comparison of wastewater sludge drying processes: solar...

TINOS 2015 TINOS 2015 1

Comparison of wastewater sludge drying processes:

solar, thermal and reed beds

Impact on organic matter characteristics

Marie Collard, Benoit Teychené, Laurent Lemée

University of Poi<ers, France

CNRS UMR 7285 (IC2MP), Water Geochemistry Health Team

TITRE DE LA PRÉSENTATION / DATE / 2

TINOS 2015

Waste Production

(per year / inhabitant)

354 kg

46 kg

25 kg 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6

2003 2007 2005 2006 2007 2012

Mt

Sludge production in France

2004


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9%

19%

72%

Land farming

Landfill

Incineration

Annual amount: 1.5 M tons / year in France

Sewage sludge disposal


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Changes in European law will induce :

1.  Increase in production of sludge

(13 M tons expected in Europe in 2020)

2.  End to unsustainable recovery methods

9%

19%

72%

Land farming

Landfill

Incineration

Annual amount: 1.5 M tons / year in France

Sewage sludge disposal


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Reduce the volume

If we don’t want to be submerged ….

Drying process


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Reduce the volume

If we don’t want to be submerged ….

-> Understand impact of drying processes on sludge organic matter (OM)

characteristics

-> Propose elements to optimise disposal and / or re-use of WWS

Aim of the study : Characterise the biomass

Drying process


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It’s here


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It’s here

Thermal drying

Reed beds drying

Solar drying


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Thermal drying

LF-‐85 LF-‐120

pellets

Fer@lizer

hours

LF-‐0

Large WWTP : > 100,000 PE


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Solar drying

Thermal drying

LF-‐85 LF-‐120

pellets

Fer@lizer

hours

month

Solar-‐0 Solar-‐2w Solar-‐4w

Amendment

LF-‐0


Medium WWTP : > 2,000 PE


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Reed beds drying

Solar drying

Thermal drying

LF-‐85 LF-‐120

pellets

Fer@lizer

hours

month

years

Solar-‐0 Solar-‐2w Solar-‐4w

Amendment

RB-‐0 RB-‐1 RB-‐2

Amendment

RB-‐3 RB-‐4

LF-‐0


Medium WWTP : > 2,000 PE

Small WWTP


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OM characterisation

Sampling

Centrifugation

Freeze drying

Analysis

Bulk scale

1.  Elemental analysis (C, H, N) 2. Infra-red spectroscopy (ATR-FTIR) 3.  Thermal differential analysis (TDA) OM fractionation Lipids, Fulvic acids, Humic acids, Humin Molecular scale 1.  Double shot pyrolysis (Py-GC/MS)


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ATR-FTIR

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

650 1150 1650 2150 2650 3150 3650

Absorbance

cm-‐1

ν O

-H ,

ν N

-H

ν C=

C

ν C=

O

ν C-

H

δ C-

O

Iden@fica@on of bands in OM as sample fingerprints

Monitoring of transforma@on of OM such as aroma@sa@on (C=C), oxida@on (C-‐O)


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ATR-FTIR

2,0

2,5

3,0

3,5

4,0

0,5 1,5 2,5 3,5 LF-‐0 LF-‐85 LF-‐120

Thermal Drying

Reduction process

C-O/C-H ratio

2,0

2,5

3,0

3,5

4,0

4,5

0,5 1,5 2,5 3,5

Solar Drying

Solar-‐0 Solar-‐2w Solar-‐4w 2,0

2,5

3,0

3,5

4,0

4,5

0 2 4 6

Biological oxidation ?

Reed beds Drying


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ATR-FTIR

2,0

2,5

3,0

3,5

4,0

0,5 1,5 2,5 3,5 LF-‐0 LF-‐85 LF-‐120

Thermal Drying

Reduction process

C-O/C-H ratio

2,0

2,5

3,0

3,5

4,0

4,5

0,5 1,5 2,5 3,5

Solar Drying


2,5

3,0

3,5

4,0

4,5

0 2 4 6


Reed beds Drying


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Organic matter fractionation

« Humin »

« Humic Acids »

« Fulvic acids »

Lipids

Sludge OM

Humic-like

Substances

CH2Cl2/MeOH

HCl

NaOH


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2w: OM complexification 4w: biodegradation

OM fractionation

0%

20%

40%

60%

80%

100%

LF-0 LF-85 LF-120

Thermal Drying

OM weakening

0%

20%

40%

60%

80%

100%

Solar-0 Solar-2w Solar-4w 0%

20%

40%

60%

80%

100%

RB-0 RB-1 RB-2 RB-3 RB-4

?

Reed beds Drying Solar Drying

Lipids Fulvic acids Humic acids Humin


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OM fractionation

0%

20%

40%

60%

80%

100%

LF-0 LF-85 LF-120

OM weakening

0%

20%

40%

60%

80%

100%


20%

40%

60%

80%

100%


?

Reed beds Drying Solar Drying Thermal Drying




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OM fractionation

0%

20%

40%

60%

80%

100%

LF-0 LF-85 LF-120

OM weakening

0%

20%

40%

60%

80%

100%


20%

40%

60%

80%

100%


Reed beds Drying

?

Solar Drying Thermal Drying



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Double Shot Thermochemolysis (Py-GC/MS)

Trapped compounds are desorbed Polymers degrade into volatile molecules

1st shot : Warm 2nd shot : Hot

GC-MS


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First Shot

Fatty acids

Stanols/sterols

-‐0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0 200 400 600 800 1000

Temperature Difference (°C/mg)

Temperature (°C)

TDA

Pyrogram at 350°C of sludge

Warm

350 °C


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Fatty acids

C16

C18 C15

Bacterial origin

*

*

2,1

2,2

2,3

2,4

2,5

0 1 2 3 4 LF-0 LF-85 LF-120

Plants


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Fatty acids

Bacterial origin

*

2,1

2,2

2,3

2,4

2,5

0 1 2 3 4 LF-0 LF-85 LF-120

Thermal drying : decrease

inhibi@on of bacterial ac@vity

C16

C18 C15

*


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Fatty acids

Bacterial origin

*

2,1

2,2

2,3

2,4

2,5

0 1 2 3 4 LF-0 LF-85 LF-120

Thermal drying : decrease


Solar drying : stable

Reed beds drying : stable

C16

C18 C15

*


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Steroids

Stanol

4,2 4,3 4,4 4,5 4,6 4,7 4,8 4,9 5,0

0 1 2 3 4 LF-0 LF-85 LF-120

Sterol Reduc@on


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Steroids

4,2 4,3 4,4 4,5 4,6 4,7 4,8 4,9 5,0

0 1 2 3 4 LF-0 LF-85 LF-120

Thermal drying: increase


Stanols/ Sterols


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Steroids

4,2 4,3 4,4 4,5 4,6 4,7 4,8 4,9 5,0

0 1 2 3 4 LF-0 LF-85 LF-120

Thermal drying: increase


Solar drying: stable

Reed beds drying: stable

Stanols/ Sterols


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Second Shot

Lignin

Monomers originating from biopolymers degradation

Protein-like

-‐0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0 200 400 600 800 1000


Temperature (°C)

TDA


Hot

600 °C


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Second Shot

Lignin

Monomers originating from biopolymers degradation

No change induced by drying processes

Protein-like

-‐0,1

0

0,1

0,2

0,3

0,4

0,5

0,6

0 200 400 600 800 1000


Temperature (°C)

TDA


Hot

600 °C


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Conclusion


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1.  Thermal drying : 4 hours heating process - weakening of organic matter

- inhibition of bacterial activity

- stable but biodegradable OM better as fertilizer

Conclusion


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1.  Thermal drying : 4 hours heating process

2.  Solar drying : 1 month in a greenhouse process

- weakening of organic matter



- 0-2w complexification of organic matter (Hu increased)

- 2-4w biodegradation (lipid decreased)

- humified OM suitable for amendment

Conclusion


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3.  Reed beds drying : years outdoor process




- 0-2w complexification of organic matter (Hu increased)

- 2-4w biodegradation (lipid decreased)


- surface sampling : characteristics close than of acrivated sludge

- perspectives : sample an older reed beds drying process

Conclusion


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July 2015


3.  Reed beds drying : years outdoor process




- 0-2w complexification of organic matter

- 2-4w biodegradation


- surface sampling : characteristics close than of activated sludge

- perspectives : sample an older reed beds drying process

Conclusion

Thank you for your attention

comparison of wastewater sludge drying processes: solar...

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