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Taste and Odor Control at the Bloomington Water Treatment Plant

Taste and Odor Control at the Bloomington Water Treatment Plant. Rick Twait Superintendent of Water Purification, City of Bloomington Jill Mayes Water Lab Supervisor, City of Bloomington Dr. John O ’ Connor, PE Owner, H 2 O ’ C Engineering Tom O ’ Connor, PE Owner, H 2 O ’ C Engineering.

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Taste and Odor Control at the Bloomington Water Treatment Plant

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  1. Taste and Odor Controlat the BloomingtonWater Treatment Plant Rick Twait Superintendent of Water Purification, City of Bloomington Jill Mayes Water Lab Supervisor, City of Bloomington Dr. John O’Connor, PE Owner, H2O’C Engineering Tom O’Connor, PE Owner, H2O’C Engineering

  2. Evergreen Lake + Lake Bloomington 1971 (900 acres) 1929 (635 acres) Evaluation of Taste and Odor Control Methods for the Bloomington, IL Water Treatment System 29:1 70:1

  3. Lake and Watershed Management Destratifiers Lake monitoring • Algal monitoring • Volunteer Lake Monitoring Program (VLMP) Shoreline stabilization Tiles, streams, ponds; weekly sampling Wetlands study: nutrient management

  4. Lake Water Quality Concerns Algal blooms: tastes and odors oxygen depletion (anoxia) Agricultural drainage: nutrients, soil erosion pesticides, herbicides biological pathogens Development: construction, runoff waste discharges Lake Aging: shoreline erosion sediment accumulation

  5. Bloomington Water Treatment Plant Coagulation Ferric Sulfate + Cationic Polymer Lime Softening Lime Sludge Lagoons Stabilization Recarbonation, Polyphosphate Sand Filtration Granular Activated Carbon caps

  6. Evergreen Lake - Geosmin/MIB vs. Depth

  7. Geosmin/MIB - Winter 2004

  8. Lime Sludge Storage Lagoons Supernatant reclaimed to WTP influent

  9. Geosmin/MIB Nov 2004 - Jan 2006 < 10% of plant influent reclaimed from lagoons control/eliminate lagoon return water

  10. Water Plant Operational Responsesfor Taste and Odor Control • increased dosage of cationic polymer (coagulant) • reduction in filtration rates to maximize GAC EBCT • extend filter run times to increase biodegradation • initiation of maximum PAC feed prior to softeners • cease prechlorination to avoid lysis of cells • evaluation of geosmin/MIB reductions through plant • microscopic analyses to identify algal populations

  11. Microscopic Process EvaluationsWeekly Series: from Lakes & Lagoon to Finished Water Tap

  12. Geosmin/MIB Monitoring Most Geosmin/MIB removal occurs during filtration

  13. Removal of Geosmin/MIB by Filtration

  14. Overall Plant Removal of Geosmin

  15. Bloomington, Illinois GAC Filter Caps 24-inch deep filter cap replaced with virgin GAC after two years

  16. Virgin versus Microbially-Colonized GAC Granules

  17. Stalked Bacteria on Granular Activated Carbon

  18. Bloomington WTP LaboratoryColumn Studies of Removal of Geosmin by GAC Assessment of Factors Affecting GAC Removal of Geosmin GAC Age/Condition: virgin GAC (minimal microbial growth) GAC in service for one-year GAC in service for two years Contact Time: GAC in service for two years at twice EBCT Temperature: winter vs. summer operating conditions

  19. GAC Column StudiesGeosmin-spiked column influentGAC columns (4)Geosmin, TOC sample bottlesLuminescent DO Meter(oxygen depletion)

  20. Geosmin-spiked GAC Column Influent

  21. GAC Columns Fresh (Virgin) One-Year-Old Two-Year-Old Two-Year-Old @ twice EBCT

  22. Removal of Geosmin on GAC

  23. Percent Removal of Geosmin

  24. Effect of Temperature on Geosmin Removal

  25. Turbidity of GAC Rinse Water

  26. Microscopic Examination of GAC Rinse Water

  27. Micrograph: Virgin Carbon Extract 400x

  28. Micrograph: One-Year-Old GAC 400x

  29. Micrograph: Two-Year-Old GAC 400x

  30. Micrograph: Two-Year-Old GAC 400x

  31. Additional Testing Aeration stripping of volatile compounds Ozonation stripping plus oxidation Chemical Oxidation potassium permanganate, chlorine dioxide, Fenton’s reagent, hydrogen peroxide + ultraviolet light

  32. Ozonation reduces geosmin, but imparts ozonous odor Aeration 29% geosmin reduction due to aeration alone

  33. Application of Potassium Permanganate, Sodium Chlorite plus Sodium Hypochlorite,and Fenton’s Reagent failed to noticeably reduce earthy-musty odors

  34. Removal of Geosmin by UV-Peroxide

  35. Removal of Geosmin by UV-Peroxide Influent Geosmin: 350 ng/l H2O2 dosage: 30 mg/l UV dosage: 38 J/cm2 Effluent Geosmin: ND

  36. Conclusion Predict monitor nutrients, algal populations, dissolved oxygen, temperature, microcystins, blue-green pigment, UV254 , and TASTE THE WATER Pre-empt lake destratification, avoid lagoon recycle (discharge permit pending), avoid pre-oxidation Remove GAC adsorption / biodegradation

  37. Acknowledgements Ron Stanley, lab technician and the Staff of the Bloomington Water Treatment Plant

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