Ultraviolet Disinfection for Municipal Drinking Water

Transcription

1 Ultraviolet Disinfection for Municipal Drinking Water WATERCON 2012 Springfield, IL March 21, 2012 Patrick Bollman, P.E. Municipal Operations Manager Engineered Treatment Systems (ETS)

2 Program Outline UV Fundamentals Equipment Selection Drinking Water Requirements and Validation Maintenance Advanced Oxidation Process (AOP)

3 UV Fundamentals

4 UV History Year Event 1903 Fluorescent mercury vapor lamp invented 1917 Drinking water in Europe 1920s Medium pressure UV lamp invented 1970s Drinking water expansion in Europe 1980s Expansion industrial (world); drinking water (Europe) 1990s Expansion wastewater (US) 2000 Used against Crypto and Giardia 2001 Wastewater reuse 2006 USEPA drinking water guidance manual

5 What Does UV Do in Water? Disinfection of microorganisms photons absorbed by DNA leads to inactivation (inability to replicate) by dimerization of thymine base units in the DNA Photolysis photons of UV light absorbed by molecules such as NDMA or hydrogen peroxide lead to chemical change, resulting in their destruction

6 Electromagnetic Spectrum Primary Disinfection Range (UVC) = 200 to 280 nm

7 Microbial Response to UV Healthy DNA DNA after UV

8 Low Pressure (40W 80W) UV Lamp Types Low Pressure High Output and Amalgam (100W 1000W) Medium Pressure (400W 25000W)

9 Lamp Comparison Low Pressure Low Pressure High Output/Amalgam Medium Pressure Lamp Power (W) 40 to to to UVC Efficiency (%) 35 to to to 15 Lamp Life (hrs) 8,000 to 12,000 8,000 to 12,000 3,000 to 8,000 Internal Gas Pressure (Torr) 10-2 to to to 10 4 Lamp Surface Temperature (F) Wavelengths Monochromatic Monochromatic Polychromatic Efficiency vs. Water Temp. (F) 60 > 60 Any

10 Equipment Selection

11 Required Parameters Flowrate Water Quality Required Disinfection (dose/log reduction) Plant Hydraulics

12 Flowrate and Water Quality Minimum Flow Average Flow Peak Flow Transmittance (T10%) Iron and Manganese Concentrations

13 UV Transmittance Measurement of the amount of light that penetrates through the water Tested with spectrophotometer (deuterium lamp) in a quartz cuvette UV absorbed in fluid UV % Deuterium light source 10 mm wide sample cell UV sensor

14 Expected UV Transmittance Values Water Source Transmittance (T10%) Ultrapure Water 100% Distilled Water 98% Drinking Water 80-95% Membrane (WW) 70-80% Secondary Filtered 65-70% Secondary Unfiltered 50-65% Meat Brine, Soft Drinks 0%

15 Iron and Manganese Fouling

16 Drinking Water Requirements and Validation

17 UV Design Guidance Manual

18 Equipment Validation UV units for drinking water must be validated by third party (current validation sites include DVGW (Germany), HDR/Hydroqual (Johnstown, NY), Carollo Engineers (Portland, OR), or onsite (not recommended alternative)) Equipment is validated under a range of operating conditions: flow, UVT, and dose (utilizing various nonpathogenic organisms) Full scale unit (scaling of reactors is not permitted)

19 UV Design Guidance Manual Inactivation log credit based on delivered UV dose relative to required UV dose tables Delivered UV dose must be demonstrated by a reactor validation test and ongoing monitoring Validation test verifies operating conditions under which reactor can deliver the required UV dose Microbial challenge test of full-scale UV reactor MS2 (US), T1 (US), T7 (US), and B.Subtilus (Germany) Operating conditions include flowrate, UV intensity measured by sensors, UV absorbance/transmittance, inlet/outlet conditions Monitoring demonstrates that UV reactor operates within validated conditions during routine use

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21 Regulatory Summary Long Term 2 Enhanced Surface Water Treatment Rule Cryptosporidium E. coli Stage 2 Disinfectants and Disinfection By Products Rule DBPR is one part of the Stage 2 Microbial and Disinfection Byproducts rules (M-DBP) Monitoring requirements for trihalomethanes (TTHM) and haloacetic acids (HAA5)

22 LT2ESWTR Log Inactivation Pathogens Log Inactivation* Crypto Giardia Virus * UV dose required does not include validation, aging, fouling, etc., factors. Actual provided dose from manufacturers will be greater than numbers above. Fecal coliform = 1-log reduction at approximately 5 mj/cm2.

23 LT2ESWTR Compliance Timeline System Size (Population Served) ,000+ Crypto Monitoring Treatment Installed April 1, ,000 to 99,999 Crypto Monitoring Treatment Installed Oct. 1, ,000 to 49,999 Crypto Monitoring Treatment Installed Oct. 1, 2013 <10,000 E. Coli & Crypto Monitoring Treatment Oct.1, 2014

24 LT2ESWTR Bin Classification Filtered System Results will place in one of four bins based on monitoring results (concentration of crypto) Bins 2 4 require additional crypto treatment (including UV) Unfiltered System Crypto inactivation requirement either 2 or 3 log reduction Two disinfectants are required, one of must be UV, O 3, or ClO 2

25 Filtered System Bin Classification Crypto Concentration (oocycsts/l) Bin Level < to to > 3.0 4

26 LT2ESWTR Monitoring Systems must monitor UV reactors to demonstrate operation within validated conditions Monitoring must include UV intensity, flowrate, lamp outage and other parameters as required by the State Systems must verify UV sensor calibration and recalibrate using a State-approved protocol Systems must report each month the percentage of water not treated by UV reactors operating within validated conditions for the required dose (must treat >95%)

27 LT2ESWTR Monitoring Parameter Monitoring Frequency Recording Frequency Power Draw Continuous Every 4 hours Water Temperature Continuous Daily UV Lamp On/Off Cycles Continuous Weekly (total cycles/week) Turbidity Daily Weekly ph, iron, calcium, alkalinity, Hardness, ORP Weekly Weekly UVT Analyzer Calibration Weekly Weekly Equipment Age Monthly Weekly Flowmeter Calibration Monthly Weekly

28 Maintenance

29 Maintenance Lamps 8,000 to 12,000 hours Quartz sleeves three to five years Quartz sleeve o-rings replace with quartz sleeves Wiper rings 1,000 to 8,000 wipe cycles (one to two years) CWT 10+ years Ballasts one to five years UV intensity sensors one to five years Manually clean sleeves varies on automatic wiper and water quality

30 AOP

31 Advanced Oxidation Process AOP Usually involve the generation of hydroxyl radicals ( OH ) Called advanced because the overall reactions of pollutants are the same as slow degradation reactions occurring in the environment, but are highly accelerated The OH radicals react with organic pollutants to initiate a series of oxidative degradation reactions The overall process often leads to mineralization (i.e., conversion to CO 2, H 2 O and mineral acids) of the pollutants

32 Emerging Contaminants Often man made Conventional WWTP cannot remove Prison waste streams - Reuse Long lasting Present in most surface waters EPA debate regarding cost benefit All high molecular mass - rate constants permit AOP EE/O to quantify removal rates

33 PPCPs PPCPs include: Sun screen products Prescription and over-the-counter therapeutic drugs Diagnostic agents Veterinary drugs Fragrances Cosmetics Nutraceuticals (vitamins) Sources of PPCPs: Agribusiness Hospital residues Human activity Pharmaceutical manufacturing residues (well defined and controlled) Illicit drugs Veterinary drug use (antibiotics and steroids)

34 Summary UV is a known disinfection process Different types of UV lamps are available Certain parameters must be provided to manufacturers to accurately size a system DW systems must be validated by a 3 rd party UV systems will require maintenance and monitoring UV can be used in advanced oxidation applications (taste and odor, PPCPs, etc.)

35 Questions???? Patrick Bollman, P.E. Municipal Operations Manager Engineered Treatment Systems W9654 Beaverland Pkwy. Beaver Dam, WI Phone: Fax: Web: