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Toledo Waterways Initiative and 185 mgd HRT Facility Wet

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Toledo Waterways Initiative and 185 mgd HRT Facility Wet Weather Partnership CSO Workshop Chicago, IL Larry Jaworski - Black & Veatch F. Chris Middlebrough City ... – PowerPoint PPT presentation

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Title: Toledo Waterways Initiative and 185 mgd HRT Facility Wet


1
Toledo Waterways Initiative and 185 mgd HRT
FacilityWet Weather Partnership CSO
WorkshopChicago, IL
  • Larry Jaworski - Black Veatch
  • F. Chris Middlebrough City of Toledo, OH
  • Carol L. Hufnagel Tetra Tech

2
Background
  • Late 80s Early 90s Three CSO storage
    tunnels constructed.
  • October 1991 Original US/OEPA vs. Toledo
    lawsuit.
  • July 2002 Toledo voters approve ordinance to
    settle lawsuit.
  • Consent decree.
  • Start of Toledo Waterways Initiative.

3
Consent Decree Requirements
  • Discharge from Outfall 002 allowed only when flow
    exceeds 400 MGD
  • Activated sludge treatment of all flows up to 195
    MGD
  • 60 MG EQ basin (reduced to 25 MG pending EPA
    approval) dewatered flows must receive activated
    sludge treatment
  • 185 MGD high rate clarification facilities may
    discharge only when flow exceeds 195 MGD EQ
    basin is full
  • Prohibited return of wet weather treatment solids
    to main plant headworks

4
Bay View WWTP Flows
  • Toledo, OH sewer system is 30 combined
  • Bay View WWTP flows
  • 45 MGD dry weather
  • 70 MGD average annual
  • 130 MGD peak month
  • 400 MGD peak hour
  • Maximum flow through secondary treatment is
    approximately 195 MGD

5
HRT Milestones
  • February 2003 - Pilot Test Completed
  • HRT - DensaDeg vs. Actiflo
  • UV Disinfection - Medium Pressure vs. LPHO
  • 2005 Construction Started
  • October 2006 Performance Testing of HRT
  • 2007 Begin Two-Year Effectiveness Study

6
HRT Evaluation Factors
  • Discharge Requirements
  • Frequency of Use/Chemical Usage
  • Pretreatment Needs
  • Pumping
  • Fine Screening
  • Grit Removal
  • Odor Control
  • Startup Shutdown Requirements
  • Solids Handling Requirements
  • Flexibility to Use for Primary Tertiary
    Treatment

7
HRT Pilot Test
  • Actiflo - Kruger (Veolia Water)
  • DensaDeg - IDI

8
Actiflo DesignConsiderations
  • Fine Screening (lt 1/4 inch openings)
  • f (Hydrocyclone opening)
  • Requires Grit Removal
  • Thin Sludge (lt0.5 solids)
  • Volume 2 to 3 of Influent Flow
  • ( capacity of recirculation
  • pumps)
  • Media Recirculation
  • Cleaning System

9
DensaDeg Design Considerations
  • Less Consistent Performance Due to Ballast Media
    (Sludge) Variability
  • Fine Screening (lt 1/2 inch openings)
  • Concentrated Sludge (3 to 4 solids)
  • Slower Startup Due to Reliance on Sludge
    Recirculation
  • Potentially deeper settling compartment than
    Actiflo

10
HRT Intermittent Operation Issues
  • Dry process startup time required to establish
    process equilibrium
  • Handling off-spec effluent
  • Bringing parallel units on-line
  • Maintaining a standby operational mode
  • necessary for Actiflo
  • Dewatering to prevent nuisance conditions

11
Other Uses for HRT
  • Primary Treatment
  • Derate to about 1/3 to ½ of Wet Weather Treatment
    Capacity
  • Uses less Ferric Chloride than for Wet Weather
    Treatment
  • Densadeg better than Actiflo due to solids
    thickening feature
  • Dry Weather Tertiary Treatment
  • Lowers TSS phosphorus concentrations
  • Improves chances of meeting 7-day limits when
    averaged with wet days

12
HRT Costs
  • Capital costs very close to the same in most
    cases
  • Smaller footprint for Actiflo due to higher
    loading rates
  • Less pretreatment required for DensaDeg
  • If solids cannot be returned to plant influent,
    solids handling costs are lower for DensaDeg
  • OM costs slightly less for DensaDeg due mostly
    to lower pretreatment requirements

13
Reasons for Selection of DensaDeg
  • No additional sludge processing facilities
    required
  • No additional fine screening facilities required,
    increasing amount of screening equipment to be
    maintained and screenings to be handled
  • Rapid startup is not an issue
  • Equipment is the same as existing equipment to
    service and maintain
  • No need to maintain a standby mode
  • No microsand and related maintenance and
    housekeeping issues

14
High Rate Clarification
EQ BASIN
UP TO 400 MGD
27 MGD
UP TO 205 MGD
SCREENING GRIT REMOVAL
SECONDARY CLARIFIERS
BAY VIEW PUMP STATION
CHLORINE CONTACT BASIN
232 MGD
CHLORINE CONTACT REAERATION
AERATION BASINS
168 MGD
PRIMARY CLARIFIERS
UP TO 195 MGD
PRIMARY CLARIFIERS
GRIT REMOVAL
SKIMMINGS REMOVAL
UP TO 400 MGD
EFFLUENT PUMPING
NEW WET WEATHER FACILITIES
15
Bay View WWTP Layout
16
Toledo, OhioBay View Wastewater Treatment Plant
Reaeration Chlorination
Main WWTP
XS Flow
DensaDeg
EQ Basin
Vortex Grit Removal Screening (1 sewer)
17
Toledo, OH DensaDeg Layout
18
Toledo, OH DensaDeg HRT
19
HRT Pipe Gallery Sludge Pumps
20
HRT and EQ Basin
21
HRT Treatment Results
  • Performance testing results
  • Effluent TSS 7 to 38 mg/L with average of 25
    mg/L.
  • TSS removal averaged approximately 80.
  • Effluent CBOD 22 to 177 mg/L with average of 52
    mg/L.
  • CBOD removal averaged approximately 55.
  • Mixture of dry and wet weather conditions during
    performance testing.
  • 2-year effectiveness study ongoing thru 2008.

22
First 6 Months of 2-year Effectiveness Study
23
Wet Weather Treatment System Performance
24
Two-Year Effectiveness Study
  • Ongoing.
  • Performance testing results verified.
  • Continuing optimization.
  • Have met final effluent limitations at flows up
    to 390 MGD. Including the big rain events of
    late August 2007.

25
Facility Optimization
  • Pilot study and performance testing used 40 mg/L
    or more FeCl3 and up to 3 mg/L of polymer
  • while City now generally doses 10-30 mg/L
    FeCl3and 0.5-2 mg/L of polymer.
  • A lot of DensaDeg effluent sent to activated
    sludge system.
  • Jar testing of recent events to further optimize
    FeCl3 to polymer ratios.
  • Generally constant ratio whether dosing 45 and
    1.5 mg/L or 15 and 0.5 mg/L (FeCl3 and polymer,
    respectively).

26
Some Lessons Learned
  • Density meters and blanket sludge depth detectors
    not necessary for intermittent operation
  • Startup for intermittently operating facility
    takes longer to work out glitches longer
    warranty period is helpful
  • Returning HRT effluent to secondary can inhibit
    nitrification
  • Alkalinity consumption (HRT nitrification) ?
    loss of effluent buffering capacity (pH concerns)

27
HRT Construction Costs
232 MGD Capacity
0.29/gpd
28
HRT Annual OM Costs
Treating 1000 MG/yr
89/MG
29
  • Questions ???
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