Use of Ozone for Disinfection and EDC Removal at CCWRD

1. Use of Ozone for Disinfectionand EDC Removal at CCWRD Doug Drury, Ph.D. Deputy General Manager Clark County Water Reclamation District Shane Snyder, Ph.D. R&D Project Manager Southern Nevada Water Authority

2. What Happens in Vegas Stay in Vegas Doesn’t

3. Nevada Dischargers • Clark County Water Reclamation District discharges ~100 MGD • Largest discharger in the State of Nevada • Largest discharger to the Colorado River

4. Lake Mead at ~1,140 Feet Elevation Future Drinking Water Intake CCWRD Treatment Plant Existing Drinking Water Intakes Las Vegas Wash New Wastewater Diffuser Present Lake Mead Surface Elevation ~1,111 Feet

6. Reach 0 (CNLV) Systems Conveyance & Operations Program (SCOP) Reach 1 Reach 2 Reach 4 River Mountain Tunnel #3 Reach 3 COH Pump Sta. and Force Main Hydropower Reach 5 Outfall Diffuser

9. Male Bass Across Region Found to Be Bearing EggsPollution Concerns Arise In Drinking-Water Source By David A. FahrentholdWashington Post Staff WriterWednesday, September 6, 2006; A01 Abnormally developed fish, possessing both male and female characteristics, have been discovered in the Potomac River in the District and in tributaries across the region, federal scientists say -- raising alarms that the river is tainted by pollution that drives hormone systems haywire. The fish, smallmouth and largemouth bass, are naturally males but for some reason are developing immature eggs inside their sex organs. Their discovery at such widely spread sites, including one just upstream from the Woodrow Wilson Bridge, seems to show that the Potomac's problem with "intersex" fish extends far beyond the West Virginia stream where they were first found in 2003. The cause of the abnormalities is unknown, but scientists suspect a class of waterborne contaminants that can confuse animals' growth and reproductive systems. These pollutants are poorly understood, however, leaving many observers with questions about what the problems in fish mean for the Potomac and the millions of people who take their tap water from it.

15. Objectives • Expansion of current facility • 110 to 150 MGD • Opportune time to utilize state of the art technology • Membranes for phosphorus removal • Ozone for disinfection • Membranes for: • Bacterial disinfection • P removal TMDL of 174#/day or ~0.2 mg/L • Ozone demand reduction • Ozone for: • Viral disinfection • Existing fecal coliform limit of 200#/100ML • Future designs: • Wet weather fecal of 200#/100ML • Dry weather total coliform of 2.2#/100ML • Emerging contaminant removal

16. Objectives (cont’d) • Use bench-scale evaluations for initial feasibility • Engineering analysis to estimate Capital and O&M costs • Compare U.V. and ozone disinfection

17. Why Ozone? • Powerful disinfectant • No residual (compared to chlorine) • Stronger oxidant (compared chlorine/U.V.) • Three ozone plants in Southern Nevada • AMS 600 MGD drinking water • River Mountains 300 MGD drinking water • Big Bend (Laughlin) 20 MGD drinking water • Ozone proven technology for disinfection & contaminant removal

18. SNWA Treatment Studies

19. SNWA EDC Research • 1997: Initial screening of LV Wash & Lake • Estrogen compounds detected in Wash & Bay • No estrogens detected in drinking water • First detection of pharmaceuticals • 1998: Fish caged in Lake Mead • Subtle differences in fish from LV Bay, but not dramatic as seen in USGS studies • 2000: DOD funded study of fish • Small differences among LV Bay & Overton • Perchlorate not related to EDC effects in fish

20. Southern Nevada WWTPs 2003 (ng/L) CCWRD WWTP#2 WWTP#3

21. UV 40mJ/cm2

22. Chlorine 3.5 mg/L 24 hr

24. <30% Removal 30-70% Removal >70% Removal Musk Ketone Meprobamate Testosterone TCEP Atrazine Progesterone Iopromide Androstenedione Estriol Ethynylestradiol Estrone Ozone 2.5 mg/L Estradiol Erythromycin-H2O Sulfamethoxazole Triclosan Trimethoprim Naproxen Diclofenac Ibuprofen Hydrocodone Acetaminophen Carbamazepine Dilantin Diazepam Caffeine Fluoxetine DEET Metolachlor Galaxolide Pentoxifylline Gemfibrozil

25. Naproxen Triclosan 17β Estradiol Sulfamethoxazole Gemfibrozil Easy to Oxidize

26. Iopromide TCEP Musk Ketone Meprobamate Atrazine Difficult to Oxidize

28. 6 CCWRD Bench Ozone Decay 5 O3=6.9 mg/L 4 O3=6.0 mg/L O3=4.3 mg/L O3=1.8 mg/L 3 Dissolved Ozone Residual (mg/L) 2 1 0 0 5 10 15 20 25 30 Contact Time (min)

30. CCWRD Filtered Effluent Average Concentrations

31. CCWRD Filtered Effluent Average Concentrations

32. CCWRD Filtered Effluent Compounds Removed to <MRL- With Ozone > 3mg/L

33. Before Ozonation After Ozonation

34. Ozone Removal Summary

35. Bromate Formation Drinking Water MCL

36. Process Flow Schemes • Clark County Water Reclamation District’s present process flow scheme includes: sand filters for phosphorus removal and U.V. for disinfection • With new scheme: • Membranes replace sand filters for phosphorus removal • Ozone replaces U.V. for disinfection • Possible advantages with new process scheme: • Reclamation disinfection requirements could be met • “90% removal of 90% of EDCs” • Possible disadvantages: • Safety • Possible formation of disinfection by-products such as Bromates

37. Preliminary Engineering Cost Estimates • Capital • Membranes and ozone about 28% higher than media filtration and U.V. • O&M • Ozone and U.V. are about the same for reclamation disinfection • Membranes about 24% higher than the media filtration costs

38. Equipment Manufacturer’s Qualified • Membranes • Pre-qualified 3 membrane manufacturers: • GE’s Zenon 500D submerged membranes • U.S. Filter’s submerged and pressure filters • Pall’s pressure filters • Ozone • Pre-qualified 3 ozone manufacturers: • Ozonia • Wedeco, Inc. • Fuji Electric Corp. of America

39. Pre-purchasing for 30 MGD Pilot Membrane/Ozonation Equipment • Used an evaluated bid process to calculate the present worth for determining the low bidder • Ozonia was low bidder for ozonation • A purchase order was issued July 17, 2007 • Price of 30 MGD ozone equipment is $3,205,000 • Zenon was low bidder for membranes • Price of 30 MGD of membranes is $9,830,000

40. Design Engineer’s Liability? • Strange questions from 3 different engineering firms working on 3 different membrane ozone projects: • “Do you know that ozone by itself cannot meet reclamation disinfection requirements?” • “Do you have an EDC requirement in your permit?” • “Do you know that ozone will not remove all EDCs?” • “Do you know that disinfection with ozone is considerably more expensive than other alternatives?” • “Do you know that unknown disinfection by-products may be formed?”

41. Summary • Southern Nevada has extensive history & expertise in ozone technology; 920 MGD in 3 different water treatment plants • U.V. is not oxidative at disinfection dose • Ozone provides disinfection & oxidation • Neither U.V. nor Ozone have residual issues • Costs for Ozone and U.V. are comparable for disinfection in reuse application • Estimated costs for Membranes/Ozone about 24-28% higher than present media filters/U.V. disinfection

42. Conclusions • Trace contaminants are ubiquitous • The vast majority of organic contaminants are removed by ozone • Contact times from pilot would be realistic • ~ 8-20 min contact time for ozone • Ozone has byproducts! Must look for them.

43. Future? • Presently designing 30 MGD “greenfield” Membrane/Ozone expansion • On-line Fall 2008 • Actual full scale cost effectiveness will be evaluated • U.V. versus Ozone • Membranes versus Filter • Will bromate be a major issue with ozone?

44. Questions Doug Drury, Ph.D. ddrury@cleanwaterteam.com Shane Snyder, Ph.D. shane.snyder@snwa.com