taste and odor control at the bloomington water treatment plant rick twait superintendent of water...
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Taste and Odor ControlTaste and Odor Controlat the Bloomingtonat the Bloomington
Water Treatment PlantWater Treatment Plant
Rick TwaitSuperintendent of Water Purification, City of Bloomington
Jill MayesWater Lab Supervisor, City of Bloomington
Dr. John O’Connor, PEOwner, H2O’C Engineering
Tom O’Connor, PEOwner, H2O’C Engineering
Evergreen Lake + Lake Bloomington1971 (900 acres) 1929 (635 acres)
70:1
29:1
Evaluation of Taste Evaluation of Taste and Odor Control and Odor Control Methods for the Methods for the Bloomington, IL Bloomington, IL
Water Treatment Water Treatment SystemSystem
Lake and Watershed ManagementLake and Watershed Management
Destratifiers
Lake monitoring
• Algal monitoring
• Volunteer Lake Monitoring Program (VLMP)
Shoreline stabilization
Tiles, streams, ponds; weekly sampling
Wetlands study: nutrient management
Lake Water Quality ConcernsLake 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
Bloomington Water Treatment PlantBloomington Water Treatment Plant
Coagulation Ferric Sulfate + Cationic Polymer
Lime Softening Lime Sludge Lagoons
Stabilization Recarbonation, Polyphosphate
Sand Filtration Granular Activated Carbon caps
Evergreen Lake - Geosmin/MIB vs. DepthEvergreen Lake - Geosmin/MIB vs. Depth
Geosmin/MIB - Winter 2004 Geosmin/MIB - Winter 2004
Lime Sludge Storage LagoonsLime Sludge Storage Lagoons
Supernatant reclaimed to WTP influent
Geosmin/MIB Geosmin/MIB
< 10% of plant influent
reclaimed from lagoons
control/eliminate lagoon return water
Nov 2004 - Jan 2006
Water Plant Operational ResponsesWater Plant Operational Responsesfor Taste and Odor Controlfor 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
Microscopic Microscopic Process Process
EvaluationsEvaluations
Weekly Series: from Lakes & Lagoon to Finished Water Tap
Most Geosmin/MIB removal occurs during filtration
Geosmin/MIB MonitoringGeosmin/MIB Monitoring
Removal of Geosmin/MIB by FiltrationRemoval of Geosmin/MIB by Filtration
Overall Plant Removal of GeosminOverall Plant Removal of Geosmin
Bloomington, IllinoisBloomington, IllinoisGAC Filter Caps GAC Filter Caps
24-inch deep filter cap replaced with virgin GAC after two years
Virgin versus Virgin versus Microbially-Microbially-Colonized Colonized
GAC GranulesGAC Granules
Stalked Bacteria on Granular Activated CarbonStalked Bacteria on Granular Activated Carbon
Bloomington WTP LaboratoryBloomington WTP LaboratoryColumn Studies of Removal of Geosmin by GACColumn 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
GAC Column StudiesGAC Column Studies
Geosmin-spiked column influent
GAC columns (4)
Geosmin, TOC sample bottles
Luminescent DO Meter
(oxygen depletion)
Geosmin-spiked Geosmin-spiked GAC Column InfluentGAC Column Influent
GAC ColumnsGAC Columns
1. Fresh (Virgin)
2. One-Year-Old
3. Two-Year-Old
4. Two-Year-Old @ twice EBCT
Removal of Geosmin on GACRemoval of Geosmin on GAC
Percent Removal of GeosminPercent Removal of Geosmin
Effect of Temperature on Geosmin RemovalEffect of Temperature on Geosmin Removal
Turbidity Turbidity of GAC of GAC Rinse Rinse WaterWater
Microscopic Examination ofMicroscopic Examination ofGAC Rinse Water GAC Rinse Water
Micrograph: Virgin Carbon ExtractMicrograph: Virgin Carbon Extract
400x400x
Micrograph: One-Year-Old GACMicrograph: One-Year-Old GAC
400x400x
Micrograph: Two-Year-Old GACMicrograph: Two-Year-Old GAC
400x400x
Micrograph: Two-Year-Old GACMicrograph: Two-Year-Old GAC
400x400x
Additional Testing Additional Testing
Aeration stripping of volatile compounds
Ozonation stripping plus oxidation
Chemical Oxidation
potassium permanganate,
chlorine dioxide,
Fenton’s reagent,
hydrogen peroxide + ultraviolet light
OzonationOzonationreduces geosmin, but
imparts ozonous odor
AerationAeration 29% geosmin reduction
due to aeration alone
Application of Potassium Permanganate,
Sodium Chlorite plus Sodium Hypochlorite,
and Fenton’s Reagent failed to noticeably
reduce earthy-musty odors
Removal of Geosmin by UV-PeroxideRemoval of Geosmin by UV-Peroxide
Influent Geosmin: 350 ng/l
H2O2 dosage: 30 mg/l
UV dosage: 38 J/cm2
Effluent Geosmin: ND
Removal of Removal of Geosmin by Geosmin by UV-PeroxideUV-Peroxide
ConclusionConclusion
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
AcknowledgementsAcknowledgements
Ron Stanley, lab technician
and the
Staff of the Bloomington Water Treatment Plant