NON-ECONOMIC ADVANTAGES OF UV-OXIDATION FOR 1,4-DIOXANE TREATMENT New York s Water Event April 25, 2017
WATER QUALITY GLOBAL TRENDS 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 Industrial Many contaminants cannot be treated through conventional approaches
COMPLEX CONTAMINANT DESTRUCTION Many contaminants are removed through conventional filtration Contaminants exist which, due to specific chemical or physical properties, are more recalcitrant 1,4-Dioxane Various pesticides Algae Derived Contaminants (Toxins and T&O) Such contaminants require more advanced treatment approaches
CONTAMINANTS - 1,4-DIOXANE 1,4-Dioxane is a solvent stabilizer used to prevent solvent breakdown during degreasing operations No current federal regulations for 1,4- dioxane. However, the USEPA has included 1,4-dioxane in its third unregulated chemical contaminants list Properties of 1,4-dioxane Formula C 4 H 8 O 2 Molecular Weight Structure 88.15 Conventional treatment technologies such as reverse osmosis (RO), coagulation/filtration, and carbon adsorption are ineffective in removing 1,4-dioxane
CONTAMINANTS - 1,4-DIOXANE Monitored as a Result of USEPA UCMR3 State # Samples Samples Above MRL* % New York 205 91 44.39% South Carolina 48 17 35.42% Pennsylvania 87 21 24.14% New Jersey 169 38 22.49% Colorado 86 15 17.44% North Carolina 95 14 14.74% California 711 97 13.64% Georgia 92 11 11.96% Michigan 44 5 11.36% *MLR = 0.07 µg/l
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 (H 2 O 2 ) Oxidant added to treated water immediately upstream of UV reactor Ultraviolet (UV) System Inactivate microorganisms and converts H 2 O 2 to hydroxyl radicals which, in turn, oxidize molecular contaminants
UV-PHOTOLYSIS Chemical Bonds are Broken by UV Light
UV-OXIDATION Hydroxyl radical Hydrogen peroxide Chemical bonds are broken by hydroxyl radicals
ECT TECHNOLOGIES FOR RECALCITRANT COMPOUNDS Potassium Permanganate Weaker oxidant, limited effectiveness, no disinfection Powdered Activated Carbon Low capital but limited effectiveness, high maintenance, added sludge, no disinfection Granular Activated Carbon Large footprint, high capital, frequent & expensive change-outs, no disinfection Ozone Effective in many applications; complicated system and bromate
BEST AVAILABLE TECHNOLOGY FOR 1,4 - DIOXANE TREATMENT 1,4-Dioxane is highly soluble Low Henry Constant (4.8 x 10-6 atm-m 3 /mol) Converting 1,4-dioxane into a gaseous phase though air-stripping is not effective Very stable in water and is difficult to remove 1,4-dioxane commonly found in addition to VOCs Air Stripping Aeration Tower
SMALLER FOOTPRINT UV reactors can be easily installed and stored and require minimal building footprint Often UV systems can be stored in existing groundwater pump houses to limit construction costs Hydrogen peroxide equipment can be stored outdoors Alternative technologies like air stripping require large tanks and/or towers Air Stripping Aeration Tower
NO DISPOSAL REQUIRED Methods like air stripping DO NOT break-down contaminants Transfer to Air and to Carbon (Usually) An emerging concern is that currently there little oversight on how collected contaminants are disposed UV-oxidation instantly breaks down treatment. Downstream disposal of collected contaminants or oxidation byproducts is not required.
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 OXIDANT OXIDATION POTENTIAL (Volts) Fluorine 3 Hydroxyl Radical 2.8 Ozone 2.1 Hydrogen Peroxide 1.8 Chlorine 1.4 Additional concerns related to the formation of potentially harmful chemical by-products (bromate)
FILTRATION AND CONTAMINANT TREATMENT Activated carbon has varying affinity for contaminants It is a removal technology and not a break-down technology Inconvenient and costly change-outs and backwashing 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
TUCSON AIRPORT REMEDIATION PROJECT -TARP USEPA Superfund Site Air stripping adopted in mid-90 s to remove trichloroethene (a VOC) 1,4-dioxane was discovered in the groundwater in 2002 and was widely distributed in the groundwater plume. Concentrations ranged between 1 ppb and 3 ppb (Health Advisory = 0.07 ppb) Air Stripping ineffective 17
TUCSON AIRPORT REMEDIATION PROJECT -TARP Third-Party Piloting of Suitable Mitigation Technologies Low-Pressure UV-AOP Medium-Pressure UV-AOP Ozone/H2O2 Pilot report completed at the end of 2010 All effectively treated 1,4-dioxane to desired limits (>2-Log Removal) Ozone/H 2 O 2 generated bromate Formation depended on ratio of ozone to H2O2 dosed. Concentrations ranged from 5 to 60 ppb (MCL = 10 ppb) LOX on-site was not desired for safety (explosive) 18
TUCSON AIRPORT REMEDIATION PROJECT -TARP UV-AOP Selected Concerns about bromate and the desire to not have to balance two chemicals to avoid DBP formation Simultaneous treatment of other VOCs in the groundwater (TCE) Concerns over nitrite formation with medium-pressure technology favored a low-pressure UV solution 19
TUCSON AIRPORT REMEDIATION PROJECT -TARP 5,800 gpm (1317 m 3 /hr) Largest UV-oxidation installation in the world treating groundwater primarily for 1,4-dioxane. 6 TrojanUVPhox D72AL75 reactors. 1.6-Log 1,4-dioxane removal Commissioned in late-2013 and performance testing confirmed in early 2014 Treated effluent re-injected into aquifers which do not have 1,4-dioxane and is used to serve 50,000 residents in the Tucson area. 20
LLANGOLLEN WELL-FIELDS (ARTESIAN WATER) - DELAWARE Site was initially designed to treat Bis- 2-Chloroethyl (BCEE) with GAC Frequent break-through and replacements (6 months) 1,4-dioxane detected at the site in 2013 Third-party evaluation carried out by Hatch-Mott MacDonald (Now Mott MacDonald) to evaluate economic and non-economic benefits of: UV/AOP Ozone/H 2 O 2
LLANGOLLEN WELL-FIELDS (ARTESIAN WATER) - DELAWARE Economic Advantages Civardi, et al., 2014 Non-Economic Advantages Easy to Integrate Minimal Training More Automated GAC Relief Used for H 2 O 2 Quenching
UV-OXIDATION IS HIGHLY AUTOMATED System Control Center ensures that appropriate concentrations of oxidant are used Power automatically adjusted Individual chambers turned on/off automatically Detected lowest lamp-aged chamber to operate Research based UV intensity targets programmed into control system
UV-OXIDATION INSTALLATIONS TREATING 1,4-DIOXANE Project Name City/State/Country Flowrate (MLD) Date Operational Type 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
UV-OXIDATION APPLICATIONS FUTURE CHALLENGES
QUENCHING Quenching approach is an important consideration Hydrogen peroxide remains after passing through the UV system and must be removed. Chlorine is a reducing agent that removes peroxide Generally already a requirement for chlorine residual in distribution system Need to maintain proper dosing to ensure regulated residual levels Activated carbon filter beds Higher cost but heightened simplicity GAC change-outs when quenching H2O2 are very infrequent (1-2 change-outs throughout system life
USE OF BIOLOGICALLY ACTIVE CARBON (BAC) Low levels of GAC quenches peroxide to negligible levels BAC Quenching Biologically Activated Carbon demonstrates effective quenching Even less frequent change-outs than with GAC 2 min EBCT achieves >1-log removal EBCT to Achieve 97% Reduction in H 2 O 2 Residual (Min) 7 6 5 4 3 2 1 0 5 10 Initial H 2 O 2 Concentration (ppm) Also effective against nitrite when using medium-pressure
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 Effective piloting Improving efficiency
CONCLUSIONS Drinking water becoming more difficult to treat 1,4-dioxane a prevalent contaminant in New York State Full-scale treatment facility on Long Island expected to be on-line in May 2017 UV-oxidation used to treat a variety of other recalcitrant contaminants T&O, algal toxins, pesticides, PPCPs, VOCs Advanced contaminant treatment projects require a significant amount of feasibility study and piloting Treatability is a consideration but rarely a determining factor
CONCLUSIONS Costs (CAPEX and OPEX) do play a significant role Non-economic advantages also considered Avoiding downstream toxic by-products (bromate) Simplicity of installation and operation Ability to treat multiple contaminants Experience of supplier (These are NOT turn-key) Non-economic advantages applied to quenching solutions
Questions? Scott Bindner Market Analyst TrojanUV (519) 457-3400 sbindner@trojanuv.com www.trojanuv.com