08. enery pickering

8/10/2019 08. Enery Pickering

1/15

S c i e n t i f i c a n d T e c h n i c a l C o n f e r e n c e

Extraction and Use of Renewable Thermal Energyfrom Small Wastewater Systems, Best Practices

Platinum Sponsor Silver Sponsor

W A T E R S E R V I C E S A N D T H E N E W E N E R G Y C H A L L E N G E S

P r e s e n t e d b y M i k e M e h a f f e y , P. E . , G a n n e t t F l e m i n g , I n c .

A u t h o r : M a r k P i c k e r i n g , G a n n e t t F l e m i n g , I n c ,


2/15

Thesis

New equipment designs now allow smaller (2,500m3/day30,000 m3/day) wastewater systems to achieve net positive

energy using anaerobic digestion


3/15

Discussion TopicsTypes and Uses of Wastewater Energy

Basic Types of Sludge Stabilization

Sludge Stabilization Energy Balance

Best Design and Operations Practices: Anaerobic Digestion

Case Study: Danville, Pennsylvania, USA


4/15

Wastewater is an Energy Resource

Chemical Energy inUntreated Wastewater

12-15 Mbtu/kg COD

Chemical Energy inPrimary Sludge, dry

15-15.9 Mbtu/kg TSS

Chemical Energy inSecondary Biosolids, dry

12.4 13.5 Mbtu/kg TSS

Thermal Energy @ 3,500m3/day, 15C

220 Mbtu

Thermal Energy @17,500 m3/day, 15C

1,099 Mbtu


5/15

Sludge Chemical Energy Anaerobic Digestion

Most Common:Mesophillic, 2-Stage

4.2 L biogas per kg VSS

converted Biogas = 640 ppm CH4

Gas Combustion inboiler or Combined

Heat and Power (CHP)Generator


6/15

Anaerobic Digestion is the Greatest Source of

WWTP Renewable Energy

Small WWTP Applications Common for Primary Treatment

WWTPs

Smaller systems need supplementalfuel for colder weather digestion

Can treat contract waste to increasegas formation

Limited CHP Potential but can bethermally self-sufficient

Large WWTP Applications Thermal self-sufficient

Excess gas for CHP Net Positive WWTP Energy Profile

0

10

20

30

40

50

60

70

80

19

60

70

76 77

Number with

Anaerobic

Digesters

Size Range, m3/day

Survey of Small WWTPs in U.S.


7/15

Anaerobic Digestion Has a Smaller NetEnergy than Aerobic Digestion

*Average Day, Summer

**Standard Practice for Mixing and Pumping Energy

Can anaerobic digestion be net energy positive?


8/15

Optimal Equipment Selection Can Achieve Net Energy Goal

Pump+Nozzle Mixing Efficient mix, Lower Operating

Times

Linear Motion Mixer

Up to 70% smaller motor High Efficiency Heat

Exchange

Biogas Storage

Membrane


9/15

Best Practice Chemically Enhanced PrimaryTreatment


10/15

Summary of Anaerobic Digestion Practices


11/15

Case Study: Danville, PA, U.S.A.

14,000 m3/day Design Flow 2-Stage, Mesophillic Anaerobic Digestion

Removal of Primary Sludge and WAS throughPrimary Clarifiers

Connected Loads and Physical Plant Used toModel Energy Balance

Average Monthly Temperatures Used to Model

Heat Input to Sludge Compared Standard and Best Practices


12/15

Temp Impact on Digester Net Energy


13/15

Best Practices Can Achieve Net

Positive Energy Balance

(10,000)

(8,000)

(6,000)

(4,000)

(2,000)

-

2,000

4,000

6,000

8,000

10,000

ProcessEnergy,MBtu

Standard

Best Practice

Model Data


14/15

Optimal Equipment at Small WWTPs

Yield Valuable Benefits Increases Renewable Energy Yield

Reduces Greenhouse Gas Emissions

Produces a more stable sludge

Reduces Operating Costs

A more sustainable solution


15/15

Questions?

Mike Mehaffey

[email protected]

08. enery pickering

Documents