1. ROLE IN TREATMENT OF EMERGING CONTAMINANTS IN NORTH CAROLINA UV & OZONE MEDIATED ADVANCED OXIDATION Paul Hargette & Bryan Townsend B&V Water Technology Group NC AWWA-WEA 95 TH ANNUAL CONFERENCE

2. AGENDA UCMR 3 & 1,4-Dioxane in NC Waters 1,4-Dioxane Characteristics Ozone & UV Advanced Oxidation Conclusions 2

3. UCMR 3 & 1,4-DIOXANE IN NC WATERS 3

4. Monitoring of contaminants suspected to be present in drinking water Not currently regulated May warrant future regulation under the SDWA 30 Contaminants 28 chemicals and 2 viruses 12 month monitoring period from Jan 2013 – Dec 2015 Approximately 3,500 participating systems nation wide 3 RD UNREGULATED CONTAMINANT MONITORING RULE (UCMR 3) 4

5. Assessment Monitoring (List 1 Contaminants) 7 Volatile organic compounds 1 Synthetic organic compound (1,4-Dioxane) 6 Metals 1 Oxyhalide anion 6 Perfluorinated compounds Screening Survey (List 2 Contaminants) 7 Hormones Pre-Screen Testing (List 3 Contaminants) 2 Viruses UCMR 3 CONTAMINANTS 5

6. 1,4-DIOXANE IN NORTH CAROLINA 6 Source: UCMR 3 Database (through June 2015) Participating NC PWSs, Total & with 1,4-Dioxane Source Waters for PWSs with 1,4-Dioxane

7. Source: UCMR 3 Database (through June 2015) DISTRIBUTION OF 1,4-DIOXANE DATA 7 MRL = 0.07 μg/l

8. 1,4-DIOXANE CHARACTERISTICS 8

9. Industrial solvent stabilizer (e.g. TCA) Commercial products Paint strippers, dyes, greases, varnishes, waxes, antifreeze and aircraft deicing fluids Consumer products Deodorants, shampoos & cosmetics Manufacturing Byproduct of polyethylene terephthalate (PET) plastic Purifying agent in the manufacturing of pharmaceuticals 1,4-Dioxane residues may be present in food Manufactured food additives, food packaging materials or food crops treated with pesticides containing 1,4-Dioxane 1,4-DIOXANE 9

10. Potential sources Wastewater discharge Unintended spills, leaks Historical solvent disposal practices Group B2 (probable human) carcinogen Acute (short term) exposure in humans (via inhalation): vertigo, drowsiness, headache, anorexia and irritation of the eyes, nose, throat and lungs Chronic (long term) exposure in test animals (via drinking water): damage to liver, kidneys and gall bladder EPA 10 -6 cancer risk level of 0.35 μg/l SOURCES & HEALTH IMPACTS 10

11. DRINKING WATER GUIDELINES 11 State Guideline[1,4-D] (μg/l) CANotification level1 CODrinking water standard3.2 CTAction level3 MEMax exposure guideline4 MAGuideline0.3 NHProposed risk-based remediation value3 NYDrinking water standard50 SCDrinking water health advisory70 Source: Water Research Foundation, 2014 International guidelines vary between 0.1 and 50 μg/l

12. Dissolves readily into water Highly mobile, Recalcitrant to microbial degradation Very stable, not readily volatile in water Majority of treatment processes ineffective Conventional treatment Air stripping Activated carbon Reverse osmosis Ozone UV (not susceptible to direct photolysis) Advanced oxidation is effective TREATMENT OPTIONS 12

13. OZONE & UV ADVANCED OXIDATION 13

14. Generation & application of highly reactive free radicals Hydroxyl radical (OH◦) – most common Reacts rapidly and unselectively Most potent oxidant used in water treatment Destruction of a variety of recalcitrant contaminants Attractive option vs. other conventional oxidants Treatment of drinking water, water reuse, remediation ADVANCED OXIDATION 14 Cl2 (1.36 V) ClO2 (1.50 V) O3 (2.07 V) OH◦ (2.80 V)

15. Commonly applied AOPs Ozone (O 3 )/Hydrogen Peroxide (H 2 O 2 ) UV/H 2 O 2 Emerging AOPs UV/Chlorine (Cl 2 ) – only a few full-scale facilities in operation UV/Electrode – piloting experience Other AOPs (not commonly applied) O 3 /UV – very $$ (UV/H 2 O 2 or O 3 /H 2 O 2 typ. more economical) UV/TiO 2 Fe II /H 2 O 2 (Fenton’s reagent) ADVANCED OXIDATION PROCESSES 15

16. Taste & Odor 2-Methylisoborneol (MIB), Geosmin Algal Toxins Cylindrospermopsin, Anatoxin-a, Microcystin-LR, Saxitoxin Emerging Contaminants Volatile organic compounds (e.g. TCE, PCE) Semivolatile organic chemicals (e.g. NDMA) Synthetic organic chemicals (e.g. 1,4-Dioxane) Pesticides (e.g Metaldehyde) Endocrine disrupting compounds (EDC’s) Pharmaceuticals EFFECTIVE TREATMENT FOR A VARIETY OF COMPOUNDS 16

17. OH◦ scavengers - W ater constituents that compete for OH◦ with target contaminant and are typ. present in higher concentrations Carbonate (CO 3 2- ) and bicarbonate (HCO 3 - ): AOP is more effective at lower alkalinities Natural organic matter (NOM): AOP best applied downstream of solid-liquid separation following reduction of organic load Byproducts Complete oxidation of contaminants to carbon dioxide and water is possible (in theory), but not economical Breaking down complex organics to less innocuous and/or more biodegradable compounds Increase in assailable organic carbon (AOC) Other byproducts need to be considered WATER QUALITY CONSIDERATIONS COMMON TO ALL AOPS 17

18. OH◦ is produced via O 3 natural decomposition Self propagating chain reaction Dual oxidation via O 3 and OH◦ (limited) O 3 /H 2 O 2 AOP (AKA “Peroxone”) Reaction btw O 3 and NOM is preferred and instantaneous (i.e. O 3 demand) H 2 O 2 initiates decomposition cycle of remaining O 3 → OH◦ Potential benefits (vs. UV AOPs) Reduced energy and [H 2 O 2 ] requirements Reduced maintenance (vs. lamp replacements) Process challenges/considerations Byproduct formation (bromate) O 3 /H 2 O 2 ADVANCED OXIDATION 18

19. pH: neutral to basic (typ. 6.5 – 8) O 3 demand of water OH◦ scavenging demand Ratio of H 2 O 2 :O 3 is key H 2 O 2 is also an OH◦ scavenger Typ. goal is to optimize ratio to minimize both O 3 and H 2 O 2 residual Bromate formation Excess H 2 O 2 may be used in high bromide waters to limit reaction with O 3 and bromate formation (up to 90% H 2 O 2 residual) Treatment of H 2 O 2 residual (if present) Chlorine or activated carbon O 3 /H 2 O 2 TREATMENT R CONSIDERATIONS 19

20. Injection of oxidant upstream of UV H 2 O 2 or Cl 2 UV exposure results in formation of OH◦ and advance oxidation Potential benefits Reduced footprint and typ. lower capital as compared to O 3 (T&O) and O 3 AOP (recalcitrant contaminants) No bromate formation concerns (for H 2 O 2 ) Not impacted by typical water temperatures Some contaminants (NDMA) are susceptible to direct photolysis Increased treatment efficiency via dual destruction pathways (direct photolysis and advanced oxidation) UV ADVANCED OXIDATION 20

21. High power consumption / operating costs Require significantly more energy than UV disinfection systems (magnitude or more than required for disinfection) UV doses btw 500 to 4,000 mJ/cm 2 (vs. ≤ 40 mJ/cm 2 typ. used in disinfection) Duration of treatment is important for economics Seasonal T&O treatment – operated for disinfection majority of year Treatment of oxidant residual (for UV/H 2 O 2 ) Costs are highly variable and site specific (capital and O&M) Reactor-specific dose delivery efficiency Site-specific water quality UV AOP CHALLENGES 21

22. Scavenging demand Ratio of UV dose : oxidant dose Similar levels of treatment can be obtained by decreasing the oxidant dose with an increasing UV dose (or vice versa) Optimize balance between: Oxidant costs: chemical supply, storage & dosing equipment UV costs: equipment, operating power, maintenance Byproducts Nitrate formation for MP systems (wavelengths < 240 nm) Chlorinated by-products & bromate formation for UV/Cl 2 AOP Treatment of oxidant residual Required for UV/H 2 O 2, not typ. required for UV/Cl 2 UV AOP TREATMENT CONSIDERATIONS 22

23. Full-scale systems not validated At least not at the UV doses used for advanced oxidation Validation data may be used to confirm CFDi model accuracy UV manufacturers use a variety of techniques/approaches Testing (pilots and/or bench-scale) Determine relationship btw UV dose, oxidant dose & contaminant removal Water quality analyses: UVT, UVA scan, scavenging demand Results of UV AOP pilots not scalable to full-scale CFDi modeling Determine UV system design & power requirements to achieve required treatment based on test results UV AOP SIZING 23

24. Photochemical cleavage of H 2 O 2 → OH◦ Process limitations / considerations Poor absorbance of UV by H 2 O 2 High H 2 O 2 dose requirements (2 to 15 mg/l) High UV doses (i.e. increased energy) Inefficient reaction Only 5 – 10% of H 2 O 2 consumed in reaction Large H 2 O 2 residual downstream of UV that must be quenched (Cl 2, GAC, BAC) Not impacted by typical water pH Byproduct potential concerns limited to nitrate formation with MP systems UV/H 2 O 2 AOP 24

25. Production of OH◦ & chlorine radicals (Cl◦) Advantages over UV/H 2 O 2 AOP HOCl has higher UV absorbance and lower scavenging rate than H 2 O 2 Potential for increased OH◦ production efficiency, reduced oxidant dose & smaller UV system Small residual: 75-99% of Cl 2 consumed Cl 2 disinfection = no quenching required Process Limitations / Considerations Chlorine speciation is key: OCl - scavenging rate is 10 4 greater than HOCl = max pH of 6-6.5 Cl 2 dose limited (≤ 5 mg/l): Pitting of stainless steel Cl◦ byproducts: limited data (TTHMs, HAA, chlorite, chlorate?) UV/Cl 2 AOP 25

26. Developed by ETS Electrode replaces oxidation injection Anode: TDS → OCl - + HOCl, UV photolysis of HOCl → OH◦ + Cl◦ Cathode: H 2 O → H + + OH -, UV photolysis of OH -  OH◦ Advantages No oxidant injection or residual quenching Minimal power for electrode (20 W) Process Limitations/Considerations Anode: TDS ≥ 350 mg/l, pH ≤ 6.5, Cl◦ byproduct potential Cathode: Hydrogen off-gas Limited experience/applications UV/ELECTRODE AOP 26

27. CONCLUSIONS 27

28. 1,4-Dioxane has been reported by over 28% of N. Carolina PWSs participating in the UCMR 3 Concentrations ranging up to 190 times the MRL of 0.07 μg/l Conventional treatment, activated carbon, air stripping, RO as well as O 3 and UV alone are not effective for 1,4- Dioxane O 3 and UV AOPs provide effective treatment for 1,4- Dioxane as well as a variety of other recalcitrant contaminants Taste & Odor Algal Toxins VOCs, NDMA Pesticides, EDCs and pharmaceuticals CONCLUSIONS 28

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