Transcript An Introduction to Membrane Softening Options for Sioux Falls

Moving Bed Biofilm Reactor
Retrofit for Ammonia
and Nitrate Removal
B&V
Lela Parsons, P.E.
Mark Maxwell, P.E.
SACWSD
Greg Fabisiak
Joan Chavez
2002 RMSAWWA / RMWEA ANNUAL CONFERENCE
Phase 2 Project Components
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Wastewater Collection System Master Plan
Utility Plan
Preliminary Design Report
Detailed Plans & Specifications
Contract Administration
Utility Plan Goals
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Provide information required by DRCOG and for
SRF Funding
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Evaluation of existing facilities
Population & flow projections
Environmental assessment to support FNSI
Alternative analysis and recommendations
Implementation and financial plans
Public participation
Determine necessary wastewater facilities for
capacity and regulatory compliance through 2020
Site Layout
WM WWTP Existing Unit Processes
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East
Trickling
Filter
Final
Clarifiers
Chlorination
Flow Splitter
Raw
Wastewater Mechanical
Screenings
P
Rotating
Biological
Contactors
Primary
Clarifiers
P
Combined
Primary &
MBBR
Sludge
Degritting
Gravity
Thickener
Anaerobic
Digesters
West
Trickling
Filter
P
Dechlorination
Final
Clarifier
Deskins
“Quick-Dry”
Filtration SystemTM
Discharge
to South
Platte River
Chlorination
Accelerated Air Drying of Dewatered
Biosolids Prior to Ultimate Disposal
of Class A Product
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WM WWTP Existing Unit
Process Capacities
12.0
10.0
10.0
8.0
7.8
4.0
8.4
8.8
8.3
7.0
6.0
4.4
4.2
2.8
2.4
2.0
0.0
Treatment Issues
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Regulatory Compliance
– Reclassification of the South Platte River requires additional
disinfection
– Updated model of Segment 15 of the South Platte River
resulted in imposition of effluent ammonia limit
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Current and Future Water Quality Concerns
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Dissolved oxygen
Ammonia
Nitrates
Nutrients
Centennial
LittletonEnglewood
South
Segment 14
Clear Creek
MWRD
Central Plant
Cherry Creek
Chatfield
Reservoir
Bear Creek
South Platte Dischargers
SACWSD
River
Platte
Burlington
Ditch Diversion
Glendale
Brighton
Future Sand Creek
Satellite WWTP
Segment 15
Segments 14 & 15 of South Platte River
(Not shown are non-point sources, diversion dams, reaeration structures etc.)
Treatment Issues (con’t)
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WM WWTP Treatment Capacity
– Surge in residential and commercial activity in the service
area
– Current treatment capacity of 4.4 mgd forecasted to only
be sufficient through 2003
– Limited room for additional expansion at the existing site
SACWSD Future Plan
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Complete Phase 2 expansion at WM WWTP by
2004
Phase 2 will provide capacity until 2008
New WWTP will be needed by 2009- could be
regional WWTP or SACWSD WWTP
Upgrade WM WWTP when appropriate to meet
future water quality regulations
WM WWTP Expansion
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Increase treatment capacity from 4.4 to 7.0 mgd
Notice to proceed issued September 2002
Short-term - capacity expansion allows growth
while new WWTP is designed and constructed
Long-term -WM WWTP will continue to serve the
southern area
of the District
Phase 2 Improvements
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Major Expansions
– Secondary Treatment Process
– Solids Handling Process
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Additional Improvements
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Replace Manual Bar Screen
Demolish RBCs
Upgrade Disinfection Facilities
Add Stand-by Power Capacity
Expand Administration Building/Garage
Treatment Alternatives
Alternative A
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Activated Sludge
Alternative B
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– Anoxic/oxic basins
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WAS Pumping Station and
Blower Building
New Aerobic Sludge
Handling
– MBBR
– Anoxic/oxic basins
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– Centrifuge
– Aerated sludge holding
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Biological Nutrient
Removal (future)
Fixed Film
Blower Building
Additional Anaerobic Solids
Processing
– Convert secondary digester to
primary digester
– New secondary digester
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Chemical Phosphorous
Removal (future)
Post Denitrification (future)
Alternative Evaluation
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Alternative A slightly less expensive
Alternative A more operationally complexrequires separate solids handling process
Alternative B will require chemical addition for
future phosphorous removal
SACWSD has always utilized and prefers fixed film
processes
Selected Alternative:
Moving Bed Biofilm Reactors
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Fixed film process manufactured by Kaldnes
Employs high-density polyethylene plastic media,
coarse bubble aeration, and sieves
Biofilm grows on inside of the media
Specific gravity
of 0.96
150 ft2/ft3 media
surface area
0.93 %/ft clean
water oxygen
transfer rate
Design Conditions
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100 mg/L influent BOD
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2 anoxic and 2 oxic reactors in series
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60% fill in each reactor
Coarse bubble diffuser system in oxic reactors
Submersible propeller mixers in anoxic reactors
4 mg/L summer DO concentration
5 mg/L winter DO concentration
200% internal recycle for nitrate removal
Treatment Requirements
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East Plant Effluent
– BOD5 reduction <10 mg/L
– Total ammonia reduction <2 mg-N/L (complete
nitrification)
– Total nitrate reduction <10 mg-NO3/L (partial
denitrification)
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Blended Effluent (East and West Plant)
– CBOD reduction <25 mg/L
– Total ammonia reduction <10 mg-N/L
Selected Alternative Flow Schematic
East
Trickling
Filter
Anoxic
MBBR
Oxic
MBBR
Final
Clarifiers
Chlorination
P
P
Raw
Wastewater Mechanical
Primary
P
Screenings
Clarifiers
Dechlorination
Discharge
to South
Platte River
Flow Splitter
P
Combined
Primary &
MBBR
Sludge
Degritting
Gravity
Thickener
West
Trickling
Filter
Anaerobic
Digesters
Final
Clarifier
P
Deskins
“Quick-Dry”
Filtration SystemTM
Chlorination
Accelerated Air Drying of Dewatered
Biosolids Prior to Ultimate Disposal
of Class A Product
Existing Facilities
Phase 2 New
Phase 2 Modified
Operational Issues
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Portion of primary effluent must be bypassed
around existing trickling filter
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Requires construction of a new flow splitter structure
Prevents hydraulic surcharging of underdrains
Assures sufficient soluble BOD for denitrification
Allows ETF pumping station to be taken out of service
Trickling filter snail accumulation
– Installed an automatic, self-cleaning strainer with 1/8- inch
openings at the ETF pumping station
Total Project Costs
Engineer’s Construction
Cost Opinion
$13,283,000
Low Bid Price
$12,774,000
Difference Between High
and Low Bids
$475,300