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Draft 11
DISTRICT OF COLUMBIAWATER AND SEWER AUTHORITY
Biosolids Management Program Update
May 22, 2008
Draft 22
Agenda
BMP Status Update
Process Alternatives
Comparison of Alternatives
Risk Management Strategy
Energy and GHG Emission Considerations
Implementation Schedule
Draft 44
Introduction
WASA has been updating the BMP to:
• Determine available technologies for Blue Plains
• Define projects that can be implemented within the budget, but also identify projects that provide significant O&M cost advantages
• Define projects that significantly reduce continued use of lime stabilization and provide for beneficial use of final product (i.e., digester gas and biosolids)
Draft 55
Introduction WASA has determined that:
• Digestion remains the cornerstone of the BMP
• WASA should continue moving toward processes that result in Class A biosolids for program sustainability
• Thermal Hydrolysis by Cambi is proven to be an effective biosolids treatment technology
• Use of Cambi process can reduce needed digester volume by 50%
• Diversity of final product is an important risk management strategy
Draft 66
BMP Status WASA conducted three expert panel
workshops resulting in a recommended combined option including TH, digestion, and drying
• Waste activated (hard to digest sludge) to Cambi, and Primary (easy to digest sludge) to digestion/drying
• Reduces risk from processing all sludge using only one technology
• Generates diverse final biosolids products
• Allows WASA to gain experience with both technologies and decide which technology to proceed with in the future
Draft 77
BMP Status (Cont’d)
Identified process alternatives that would maximize use of existing facilities
Identified scaled-back facilities that fit within available budget
Performed value engineering with independent team on alternatives to identify construction cost savings
Performed independent cost analyses to validate cost assumptions and factors used to prepare construction and O&M cost estimates
Draft 88
BMP Status (Cont’d)
Validated feasibility and constructability concepts using independent construction and geotechnical experts
Identified risks related to construction and means to mitigate them (construction cost market continues to escalate at a rapid rate)
Estimated energy production and carbon offsets for each alternative
Draft 99
BMP Status (Cont’d)
Reviewed latest population projection for Blue Plains service area and impact on solids loading and biosolids management costs
DCWASA personnel visited TH (Cambi) installations in Ireland and the United Kingdom April 29 – May 2, 2008 to: • Inspect operating and partially constructed TH
plants• Discuss procurement, construction and operating
issues with owners• Familiarize WASA staff with process operability
and maintainability requirements• Found Cambi to be an acceptable technology for
Blue Plains
Draft 1010
Process TechnologiesCambi Thermal Hydrolysis (TH)
TH precedes anaerobic digestion TH uses high temp and pressure to break down
sludge for faster digestion and destroys all pathogens
TH produces Class A biosolids product TH reduces the required digester volume by half TH can provide diversity of biosolids product with
the addition of drying
Thickening Dewatering Cambi Meso DigestionDewatering Beneficial Use (Class A)
Draft 1111
Digestion/Drying
• Provides heat dryers for digested sludge to yield Class A pellets
• Reduces biosolids volume by 90%
• Class A pellets can be land applied or used for fertilizer or fuel
Process Technologies
Thickening Meso Digestion Dewatering DryingBeneficial Use (Class A)
Draft 1212
Thickening Dewatering Cambi Meso DigestionDewatering Beneficial Use (Class A)
Thickening Meso Digestion Dewatering DryingBeneficial Use (Class A)
Primary Solidsand WAS
Combined (Cambi/digestion/drying)
• Provides heat dryers for non-Cambi digested sludge to yield Class A pellets
• Provides two different types of Class A products
Process Technologies
Draft 1313
Available ProjectConstruction Budget
Current Available CIP Funds = $ 308 MM
Pre-construction Cost Allowances
at 26% of Construction Cost = $ 64
MM
Available Construction Budget = $ 244 MM
Draft 1414
Process Alternatives – Major Equipment
Alt.CambiTrains
Digesters DryersAdditional
CentrifugesLocation
1 6 5 0 5 Digester site
2 4 4 0 3 Digester site
3 2 2 0 5 SPB
4 2 2 0 2 Digester site
5 2 7 3 3 Digester site
6 2 3 1 7 SPB
7 1 5 2 3 Digester site
8 1 3 1 3 Digester site
9 1 3 1 3 SPB
10 0 8 5 6 Digester site
11 0 4 3 1 SPB
12 0 0 0 6 SPB
SPB = Sludge Processing Building
Draft 1515
Biosolids Loadings and Construction Cost for Alternatives
Alt. No.
Loading (dtpd)
Construction Cost
($ Million)
To Treatment To Lime Stabilization
Annual Average Max 3-D/ Annual Average
1 370 0 / 0 375
2 370 162 / 0 311
3 220 409 / 150 214
4 220 409 / 150 220
5 370 80 / 0 370
6 261 352 / 109 300
Draft 1616
Biosolids Loadings and Construction Cost for Alternatives
Alt. No.
Loading (dtpd)
Construction Cost
($ Million)
To Treatment To Lime Stabilization
Annual Average Max 3-D/ Annual Average
7 292 286 / 78 355
8 202 408 / 168 258
9 202 408 / 168 237
10 370 126 / 0 413
11 200 392 / 170 232
12 0 657 / 370 137
Draft 1717
Construction and O&M Costs of Alternatives
Alt.No.
Description Construction ($M)
1st Yr. O&M($M)
1 6 Cambi (Digester site) + 5 MAD (Full) 375 34.4
2 4 Cambi (Digester Site) + 4 MAD + LS 311 24.6
3 2 Cambi (SPB) + 2 MAD + LS 214 * 34.3
4 2 Cambi (Digester Site) + 2 MAD + LS 220 34.3
5 2 Cambi (Digester Site) + 7 MAD +3 Dryers (Full) 370 24.9
6 2 Cambi (SPB) +3 MAD + 1 Dryer + LS 300 * 34.3
7 1 Cambi (Digester Site) + 5 MAD + 2 Dryers + LS 355 28.8
8 1 Cambi (Digester Site) + 3 MAD + 1 Dryer + LS 258 39.8
MAD = Mesophylic Anaerobic Digesters
LS = Lime Stabilization
Draft 1818
Construction and O&M Costs of Alternatives
Alt.No.
Description Construction ($M)
1st Yr. O&M($M)
9 1 Cambi (SPB) + 3 MAD + 1 Dryers + LS 237 * 39.8
10 Acid Hydrolysis + 8 MAD + 5 Dryers (Full) 413 15.0
11 4 MAD + 3 Dryers (SPB) + LS 232 * 28.2
12 Lime Stabilization (LS) (Full) 137 42.2
* The estimated cost does not account for additional costs that may be incurred when major equipment is installed in an existing building designed for other uses.
Draft 1919
Preliminary Comparison of Alternatives
Alternatives sized to handle all peaks and eliminate lime stabilization and cost >$370 Million (construction cost)
Cambi requests outdoor location for their process. Fitting Cambi into existing building could require modifications to their standard design which increases risk
Four digestion alternatives are within capital budget
Draft 2020
Preliminary Comparison of Alternatives (Cont’d)
Four digestion alternatives are above capital budget, but reduced O&M cost warrants further consideration
For each of the above, the best Cambi and combined alternatives were selected resulting in four alternatives to be compared with the base case full lime stabilization alternative
Draft 2121
Recommended Alternatives for Consideration
Alt. 2: Cambi – 4 trains/4 digesters (w/LS for peaks and Cambi down time)
Alt. 4: Cambi – 2 trains/2 digesters (w/LS)
Alt. 7: Combined – 1 Cambi /5 digesters/ 2 dryers (w/LS for peaks and Cambi
down time)
Alt. 9: Combined – 1 Cambi/3 digesters/1 dryer (w/LS)
Alt 12: Lime stabilization only (base case)
Draft 2222
Risk Management Strategy
Cambi Alternatives with Lime Stabilization (Alt. 2 & 4)
• Phased implementation allows confirmation of technology and later expansion based on plant operating data and a better definition of peak loads
• Use of conventional digester construction increases contractor competition
• Lime stabilization manages peak solids loadings and provides backup to mitigate potential risks
• Modular Cambi construction reduces initial installation costs
Draft 2323
Risk Management Strategy
Combined Alternatives with Lime Stabilization (Alt. 7 & 9)
• Phased implementation allows confirmation of technology and later expansion of either Cambi or drying
• Diversity of Class A biosolids products (Cambi cake and heat-dried biosolids) increases marketability
• Use of conventional digester construction increases contractor competition
Draft 2424
Risk Management Strategy (Cont’d)
• Lime stabilization manages peak solids loadings and provides backup to mitigate potential risks
• Combined alternatives mitigate commercial risks and allow leveraging competition
Draft 2525
Digester gas is used to generate electricity from a co-gen facility
Waste heat from power generation is used to provide energy for Cambi, drying and to heat digesters
CO2 emissions were generated from:
• Net heat consumed by the process
• Net electricity consumed by the process
• Transportation fuel for land application of cake solids
• Lime usage
Reduction of CO2 emissions are a result of:
• Electricity and heat generated from the biogas
• Land application of cake
• Combustion of pellets in a cement kiln plant
CO2 benefits related to land application of stabilized biosolids are based on carbon sequestration and offsetting the use of chemical fertilizer
Comparative Green House Gas (GHG) Emissions Based on CO2
Draft 2626
(60.0)
(40.0)
(20.0)
0.0
20.0
40.0
60.0
Alt 2 Alt 4 Alt 7 Alt 9 Alt 12
(100)
(90)
(80)
(70)
(60)
(50)
(40)
(30)
(20)
(10)
0
Alt 2 Alt 4 Alt 7 Alt 9 Alt 12
CO2 Emission in thousand tons/yr for the selected alternatives
Red numbers in parenthesis represent negative CO2 emission or CO2 credit
The higher the numbers in ( ) the better the process in terms of GHG emission, considered as CO2 benefit.
Processes only
Processes and Product Use
Draft 2727
Electricity Productionfor Selected Alternatives
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Alt 2 Alt 4 Alt 7 Alt 9 Alt 12
Electricity, MW
Draft 2828
Basis for Selection of Recommended Alternative
Costs / Available budget
Diversity of Product
Complexity of Construction
Complexity of O&M
Carbon Offsets
Energy Production
Risks
Draft 2929
Project Implementation Schedule
Activity Duration Completion
Concept Development Report 4 months Sep 30, 2008
Design procurement 6 months Jan 2, 2009
Design 12 months Jan 8, 2010
Bidding 6 months Jul 9, 2010
Construction 29 months Dec 31, 2012
Startup 6 months Mar 29, 2013
Note: Some activities run concurrentlyNote: Some activities run concurrently
Draft 3030
Population Projection and Impacts
• Current budget based on 2000 population projections and 330 dt/d solids production
• New projections based on 2008 projections and 370 dt/d solids production
Draft 3131
Next Steps
Provide construction cost, schedule, May 27, 2008
and annual O&M costs to CFO
Technical Workshop June 4, 2008
Len Benson meeting with CFO and GM ~ June 9, 2008
EQ & Operations Committee meeting June 19, 2008
Full Board meeting (assumed) July 3, 2008
Draft and Final Report(Conceptual Development level) September 2008
Draft 3434
Cambi and Digestion Alternatives
Digester Gas
To Land Application
TPrimary To Land Application
5% TS
TWAS
Digester Gas
To Land Application
Post-CAMBI Centrifuges(Existing)
Dryers (New)
3.5 MG Digesters
(New)
DewateringCentrifuges(Existing)
3.5 MG Digesters
(New)
CAMBIProcess(New)
BlendingTank
(Existing)
Pre-CAMBICentrifuges(Existing)
DewateringCentrifuges (Existing)
Lime Stabilization(Existing)
Draft 3535
Cambi and Digestion Alternatives
Digester Gas
To Land Application
TPrimary 5% TS
TWAS
To Land Application
Post CAMBICentrifuges (Existing)
3.5 MG Digesters
(New)
CAMBIProcess(New)
BlendingTanks
(Existing)
Pre-CAMBI Centrifuges
(New)
Centrifuges (Existing)
Lime Stabilization(Existing)
Draft 3838
Cambi/ Digestion / Drying Digester Gas
To Land Application
TPrimary To Land Application
5% TS
TWAS
Digester Gas
To Land Application
Post-CAMBI Centrifuges
(New)
Dryers (New)
3.5 MG Digesters
(New)
DewateringCentrifuges (Existing)
3.5 MG Digesters
(New)
CAMBIProcess(New)
BlendingTank
(Existing)
Pre-CAMBICentrifuges(Existing)
DewateringCentrifuges (Existing)
Lime Stabilization
(Existing)
Draft 4141
Lime Stabilization
TPrimary
TWAS To Land ApplicationBlending
Tanks
DewateringCentrifuges(Existing)
Lime Stabilization(Existing)
DewateringCentrifuges
(New)