1 draft1 district of columbia water and sewer authority biosolids management program update may 22,...

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DISTRICT OF COLUMBIAWATER AND SEWER AUTHORITY

Biosolids Management Program Update

May 22, 2008

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Agenda

BMP Status Update

Process Alternatives

Comparison of Alternatives

Risk Management Strategy

Energy and GHG Emission Considerations

Implementation Schedule

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BMP Status Update

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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)

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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

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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

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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

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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

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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

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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)

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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)

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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

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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

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Process Alternatives – Major Equipment

Alt.CambiTrains

Digesters DryersAdditional

CentrifugesLocation

1 6 5 0 5 Digester site


3 2 2 0 5 SPB



6 2 3 1 7 SPB



9 1 3 1 3 SPB


11 0 4 3 1 SPB

12 0 0 0 6 SPB

SPB = Sludge Processing Building

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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

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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

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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

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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.

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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

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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

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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)

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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

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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

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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

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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

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(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


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

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Electricity Productionfor Selected Alternatives

0.0

1.0

2.0

3.0

4.0

5.0

6.0


Electricity, MW

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Basis for Selection of Recommended Alternative

Costs / Available budget

Diversity of Product

Complexity of Construction

Complexity of O&M

Carbon Offsets

Energy Production

Risks

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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

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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

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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

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THE END

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Schematics and Site Layouts of Alternatives

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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)

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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)


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Cambi/DigestionAlternative #2

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Cambi/DigestionAlternative #4

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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)


3.5 MG Digesters

(New)

CAMBIProcess(New)

BlendingTank

(Existing)

Pre-CAMBICentrifuges(Existing)


Lime Stabilization

(Existing)

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Insert Layout for Alternative 7

Cambi/Digestion/DryingAlternative #7

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Cambi/Digestion/DryingAlternative #9


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Lime Stabilization

TPrimary

TWAS To Land ApplicationBlending

Tanks

DewateringCentrifuges(Existing)


DewateringCentrifuges

(New)

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Lime StabilizationAlternative 12


1 draft1 district of columbia water and sewer authority biosolids management program update may 22,...

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