Sustainable Energy Management Approaches in Wastewater Treatment

Facilities

Preconference Workshop

Saturday, October 13, 2007

Color Slides

Energy and Water are … Interdependent

Water for Energy and Energy for Water

Energy and power production require water:• Thermoelectric cooling• Hydropower• Energy minerals extraction/mining• Fuel Production (fossil fuels, H2, biofuels)• Emission control

Water production, processing, distribution, and end-use require energy:• Pumping• Conveyance and Transport• Treatment• Use conditioning• Surface and Ground water

Ray Ehrhard, 8:30 AMWater and Energy Interdependence - What are we in for… Where are we going?

Why Do We Care?

• For wastewater - energy represents

25-30% of the total plant O&M– Raw sewage pumping = 12%– Aeration = 52%– Solid handling = 30%– Lighting, heating, AC, and masc. = 6%

Jim Wheeler, 9:25 AMRenewable Energy for the Wastewater Industry: the Office of Water Perspective

Modeling Water Systems

• Detailed fresh and waste water flows and technologies

William Horak, et al 8:50 AMThe Energy-Water Nexus (EWN): a New York City Pilot Study

Single Parameter ComparisonsWastewater Treatment Plants

AwwaRF Survey, 2004 Data, 300 observations

0

10

20

30

40

50

60

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450

Annual Energy Cost ($/MG)

Nu

mb

er

of

Pla

nts

Wastewater Treatment PlantsAwwaRF Survey, 2004 Data, 279 observations

0

5

10

15

20

25

30

Annual Electricity Use (kWh/MG)

Nu

mb

er

of

Pla

nts

Steven Carlson, P.E., 10:30 AMDevelopment of a Utility Energy Index

Katy Hatcher, USEPA Energy StarFocusing on Energy Efficiency for theDrinking Water and Wastewater Industries Portfolio Manager:

Facility Summary View

One of NY’s Energy Champions: Albany North WWTP

0

5000

10000

15000

20000

25000

30000

35000

40000

1

Average KWH's/Day North Plant 1990-2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Fine bubble aeration

2006 2007-2011

VFDs; SCADA system

Enhancement to furnace control; add’l VFDs; add’l premium efficiency motors; building improvements

Premium efficiency motors; add’l VFDs

Waste heat recovery

Kathleen O’Connor, 11:00 AMWe’re Here to Serve: How Your State Energy Agency Can Improve Your Bottom Line

Daily DemandAugust 15, 2001

1600

1620

1640

1660

1680

1700

1720

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00

Time of Day

kW

Understand Electric DemandUnderstand Electric Demand

Joe Cantwell, 11:00 AMWe’re Here to Serve: How Your State Energy Agency Can Improve Your Bottom Line

Energy Efficiency Projects Generally Four Categories

Conservation Less Consumption

Efficiency -- Focus on Increasing Equipment & Process Efficiency

DO Probes in the ASPEfficient Pumps, Blowers, MotorsReplacement of Existing Diffusers with Energy

Efficient Membrane Diffusion SystemMotors with High Efficiency Motors and VFDSCoarse Bubble Diffusers with Fine Bubble DiffusersHigh Efficiency Motors, Microturbines, and Energy

Recovery SystemsPrimary Treatment Modifications

Generation -- Using Waste FuelsDG, Use of Digester Gas for CHP

Load Shifting -- Shifting Pumping Load to Off-Peak Hours by Increasing Storage Volume, Pumping

Capacity, Installing better pumping controls systems

Shahid Chaudhry, 11:00 AMWe’re Here to Serve: How Your State Energy Agency Can Improve Your Bottom Line

50%

41%

Pumping

25%

25%

42%

17%

Aeration

Diffuse

Electrical energyBiogas energySludgedryer

Heatingboilers

Flare

Lars Gunnarsson, et al, 2:30 PM Cost effective energy usage at Himmerfjärdsverket sewage treatment plant in Sweden

Tom Jenkins, Vikram Pattarkine, Mike StenstromEnergy Conservation by Optimizing Aeration Systems

Terminology• Efficiency

– Standard oxygen transfer efficiency (SOTE) (percent oxygen transferred)– Standard oxygen transfer rate (SOTR) (mass transferred per unit time)– Standard aeration efficiency (SAE) (mass transferred per unit time per unit

power)

• All “standard” terminologies defined for clean water such as tap water (secondary process effluent is never suitable for clean water testing)

• Process Conditions (OTE, OTR, AE)– Adjustment formulas based upon driving force, temperature, barometric

pressure, water quality, saturation concentration, etc.– Driving force and water quality the most significant

– Driving force = (DOS – DO)/DOS

– Water quality – alpha factor, 0 to 1 !– Total correction can result in process water transfer of only 30 to 80% of clean

water transfer

Diffuser Summary• Fine pore systems generally, but not always

offer the best energy conservation• Fine pore systems require a dedication to

maintenance; otherwise, select different alternatives

• Reputable manufactures have valuable experience with piping and assembly – Listen to them!

• The consultant or process engineer must define the efficiency – Require this information from them!

Tom Jenkins, Vikram Pattarkine, Mike StenstromEnergy Conservation by Optimizing Aeration Systems

Tom Jenkins, Vikram Pattarkine, Mike StenstromEnergy Conservation by Optimizing Aeration Systems

Energy Conservation:Blower Upgrades / Revamps

All Blower TypesProvide proper maintenance – filters, seals, diffuser cleaning

Change to energy efficient motors

Add smaller blowers to achieve turndown

Combine air use for other functions (Post-Aeration, Channel Aeration, etc.)

Update Controls

Tom Jenkins, Vikram Pattarkine, Mike StenstromEnergy Conservation by Optimizing Aeration Systems

Energy Conservation:Control System Techniques

All Blower Types

Automatic DO Control to match air rates to process demand

Use MOV Control to minimize pressure

Automatic starting and stopping of blowers

Parallel control instead of cascade control

Design Control System for Reasonable Payback – 2 to 5 years

Include Process Improvement in Evaluation

Robert Ostapczuk, P.E., 3:30 PMGloversville-Johnstown Joint Wastewater Treatment Facility Energy Conservation Program Case Study

Priority 1Aeration System Improvements Cont’d

• Overall project cost $1,500,000

• Total cost for new blower, Dissolved Oxygen (DO) automatic control, and more efficient diffusers ~ $1,000,000

• Energy savings with new system: 30% electricity decline immediately

• 1.3 M kwh saved annually

Robert Ostapczuk, P.E., 3:30 PMGloversville-Johnstown Joint Wastewater Treatment Facility Energy Conservation Program Case Study

Priority 2Anaerobic Digester Improvements

• Biogas Handling Piping– Plugged– Corroded

• Gas Mixing System– No mixing in Secondary

Digester– Poor mixing in Primary

Digester• Plugged lances• Inoperable valves

• Safety Handling Equipment– Inoperable Flare– Inoperable PRVs

Robert Ostapczuk, P.E., 3:30 PMGloversville-Johnstown Joint Wastewater Treatment Facility Energy Conservation Program Case Study

Priority 2Anaerobic Digester Improvements Cont’d

• Secondary Digester Floating Gas Holder Cover– Inoperable– Surface Corrosion

• Digester Tanks– Never Cleaned

• Internal Combustion Engine (ICE) Generators– Low electrical output

• 70% of rated capacity of one unit

– High maintenance requirements

Robert Ostapczuk, P.E., 3:30 PMGloversville-Johnstown Joint Wastewater Treatment Facility Energy Conservation Program Case Study

Priority 2Anaerobic Digester Improvements Cont’d

• Phase I (2002)– Flushed sediment and scale

from biogas piping and existing mixing system

– Overhauled ICE generators• Phase II (2005)

– Converted the existing floating gas holder to a fixed cover with a dual membrane gas holder

– Replaced biogas safety equipment

• Flare• Pressure relief valves

Priority 2Anaerobic Digester Improvements Cont’d

• Phase II (con’t)– Replaced sediment traps– Replaced DIP biogas piping

with SS• Replaced gas mixing system with

a confined gas mixer in both the primary and secondary digesters

• Phase III (2006)– 90,000 gallon acid whey

equalization tank– Acid whey feed system– 2-inch Ø HDPE acid whey

forcemain

Robert Ostapczuk, P.E., 3:30 PMGloversville-Johnstown Joint Wastewater Treatment Facility Energy Conservation Program Case Study

Engine or Turbine-based CHP

Tom Frankiewicz, 9:25 AMCHP for Wastewater Treatment Facilities – where efficiency and renewables meet

Biogas Use: Part of an Integrated Energy System

Electricity

HeatGasFuelFuelFuelFuel

Recovered Recovered HeatHeat

Recovered Recovered HeatHeat

Generated ElectricityGenerated ElectricityGenerated ElectricityGenerated Electricity

ImportImportImportImport

ExportExportExportExportPlant DemandPlant DemandPlant DemandPlant Demand

DigestersDigestersDigestersDigestersWaste GasWaste Gas

FlaresFlaresWaste GasWaste Gas

FlaresFlares BoilersBoilersBoilersBoilers

Digester Digester GasGas

Digester Digester GasGas

SupplementalSupplementalHeatHeat

SupplementalSupplementalHeatHeat

Natural Natural GasGas

Natural Natural GasGas

EffluentEffluentHeatHeat

RejectionRejection

EffluentEffluentHeatHeat

RejectionRejection

PlantPlantHeatHeat

DemandDemand

PlantPlantHeatHeat

DemandDemandOrganicOrganicWasteWasteOrganicOrganicWasteWaste

UtilityUtility

Vehicle FuelVehicle FuelVehicle FuelVehicle Fuel

Dave Parry, 2:00 PMRenewable Biogas Options

Dave Parry, 2:00 PMRenewable Biogas Options

Biogas Treatment Needed for Various Options

IronSponge

Heat Exchangeand Separator

Blower

ActivatedCarbon

ParticulateFilter

H2SReduction

Moisture Reduction PressureBoosting

SiloxaneReduction

ParticulateReduction

From

Digester

To

Beneficial Use

Point Loma BUDG Schematic

CompressedCompressedDigester GasDigester Gas

to Truckto Truck 3-Stage HP3-Stage HPCompressorCompressor

Feed fromFeed fromPLWTP GasPLWTP Gas

SystemSystem

FlareFlare

0 psig0 psig5 psig5 psig 0 psig0 psig

165 psig165 psig

BlowerBlower

Pre-PSADryer

Refrigeration

Pressure SwingAbsorption(PSA) Dryer

2-Stage2-StageCompressorCompressor

Pre-GranularActivatedCarbon

Refrigeration

GranularActivated

Carbon Filter

Pre-Membrane

Heater

150 psig150 psig

140 psig140 psig2600 psig2600 psig

C02 RemovalMembrane

Unit

Condensate Return to Wastewater Plant

C0C022

C0C022

SulfurRemoval

Fuel CellFuel Cell

Tom Alspaugh, P.E., 3:50 PMSustainable Energy Management Using In-House Resources

MWWD 30kW Photovoltaic System at MOC III

• 30 kW rooftop system at MOC III

• Under directive from Metro Commission, innovative rooftop mounting system and semiconductor technology were chosen

Tom Alspaugh, P.E., 3:50 PMSustainable Energy Management Using In-House Resources