Energy RecoveryAlex Juan, Kenneth Gray, Jack Li, Stephany Wei

Project Background

South Kitsap Water Reclamation Facility • Completed in 1985.• Membrane bioreactor was included in 2006.• Produces Class A effluent.

Current SKWRF Schematic

WAS

Anaerobic Digester

Primary

Clarification

Activated Sludge

Aeration

Screening

Centrifuge Thickening

CAHTS

Anaerobic Digester

Secondary

Clarification

Influent

Effluent

Class A Biosolid

Primary Sludge

Anoxic Tank

MBR

Project Goal

Independent of the electricity and heat grid!

Consumption

Consumption

Electricity Consumption

Heat Consumption

What can we do to recover these consumptions?

?

Solar

Water Furnace

??

Key Solution: Methane• Methane produced from the anaerobic digesters can:

• Produce electricity• Produce heat

• Current methane production: 13,000 ft3/day

Hangzhou Energy & Environment Co. https://engineering.purdue.edu/~jiqin/PhotoDigester/PhotosDigesters.html

How do we increase the methane production from the anaerobic digester?

Current Operations

Sludge fromClarifiers

Primary Thickener

Primary Digestion

Secondary DigestionCAHTS

Class A Biosolids

Scenario1. Primary Thickening

Codigestion

Scenario 2. Codigestion

Sludge fromClarifiers Primary

Digestion

Secondary Digestion

Food Waste + FOG Tank 1

Tank 2

CAHTSClass A Biosolids

Class B Biosolids

CAHTS

Class A Biosolids

Current Operations

Methane Production

Cogeneration• Generation of electricity and useful heat simultaneously• Alternatives Selection

• Stirling Engine• Microturbines• Fuel Cells

Micropower Europe http://www.micropowereurope.com/tecnology.html ACEEE http://www.aceee.org/sector/local-policy/case-studies/sheboygan-wastewater-treatment-plant-

Microturbines• Scenario 1

Sludge fromClarifiers

Primary Thickener

Primary Digestion

Secondary Digestion

Summer WinterQuantities 4 4

Electricity Output (kWh/day) 4900 5100 Heat Output (kWh/day) 8800 8500

Microturbines• Scenario 2

Summer WinterQuantities 8 8

Electricity Output (kWh/day) 11500 12400 Heat Output (kWh/day) 20600 20650

Sludge fromClarifiers Primary

Digestion

Secondary Digestion

Food Waste + FOG Tank 1

Tank 2

CAHTSClass A Biosolids

Class B Biosolids

Renewable Energy• Solar Energy

• Number of (16.15 sqft Panels): • Roof 1 = 323• Roof 2 = 414 • Roof 3 = 455 • Roof 4 = 138

Total = 1330 Panels Total Energy Production = 1537.8 kWh/day

• Hydro-Electric Energy • Head = 7.5 ft, efficiency = 25%, inflow = 1.87MGD• Total power generated = 10.51 kWh/day ~ 0.587 hp

Roof 2

Roof 1

Roof 3

Roof 4

1.5 sq-meter PV panelhttp://www.bdbatteries.com/solarpanels.php?id=13

Low-head Hydro using outfall

Summary• Scenario 1

• Scenario 2

  Summer WinterHeat (kWh/day)

Consumption 1254 4226Recovery 8882 8603Difference 7629 4377

Electricity (kWh/day)Consumption 7130 7130

Recovery 6533 6730Difference -597 -400

  Summer WinterHeat (kWh/day)

Consumption 1555 4975Recovery 20702 20742Difference 19146 15767

Electricity (kWh/day)Consumption 7130 7130

Recovery 11552 12437Difference 4422 5307

Example Energy Balance:

20600

4850

58

7130

Methane: 156000 ft3/day

49

12400

10.52

1611.5

Electricity Consumption

Electricity Consumption

MicroturbinesMicroturbines

Anaerobic Digesters

Anaerobic Digesters

Heat Consumption

Heat Consumption

Hydro PowerHydro Power

Water FurnaceWater

Furnace

Solar PowerSolar

Power

Solar PowerSolar

Power

Scenario 2 for Winter: (units in kWh/day)

Recommendations• Implement Scenario 2.

• Future Consideration: Replace tanks with a third anaerobic digester.

Sludge fromClarifiers Primary

Digestion

Secondary Digestion

Food Waste + FOG Tank 1

Tank 2

CAHTSClass A Biosolids

Class B Biosolids

Thank you!