HERAKLION 2019 International Conference on Sustainable Solid Waste - - PowerPoint PPT Presentation

Performance comparison between mesophilic and thermophilic anaerobic digestion processes carried out on waste activated sludge

• A. Cerutti1, G. Campo1, M.C. Zanetti1, G. Scibilia2, E. Lorenzi2, B. Ruffjno1

1Department Environment, Land and Infrastructure Engineering, Politecnico di T

• rino, T
• rino, I-10129, Italy

2Research Center, Società Metropolitana Acque T

• rino S.p.A., Viale Maestri del Lavoro, 4 – 10127 T
• rino, Italy

HERAKLION 2019

International Conference on Sustainable Solid Waste Management 26 – 29 June 2019

Extracellular Polymeric Substance (EPS) Glowing color

from Shana et al., 2015

Bacteri a Dark- brown color http://www.cambi.com

Waste Activated Sludge MESOPHILIC AD

Low degradability ▼ Low effjciency of the AD process

• Low dewaterability

2 STRATEGIES

Pre / intermediate tretments

Extracellular Polymeric Substance (EPS) Glowing color

from Shana et al., 2015

Bacteri a Dark- brown color http://www.cambi.com

Waste Activated Sludge MESOPHILIC AD

Low degradability ▼ Low effjciency of the AD process

• Low dewaterability

2 STRATEGIES

Pre / intermediate tretments

THERMOPHILIC AD

?

Thermophilic AD of WAS in a 44L CSTR Thermophilic AD of WAS in a 300L CSTR

In this presentation:

EXPERIMENTAL PHASE MODELING PHASE

Simplifjed Anaerobic Digestion Model 1 (ADM1)

Calibratio n Validatio n Calibratio n Validatio n Mesophilic AD of WAS in a 300L CSTR

Thermophilic AD of WAS in a 44L CSTR Thermophilic AD of WAS in a 300L CSTR

In this presentation:

EXPERIMENTAL PHASE WA S k: fjrst order kinetics

costant [1/d]

B0: biomethane

potential [Nm3/kgVS]

MODELING PHASE

Simplifjed Anaerobic Digestion Model 1 (ADM1)

Calibratio n Validatio n Calibratio n Validatio n Mesophilic AD of WAS in a 300L CSTR Mesophilic cond. Thermophilic cond.

Experimental phase

300 L C.S.T.R. Digestate

(TS, VS, pH, FOS /

TAC) 5 days / week Biogas (CH4, CO2, O2, Bal.) 5 days / week

MESOPHILIC CONDITION 38°C, HRT 20 d THERMOPHILIC CONDITION 55°C, HRT 20 d

Pre-thickened WAS (TS, VS, pH, FOS / TAC) 5 days / week

Experimental phase

300 L C.S.T.R. Digestate

(TS, VS, pH, FOS /

TAC) 5 days / week Biogas (CH4, CO2, O2, Bal.) 5 days / week

MESOPHILIC CONDITION 38°C, HRT 20 d THERMOPHILIC CONDITION 55°C, HRT 20 d

Pre-thickened WAS (TS, VS, pH, FOS / TAC) 5 days / week 44 L C.S.T.R.

Experimental phase

300 L C.S.T.R. Digestate

(TS, VS, pH, FOS /

TAC) 5 days / week Biogas (CH4, CO2, O2, Bal.) 5 days / week

MESOPHILIC CONDITION 38°C, HRT 20 d THERMOPHILIC CONDITION 55°C, HRT 20 d

300 L C.S.T.R. Pre-thickened WAS (TS, VS, pH, FOS / TAC) 5 days / week 44 L C.S.T.R.

WAS sample

Thickened from 2,5 to 3% TS

Mesophilic inoculum

Castiglione T

• rinese SMAT WWTP

2,300,000 e.p.

Static pre-thickener Sludge line: from pre- thickeners to digesters

Thermophilic digesters

Thermophilic inoculum

naerobic Digestion Model 1 (ADM1) (Batstone DJ. et al., 2002) ying hypothesis:

• lysis is assumed to be the limiting step of AD  methane production can be modelled through a fjrst order k

Modeling phase

Experiment al phase

Industrial design

(optimal HRT)

k, B0 Bexp, VSexp removal

VSb

VSnb NVS VSb VSnb NVS

CSTR Digester

Biogas

VSTOT

VSb

VSnb NVS VSb VSnb NVS

CSTR Digester

Biogas

VSTOT

Y

THERMOPHILIC WAS AD 44 L CSTReactor 57 days AD 29 alimentations CALIBRATION

5 10 15 20 25 30 35 40 45 50 55 60 6 7 8 9 10 11 12 13 14

Daily VS concentration

Days kg VS / m3

THERMOPHILIC WAS AD K = 0,380 1/d Y = 42 % BO = 0,218 Nm3/kg VS

CALIBRATION

5 10 15 20 25 30 35 40 45 50 55 60 6 7 8 9 10 11 12 13 14

Daily VS concentration

Model Experimental

Days kg VS / m3

12 24 36 48 60 0,00 2,00 4,00 6,00 8,00 10,00 12,00

WAS Cumulative methane production

Model

Days Nm3

VALIDATION

THERMOPHILIC WAS AD K = 0,380 1/d Y = 42 % BO = 0,218 Nm3/kg VS

THERMOPHILIC WAS AD 300 L CSTReactor 58 days AD 35 alimentations

12 24 36 48 60 0,00 0,20 0,40 0,60 0,80 1,00 1,20 1,40

WAS Cumulative methane production

Model Experimental

Days Nm3

VALIDATION

THERMOPHILIC WAS AD K = 0,380 1/d Y = 42 % BO = 0,218 Nm3/kg VS

THERMOPHILIC WAS AD 300 L CSTReactor 58 days AD 35 alimentations Error < 1%

HRT =10 d HRT =10 d

CST Reactor Steady state condition

1 stage A.D. 2 stage A.D.

HRT =20 d

B20d = 0,193

Nm3/kg VS

B10+10d = 0,209

Nm3/kg VS

WAS A.D. in WWTP Castiglione Torinese Present conditions B20d = 0,090

Nm3/kg VS

WAS Mesophilic AD 38 °C

K = 0,085 1/d BO = 0,147 Nm3/kg

VS

WAS A.D. in WWTP Castiglione Torinese Present conditions B20d = 0,090

Nm3/kg VS

+ 108 %

Scenario 1 B20d = 0,193

Nm3/kg VS

WAS Mesophilic AD 38 °C WAS Thermophilic AD 55 °C

K = 0,085 1/d BO = 0,147 Nm3/kg

VS

K = 0,380 1/d BO = 0,218 Nm3/kg

VS

+ 347 %

WAS A.D. in WWTP Castiglione Torinese Present conditions B20d = 0,090

Nm3/kg VS

+ 108 % + 144 %

Scenario 1 Scenario 2 B20d = 0,193

Nm3/kg VS

B20d = 0,226

Nm3/kg VS

WAS Mesophilic AD 38 °C WAS Thermophilic AD 55 °C WAS Pretreatment + AD 38°C

NaOH 4g/100g TS + 90 °C, 1,5h

T O M O R R O W

K = 0,085 1/d BO = 0,147 Nm3/kg

VS

K = 0,380 1/d BO = 0,218 Nm3/kg

VS

+ 347 %

Conclusio ns

• The WAS AD in thermophilic condition improved the biochemical

methane potential by 50 % related to the mesophilic condition;

• The raw WAS was only slowly biodegradable (k =0.085 d-1) but the

thermophilic condition increased the hydrolysis constant by 347 %;

• Due to the thermophilic condition; the WAS biodegradability rose

from 28 to 42 %, with an increase of 50 %;

• In steady state condition with HRT equal to 20 days, the specifjc

methane production increase in the order of 108 % related to the mesophilic condition.

Performance comparison between mesophilic and thermophilic anaerobic digestion processes carried out on waste activated sludge

Thank you for your attention!

• A. Cerutti1, G. Campo1, M.C. Zanetti1, G. Scibilia2, E. Lorenzi2, B. Ruffjno1

alberto.cerutti@polito.it http://www.wearwe.polito.it

1Department Environment, Land and Infrastructure Engineering,

Politecnico di T

• rino, T
• rino, I-10129, Italy

2Research Center, Società Metropolitana Acque T

• rino S.p.A., Viale Maestri

del Lavoro, 4 – 10127 T

• rino, Italy

HERAKLION 2019

International Conference on Sustainable Solid Waste Management 26 – 29 June 2019