320 likes | 429 Vues
Treatment of Emerging Environmental Contaminants In Water. NYC Watershed/Tifft Science & Technical Symposium September 19, 2013. Contaminants are now being detected regularly in the water supply
E N D
Treatment of Emerging Environmental Contaminants In Water NYC Watershed/Tifft Science & Technical Symposium September 19, 2013
Contaminants are now being detected regularly in the water supply Many regulators are now requiring routine testing of chemicals that were virtually unknown just a few years ago Growing awareness that the water supply is interconnected Supplies are tightening as population increases and water sources are more heavily tapped Unintentional water reuse is occurring “One city’s wastewater is another city’s drinking water” WATER QUALITY– GLOBAL TRENDS
OUR INTERCONNECTED WATER SUPPLY Sources of contaminants in our water supply: • Industrial discharge • Agricultural runoff • Chemical releases • Municipal wastewater Extraction Well Injection Well
WHAT IS UV-OXIDATION? It is the process of destroying trace organic contaminants in water by: UV-PhotolysisUV light alone breaks down the contaminant molecules UV-OxidationUV light plus hydrogen peroxide (H2O2) Hydrogen peroxide absorbs UV and produces hydroxyl radicals that oxidize contaminants
Chemical bonds arebroken by UV light UV-PHOTOLYSIS
Chemical bonds arebroken by hydroxyl radicals UV-OXIDATION Hydrogen peroxide Hydroxyl radical
HOW UV TREATS ENVIRONMENTAL CONTAMINANTS Simultaneous Processes Typically, UV-photolysis and UV-oxidation occur simultaneously: reaction time is milliseconds Most contaminants are broken down by a combination of both processes The relative contribution of either UV-photolysis and UV-oxidation varies by contaminant The UV energy output for both processes is sufficient to also provide microbial disinfection
EXAMPLES OF ECT CONTAMINANTS N-nitrosodimethylamine (NDMA)Industrial additive & disinfection byproduct 1,4-DioxaneIndustrial solvent Pesticides & HerbicidesAgricultural crop protection products Petroleum AdditivesIncluding MTBE Volatile Organics (TCE, PCE, Vinyl Chloride, etc.) Naphthalene and Phenols Pharmaceuticals & Personal Care ProductsIncludes potential endocrine disruptors
NDMA AND 1,4-DIOXANE BACKGROUND • No current federal regulations for either NDMA or 1,4-dioxane, however states have taken actions • 1,4-dioxane is a solvent stabilizer used to prevent solvent breakdown during degreasing operations • Conventional treatment technologies such as reverse osmosis (RO), coagulation/filtration, and carbon adsorption are ineffective
METHYL TERTIARY BUTYL ETHER (MTBE) - OVERVIEW • MTBE is a semi-volatile, chemically unreactive molecule • Highly soluble in water (increase with Temp decrease), • Sorbs poorly to soil grains, and has a low volatility (Treat air discharge?) • Persistent and mobile in groundwater • Break down to tert-butyl alcohol (TBA)
METHYL TERTIARY BUTYL ETHER (MTBE) - OVERVIEW Oxidation of MTBE generates TBA. TBA adsorbs readily to GAC/BAC Sources: leaking underground storage tanks, accidental spills of fuels, and releases from recreational vehicles in reservoirs. Regulated in NY (10 ppb), CA (13 ppb), NH (13 pp), PA (20 ppb), RI (40 ppb) and numerous others The USEPA has set non-enforceable drinking water advisory levels for MTBE of 20 ppb based on odor and 40 ppb based on taste Listed on the USEPA’s CCL and UCMR
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
LPHO PHOTOLYSIS OF HYDROGEN PEROXIDE Measured MP:LP = 2.8 The same number of hydroxyl radicals are produced with ~65% less power for LPHO vs. MP with this water quality
REACTOR DETAILS LPHO • Lamp power and number of reactors in operation automatically adjusted to minimize power • Reactors can be oriented 1-, 2-, or 3-high for small footprint • 250W LPHO lamp efficiently treating contaminants year round
Effluent Port Influent Port REACTOR DETAILS LPHO Two lamp bundles per chamber (one accessed from each end)
GROUNDWATER REMEDIATION INSTALLATION - STOCKTON, CA 200 GPM facility treating extracted groundwater Water is treated through air stripping, then UV-oxidation Contaminant of concern: 1,4-dioxane, TCE NDMA reduced from 150 ppb to less than 1 ppb TrojanUVPhox™, amalgam lamp lamp technology Full service hydrogen peroxide and delivery and maintenance
GROUNDWATER TREATMENT INSTALLATION – WATERLOO, ON Flow: 2378 gpm, 8ppm H2O2 dose Water is treated through Fe/Mn Filtration Contaminants of concern: 1,4-dioxane, TCE 1.3 Log reduction of 1,4 dioxane guarantee GAC for H2O2 quenching/redundancy (change out every 3 years, CL2 dosing back up) Full service hydrogen peroxide delivery and maintenance
LOCATION OF CALIFORNIA DOMESTIC WATER CO The California Domestic Treatment Facility
CONTAMINATION IN THE SAN GABRIEL VALLEY– BACKGROUND VOCs discovered in 1979 Plume defined, now traverses several “Operable Units” including the Baldwin Park OU 1997, NDMA, 1,4-dioxane and perchlorate detected Cal Domestic Plume map courtesy of EPA Region 9 Mailer, May 1999
THE TREATMENT PROCESS AT CAL DOMESTIC Flow Rate: 6.8 MGD (one train of two, =4,700gpm) 1. Ion Exchange 2. UV-Photolysis 3. Air Stripping 4. Chlorination (for residual in distribution system) Medium Pressure Rayox™ October 2001 to April 2005
THE TREATMENT PROCESS AT CAL DOMESTIC Flow Rate: 6.8 MGD (one train of two, =4,700gpm) 1. Ion Exchange 2. UV-Photolysis 3. Air Stripping 4. Chlorination (for residual in distribution system) Low Pressure High Output TrojanUVPhox™ April 2005 to Present
ENERGY USAGE (kWh) CAL DOMESTIC • ~5X more power used with MP solution vs. LPHO solution • Theory states that the lowest power ratio would be 3X • Increase to 5X from 3X due to enhanced optical & hydraulic efficiencies with LPHO reactor when compared to MP reactor
OTHER REMEDIATION PROJECTS El Monte, California – 0.072 MGD (50 gpm) Secor, Colorado – 0.029 MGD (20 gpm) Sunnyvale, California – 0.14 MGD (100 gpm) La Puente Valley County Water District, CA – 3.6 MGD California Domestic Water Company, CA – 14.5 MGD
Suffolk County Water Authority Pilot • Prove technology effectiveness on destruction of 1,4 dioxane and other VOCs • Existing GAC for removing residual peroxide (extends GAC life) • Water quality higher than initial design (99% UVT vs 95% UVT) • Scavenging demand lower = lower H2O2 dose • 1200 gpm Full scale system in design
Questions? Terry Keep ECT Sales Manager TrojanUV (519) 457-3400 tkeep@trojanuv.com www.trojanuv.com