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gress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001

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Page 1: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 1

LANDFILL MODEL SPECIFICATIONS

Fifth Framework Program

Progress meetingRennes, November 27-29, 2001

Progress meetingRennes, November 27-29, 2001

Page 2: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 2

Landfill modelling

Aim of work

Methodology

What is a landfill ?

Models specifications

Conclusions

Aim of work

Methodology

What is a landfill ?

Models specifications

Conclusions

Page 3: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 3

Aim of work DELIVRABLE:

SPECIFICATIONS OF LANDFILL MODELS Numbers of outputs Parameters Mathematical equation used

AIM: To supply the necessary information according to AWAST objectives

Matter balance Energetic balance Economical balance Environmental aspects

To simulate all the system of waste treatment

Page 4: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 4

Landfill modelling

Aim of work

Methodology

What is a landfill ?

Models specifications

Conclusions

Page 5: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 5

MethodologySeveral steps

1. How it works ?

2. Level 0 = a black box inputs outputs performance according to AWAST objectives

3. To increase the level of prediction fundamental parameters (calibration / sizing) cost of used

Page 6: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 6

Landfill modelling

Aim of work

Methodology

What is a landfill ?

Models specifications

Conclusions

Page 7: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 7

What is a landfill ?

Leachate generation

Waste

o

Water inflow from rainfall

Deposited Waste

t

Deposited Waste

t+1

Biogas

generation

Page 8: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 8

Waste degradation phenomenon...

Water (rainfall or waste) waste component mobilisation

Controlled by:• chemical reactions (oxidation, …) • physical aspects (adsorption, …)• biological reactions = principal factor

Authors agree to say reactions of organic matter biodegradation are the most accurate for leachate composition.

Page 9: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 9

Waste degradation phenomenon...

Principal reactions:

hydrolyze, aerobic oxidation, anaerobic degradation, acidogenesis, acetogenesis and methanogenesis

Final products of biodegradation:• Sulphur which precipitate with metals,• Hydrogen (consumed), • Methane and carbon dioxygen.

Page 10: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 10

I - Aerobic oxidationII - TransitionIII - Anaerobic degradationIV - Stable phaseV - Stable leachate

10-20 years

Page 11: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 11

Consequences for modelling tasks:

G° = f(waste composition)

Generation rate = f(time)

Biogas generation

Waste compositionTotal gas potential generation G°Somewhat the degradation rate

But, the degradation rate is much more influenced by landfill operation condition as water content, compaction and so on.

Measurement

Database

Page 12: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 12

Biogas generation/production

GENERATION

Theory

Total gas potential generation (m3 tons-1)

Reality

Total effective gas generation (m3 tons-1)

Only, a part biomethanized (40 - 50%)

CG *868.1

GG

Common value: C=225 kg C tons-1 G=189 m3 tons-1

COHERENT with literature

PRODUCTION

Total gas production (m3 tons-1)

r: recovery (%)

Gr *

GG *45.0

Total anaerobic degradation of organic carbon

Page 13: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 13

Leachate composition

LEACHATE COMPOSITION linked to:• Waste (composition, component solubility)

• Parameters controlling biological activity

(water content, temperature, oxygen content, pH, …)

VARIATION with time Stabilisation

[T] annéesen délai :

][ML source la deion concentrat :

10 : DBO

10 : DCO

10 : Chlorures

3-

043,05

0454,0

065,0

t

C

tCtC

tCtC

tCtC

o

tooo

tooo

tooo

Measurement

LITTERATURE

• BDO5, COD decrease = f(time)

• Stabilised waste prediction

• Database = f(landfill age)

Page 14: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 14

Hydrological balance Water inflow Rainfall

Evapo(transpi)ration

Run-off

Type of cover

Water inflow Leachate generated Waste stocks of water

Leachate generated Leachate collected Leachate remaining

Leachate infiltrated

Page 15: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 15

0.1

0.2

0.3

0.4

0.5

0.6

+ + + + + + + + + + +

Water inflow

Wat

er c

on

ten

t

Leachate flowrate

min

c

Water retention

max

Water retention

Water release

KINETIC

Page 16: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 16

Models & AWAST objectivesMatter balance

mean rates (database)Time consideration for more accurate prediction with measurements for

case study and calibration

Economical aspect NO

Energetic balanceBiogas recovered

Environmental balanceBiogas emissionLeachate exfiltration

Page 17: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 17

Landfill modelling

Aim of work

Methodology

What is a landfill ?

Models specifications

Conclusions

Page 18: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 18

Landfill models

2 inputs: Waste + Rainfall

4 outputs:

Collected leachate

Infiltration of leachate

Biogas emission to the atmosphere

Biogas recovered

(Run-off – evapo-transpiration)

2 aspects: Biogas + Leachate

Page 19: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 19

Biogas model(0)A fixed production rate 5.5 m3 ton-1 year -1 for 75% recovery

55% CH4 - 45% CO2 - pollutants ?

Calculation of mean production rate

History of landfilling

Lag time

Total gas production /ton

GT

nQwQb *

* 1 dntT

5.5

Gt

Where:Qb: average flowrate of biogas production (m3/year)

Qw: flowrate of waste deposited per year (ton/year)n: duration of deposition (years)G: total production of biogas per ton of deposited waste (m3/ton)T: Total time of release (years)t: time of release for each ton (years)d: lag time (years)

Page 20: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 20

Leachate - Model (0)Calculation of water inflow

= f (type of cover, total rainfall per year)

Calculation of exfiltration

1- Passive: clay - K=10-9m/s

2- Passive and active =f(holes in geomembrane)

NO calculation of generated leachate collectedDarcy law

No top cover(operating landfill) P*6.0

Simple top cover(naked soil)

P*4.0

Mid-permeable top cover(permeability typically between 10-8 and 10-6 m/s)

2100*)224*48.0(*12 P for aslope of 2 to 5%

Non-permeable top cover P*2.0 at least in mid term

Page 21: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 21

Leachate - Model (0)

Landfill age(years)

DCO(mg/l)

DBO5

(mg/l)NTK(mg/l)

1 year 15000-30000 5000-10000 1500-20001-3 years 8000 2000 15003-10 years 5000 1000 1000 10 years 2000 400 500

Composition Database

Page 22: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 22

Parameters - Model(0)Filled section

1: Area (m²)

2: Useful Height (m)

3: Density (m3/ton)

4: Top cover type (Simple, Mid-permeable, Impermeable)

5: Bottom cover type (Passive, Passive and active)

6: Recovery of biogas (%)

Active section

7: Area (m²)

8: Age of the landfill section (years)

9: Bottom cover type (Passive, Passive and active)

10: Total rainfall per year (mm)

11: % of biodegradation (hidden parameter)

Page 23: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 23

Biogas model(1)

t: time (from the landfilling)

G: effective gas production (m3 ton-1)

gmax: maximum gas production rate (m3 ton-1 year-1)

tmax: time of maximum gas production rate (year)

k*: biodegradation coefficient (year-1)

max1max *exp* ttkgg

ttkgg max*

max *exp*

Gkg **max

max

max

1

01.0ln

t

g

k

According to waste composition

Parameters - Adjustement parameters

Page 24: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 24

Biogas model(1)Specific gas production rate (m3/year/ton)

0

1

2

3

4

5

6

7

8

9

0 10 20 30 40 50 60

Page 25: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 25

Leachate model(1)Hydrological balance

P Rainfall

Collected leachate

Infiltration

ETP Evapo-transpiration

Run-off

Water inflow

Top cover

Bottom coverRemaining leachate

S: Stock of water contained in waste

RU: Stock of water contained in soil layer

ETR = k*ETPk (type of plant)

RUmax (type of soil)

k ’

Permeability DataAim of calculation

Page 26: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 26

Collected leachate

• Calculation of input water for waste water retention (Cp)

• Calculation of waste water content from water input and waste input• Calculation of water release

Leachate model(1)

If WC > WC c, then cd

WCWCt

WC

d

dT

2ln

Where:

Td: Time of midterm release (month)

WC: waste water content

WCc: critical water content

Adjustement parameters

Page 27: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 27

CONCLUSION

REMAINING TO DO:• Leachate composition - Model (1): Database?• Biogas valorisation• Economic aspect• Finalisation

Page 28: Progress Meeting - Rennes - November 2001 1 LANDFILL MODEL SPECIFICATIONS Fifth Framework Program Progress meeting Rennes, November 27-29, 2001 Progress

Progress Meeting - Rennes - November 2001 28