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

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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

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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

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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

Questions?

Terry KeepECT Sales ManagerTrojanUV(519) 457-3400tkeep@trojanuv.com

www.trojanuv.com