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Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 ·...

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Maximizing Digester Gas Production to Create More Sustainable Maximizing Digester Gas Production to Create More Sustainable to Create More Sustainable Wastewater Treatment Facilities to Create More Sustainable Wastewater Treatment Facilities Dave Reardon PE BCEE Dave Reardon PE BCEE Dave Reardon, PE, BCEE National Director Water Sustainability Dave Reardon, PE, BCEE National Director Water Sustainability
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Page 1: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Maximizing Digester Gas Production to Create More Sustainable

Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Wastewater Treatment Facilitiesto Create More Sustainable

Wastewater Treatment Facilities

Dave Reardon PE BCEEDave Reardon PE BCEEDave Reardon, PE, BCEENational Director

Water Sustainability

Dave Reardon, PE, BCEENational Director

Water Sustainability

Page 2: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

To Be Truly Sustainable, You Want to To Be Truly Sustainable, You Want to Optimize the Impacts of the PlantOptimize the Impacts of the PlantOptimize the Impacts of the Plant Optimize the Impacts of the Plant

Inputs/OutputsInputs/Outputs

Energy(Electricity, Gas, Fuels)

AirEmissions

Chemicals Biosolids

VariousSupplies

Solid Waste

TreatedS pp

Raw Sewage,FOG Septage

TreatedEffluent

RenewableFOG, Septage,Food Waste

Renewable Resources

Page 3: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Today, We Are Going to Look at Today, We Are Going to Look at One InputOne Input

Energy(Electricity, Gas, Fuels)

How do we get to zeroget to zero

energy?

Page 4: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Can Your Plant Be Energy Can Your Plant Be Energy llNeutral?Neutral?

Page 5: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Few Wastewater Treatment Plants in the Few Wastewater Treatment Plants in the World Claim to Be Energy Self SufficientWorld Claim to Be Energy Self SufficientWorld Claim to Be Energy Self SufficientWorld Claim to Be Energy Self Sufficient

Strass Wastewater Treatment Plant, Austria

Page 6: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Treatment Process Selection Has a Treatment Process Selection Has a P f d I t E /S t i bilitP f d I t E /S t i bilitProfound Impact on Energy/SustainabilityProfound Impact on Energy/Sustainability

Energy5,000

6,000

Energy Intensity (kWh/MG) 3,000

4,000

1,000

2,000

Conventional Activated

Conventional Activated Sludge

Membrane Bioreactor

0

Activated Sludge

Activated Sludge with Nitrification-

Denitrification

Bioreactor (MBR)

Page 7: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Here’s How We Get to ZeroHere’s How We Get to ZeroGap: 11% Solar, Wind, More FOG, or Food Waste Carbon Credits90

100

Resolve Overdesign5%

6%5%

Waste, Carbon Credits

70

80

90EMS (Energy Management System)

Optimize Primary ClarifierFOG (Fats, Oil, and Grease) and Food Waste Digestion

25%50

60

70Contribution

% of Plant Power

4%8%30

40

50Power

Fuel Cell Cogeneration

6% Precondition WASPrecondition WAS

Conventional Cogeneration (Engines)30%10

20

Energy Reduction or Energy Production Ideas

Page 8: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

First and Foremost, You Will Need First and Foremost, You Will Need A bi Di ti fA bi Di ti f Bi lidBi lidAnaerobic Digestion of Anaerobic Digestion of BiosolidsBiosolids

C ti l Di tConventional Digesters

Egg-Shaped Digesters

Cambi

Page 9: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

So… How Can You Produce More So… How Can You Produce More Biogas So That You Can AchieveBiogas So That You Can AchieveBiogas So That You Can Achieve Biogas So That You Can Achieve

Net Zero Energy?Net Zero Energy?1. Capture more biosolids in raw wastewater

and divert to digesters2. Don't burn up biosolids

in the aeration system3. Condition biosolids (WAS)

prior to digestion4. Anaerobic digestion optimization5. Digester detention time5. Digester detention time6. Co-Digestion (FOG and food waste)

Page 10: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

But First.. How Much Biogas Will But First.. How Much Biogas Will Di t P d ?Di t P d ?Digesters Produce?Digesters Produce?

About 10,000 to 12,000 cfd digester gas per mgd

f l t fl (d ti I use 10,000 cfdof plant flow (domestic strength)

I use 10,000 cfd

This will produce 20 to 25 kW in a cogeneration faciityg y

Page 11: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

1. Capturing More 1. Capturing More BiosolidsBiosolids -- Improving Improving Primary Clarifier Performance Can MakePrimary Clarifier Performance Can MakePrimary Clarifier Performance Can Make Primary Clarifier Performance Can Make

A DifferenceA Difference

I d h d li d b ffli• Improved hydraulics and baffling can increase suspended solids (SS) removal b 10%by 10%

• SS = BOD = Energy inSS = BOD = Energy in activated sludge processprocess

Wh t W ld H if W R d 95%What Would Happen if We Removed 95% of SS Prior to Aeration?

Page 12: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

2. Don't Burn Up 2. Don't Burn Up BiosolidsBiosolids in the in the A ti S tA ti S tAeration SystemAeration System

0 8

1.0

1.2

Sludge

0 4

0.6

0.8Sludge Produced

(lb WAS/lb BOD)

0 00.2

0.4

0 2 4 6 8 10SRT (days)

12 14 16 18 200.0

Typical sludge production of the suspended growth process (sludge production quantities at 20º C)

Page 13: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

3. Condition 3. Condition

BiosolidsBiosolids Prior toPrior toBiosolidsBiosolids Prior to Prior to

Digestion Digestion -- The The gg

Wastewater Wastewater

Treatment Holy Treatment Holy

Grail: DestructionGrail: DestructionGrail: Destruction Grail: Destruction

of WAS Cell Wallsof WAS Cell Walls

Page 14: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Oh, These Poor BugsOh, These Poor Bugs, g, g

Pressure

HeatFreezing

ElectricityVacuum

CellMechanical

UltrasonicMechanicalAbrasion

Just About Everything Has Been Tried, with Mixed Results

Page 15: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

One Interesting Approach/Concept: One Interesting Approach/Concept: C Di i t ti S tC Di i t ti S tCrown Disintegration SystemCrown Disintegration System

Page 16: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Flow Schematic Flow Schematic -- Crown Disintegration Crown Disintegration S t f thS t f th Bi tBi t AGAGSystem of the System of the BiogestBiogest AGAG

3% 8% S3% to 8% TWASThickener of the Sewage

Treatment Plant Digester

External Signal ~30%

Control

Recycle 3XPanel Relaxation

Tank

Return NozzlePC

Macerator

Return Pump

NozzlePC Pump 10 Bar

Page 17: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Benefits Claimed by Benefits Claimed by BiogestBiogestyy gg

• Digester foaming “eliminated”

• Biogas yield increased 16% to 40%

Hi h VS d i ll 20%• Higher VS destruction; usually >20%

• Reduced sludgeReduced sludge hauling; usually ~20%

D t i i d• Dewatering improved 3% to 6%

• Guarantees are offered

Page 18: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Claimed BenefitsAnother Another

Technology is Technology is Biosolids Reduction

I d Bi OpenCELOpenCEL: High : High Voltage Voltage

Increased Biogas

Carbon Source Denitrification ggMicropulsesMicropulses of of

ElectricityElectricityReduced Pathogens

Reduced Odor yyReduced Odor

Reduced Greenhouse Gas

Page 19: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

But Wait! There is No Free Lunch… But Wait! There is No Free Lunch… C idC idConsider:Consider:

All WASAll WAS pretreatment systems use electricity, and sometimes gobs of it

Some may use chemicals

Mechanical complexity (O&M)

Performance claims verification

Piloting is Needed for Feasibility Analysis

Page 20: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

4. Anaerobic Digestion Types Can 4. Anaerobic Digestion Types Can I Bi P d tiI Bi P d tiIncrease Biogas ProductionIncrease Biogas Production

Acid Phase Digestion1 Thermophilic2

Temperature

g

3

Temperature-Phased

Anaerobic Digestion

(TPAD) Cambi4

Page 21: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

5. Digester Detention Time 5. Digester Detention Time -- Detention Time Detention Time is Impacted by Feed Solids Concentrationis Impacted by Feed Solids Concentrationis Impacted by Feed Solids Concentrationis Impacted by Feed Solids Concentration

35 1 MG Digester

253035

Digester

1 MG Digester17,000 lbs/day Biosolids

101520

Digester SRT

(days)

05

10

2 3 4 5 6Feed Solids (%)

Higher SRT More Biogas

Page 22: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

6. Co6. Co--Digestion is the 900 lb Digestion is the 900 lb G ill i th RG ill i th RGorilla in the RoomGorilla in the Room

FOG and Food Waste

Page 23: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

FOG Digestion and Food Waste Can Increase FOG Digestion and Food Waste Can Increase Bi P d ti b 50 t 200%Bi P d ti b 50 t 200%Biogas Production by 50 to 200% Biogas Production by 50 to 200%

• Virtually 100% volatile• Virtually 100% volatile solids destruction

Hi hl d d bl• Highly degradable

• Relatively easy to accept, process, and find

• Very small increase inVery small increase in biosolids production

• May improve volatile• May improve volatile destruction of primary/WAS

Page 24: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Digester Gas Production Digester Gas Production vs Greasevs Grease FeedFeedvs. Grease vs. Grease Feed Feed

(City of Watsonville Wastewater Treatment Plant(City of Watsonville Wastewater Treatment Plant250 500

200

250

400450500

Digester Gas

Digester Gas

(1,000

Grease Feed (1,000 ll /

150250300350

( ,CFD) gallons/m

onth)

50

100

100150200250

0

50

050100

Grease Feed

2001 2005Nov May Dec Jun Jan Aug Feb Sep Mar Oct Apr

2002 2003 2004 2006 2007

Page 25: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

We've Learned a Few Things Along We've Learned a Few Things Along th Wth Wthe Waythe Way

Page 26: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

East Bay Municipal Utility District East Bay Municipal Utility District (EBMUD) Has Perfected Organics(EBMUD) Has Perfected Organics(EBMUD) Has Perfected Organics (EBMUD) Has Perfected Organics

Conversion to BiogasConversion to Biogas• 90% energy neutral now,90% energy neutral now,

soon to be 100%• Aggressive FOG and food gg

waste programs• Dedicated food waste

digestion and dewatering• Thermophyllic digestion

Probably will be the first WWTP in US to "Get to Zero"

• Energy master plan is underway (energy use optimization and energy production)

• Three IC engines (2 MW each) and gas turbine (4.5 MW)

Page 27: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Here’s How We Get to ZeroHere’s How We Get to ZeroGap: 11% Solar, Wind, More FOG, or Food Waste Carbon Credits90

100

Resolve Overdesign5%

6%5%

Waste, Carbon Credits

70

80

90EMS (Energy Management System)

Optimize Primary ClarifierFOG (Fats, Oil, and Grease) and Food Waste Digestion

25%50

60

70Contribution

% of Plant Power

4%8%30

40

50Power

Fuel Cell Cogeneration

6% Precondition WASPrecondition WAS

Conventional Cogeneration (Engines)30%10

20

Energy Reduction or Energy Production Ideas

Page 28: Maximizing Digester Gas Production to Create More Sustainable … Maximizing... · 2011-09-15 · Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Maximizing Digester Gas Production to Create More Sustainable

Maximizing Digester Gas Production to Create More Sustainableto Create More Sustainable

Wastewater Treatment Facilitiesto Create More Sustainable

Wastewater Treatment Facilities

Dave Reardon PE BCEEDave Reardon PE BCEEDave Reardon, PE, [email protected]

Dave Reardon, PE, [email protected]


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