THE USE OF UV/PEROXIDE FOR TREATING ALGAL DERIVED CONTAMINANTS IN DRINKING WATER Terry Keep AWWA NYS Tifft Water Supply Symposium September 21, 2017
WATER STRESS IN AN INTERCONNECTED WATER SUPPLY Sources of contaminants in our water supply: - Industrial discharge - Agricultural runoff - Chemical releases - Municipal Wastewater Injection Well Extraction Well Nutrients increase in Algae Blooms Taste & Odour, Algal Toxins 2
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 Compounds Seasonal occurrences of MIB, geosmin and others Algal Toxins Chronic and acute effects from cyanobacteria-derived toxins 3
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 4
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 5
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 6
UV-PHOTOLYSIS Chemical bonds are broken by UV light 7
UV-OXIDATION Hydrogen peroxide Hydroxyl radical Chemical bonds are broken by hydroxyl radicals 8
UV-Photolysis/UV-Oxidation Contribution to Total Contaminant Reduction (relative to NDMA) CONTAMINANT DESTRUCTION BALANCE 6.0 5.0 UV + H2O2 UV Photolysis 4.0 3.0 2.0 1.0 0.0 NDMA Atrazine Geosmin Microcystin-LR 9
ALGAL TOXINS OXIDIZED MORE EASILY THAN MIB 10
APPLICATION OF UV ADVANCED OXIDATION FOR TASTE & ODOUR / ALGAL TOXIN TREATMENT
DUAL-MODE OPERATION 12
geosmin 2- methylisoborneol (2-MIB) dimethyl trisulfide cis, 4-heptanal trans, trans, 2,4- heptadienal cis-3-hexenyl acetate Percent Removal UV-OXIDATION A RANGE OF T&O COMPOUNDS 100.0% 90.0% 80.0% Performance Target 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Earthy Musty Swampy Fishy Rancid fish Grassy (sweet) 13
COMPOUNDS GENERATED BY SOME CYANOBACTERIA Aesthetics: T&O cmpds Public Health: Cyanotoxins Geosmin [Geosmin] have been measured > 3000 ng/l Microcystin-LR (MC-LR) [MC]~1800ug/L meas drng bloom Cylindrospermopsin (CYN) 2-Methylisoborneol (MIB) GSM and MIB can be detected by sensitive individual down to 4 ng/l (ppt) 14
SYSTEM SIZING
SIZING FACTORS FOR ECT SYSTEMS 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
UV-PHOTOLYSIS AND UV-OXIDATION KINETICS The overall kinetic equation describing the photolytic and UV/H2O2 Hydrogen peroxide photo-oxidative reactions of a micropollutant C is: Hydroxyl radical d[ C] dt k[ C] C 300 200 N 0 V F S F C k C V ( k C [ C]2 H [ C] k 2 O H 2 2 300 200 O 2 [ H N 2 0 O 2 F S ] F H 2 O k 2 S [ S] UV-Photolysis UV-Oxidation Where: FC, FS, FH 2O2 N 0 k 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
CASE STUDIES
Aqua PA s Neshaminy WTP, Pennsylvania Hatch Mott MacDonald Presented at New Jersey, Ohio and Pennsylvania Annual AWWA Conferences 2010 Researchers Evaluated the following Treatment Technologies: PAC GAC Ozone UV AOP 19
Aqua PA s Neshaminy WTP, Pennsylvania Hatch 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
Estimates were based on a PAC dose of 30 mg/l and a 90-day taste and odor period 21
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. 22
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. 23
UV Reactor Chamber Cooling Water Outlet Cooling Water Inlet
UV Reactor Chamber Cooling Water Inlet UV Reactor UV Reactor
Alliance Ohio T&O: Planning and Engineering Approach to the Final Design o o o o UV Oxidation System Feasibility Study UV Oxidation System Procurement UV Oxidation System Final Design Documents 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
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 30
REGIONAL MUNICIPALITY OF WEST ELGIN, ON 31
PERFORMANCE RESULTS WEST ELGIN, ONTARIO (APRIL 2009) 32
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) 33
QUESTIONS? THANK YOU Terry Keep Trojan Technologies (519) 457-3400 tkeep@trojanuv.com 34