital
• Quenching approach is an important consideration
– GAC removes most residual and by-product precursors before chlorination
– GAC/BAC also effectively removes nitrite in medium pressure applications.
USE OF BIOLOGICALLY ACTIVE CARBON (BAC)
• Low levels of GAC quenches
peroxide to negligible levels
• Few change-outs required
– Especially compared to using AC
for direct contaminant removal
• Biologically Activated Carbon
demonstrates effective
quenching
– Even less frequent change-outs
than with GAC
– 2 min EBCT achieves >1-log
removal
BAC Quenching
0
1
2
3
4
5
6
7
5 10
EB
CT
to
Ach
iev
e 9
7%
Re
du
ctio
n in
H2O
2R
esi
du
al (
Min
)
Initial H2O2 Concentration (ppm)
OVERCOMING CHALLENGES OF UV-OXIDATION
• ECT systems require more UV energy than disinfection
• As a result, installed ECT systems often require larger lamp
counts
– Maintenance: Fouling and Cleaning
– High energy demand
• Need for more efficient UV-systems with fewer lamps
– Anglian Water Installation
• Investigating alternative oxidants
– UV + chlorine is an example
CONCLUSIONS
• UV-oxidation used to treat a variety of recalcitrant contaminants
– Surface water (T&O, algal toxins, pesticides, PPCPs)
– Groundwater (1,4-Dioxane)
• Applications drive lamp technology that favor either low-pressure OR
medium-pressure
– Medium Pressure = Seasonal Use / Small Footprint
– Low Pressure = Consistent Year-Round Use / Energy Efficiency
CONCLUSIONS
• Experience is key
– No two contaminants are the same
– Reactor efficiency is unique and needs to be understood for sizing and
performance
– Translating design from paper to performance has its technical challenges
(Inexperienced Contractors, piping, peroxide mixing, disinfection
requirements, footprint restrictions)
– These are not turn-key products
– Extensive piloting, internal research and full scale experience with the
actual reactor is needed to meet Performance Guarantee