Characterization of Waste and Waste from old landfills

waste biological stability

Article 5(2)(c) of Landfill Directive 99/31/EC

• Moisture content; • Volatile solids;• Respiration tests the Respiration Index provides indirect

information on the presence and quality of the biodegradable matter in the waste sample

• Fermentation tests provide an evaluation of the potential biogas production in the landfill

• Leaching tests provide information on the attitude of the waste sample to release contaminants in the leachate;

• Black index test (BI)

Possible tests/parameters for waste characterization

Drill excavation from an old landfill

Waste excavated from an old landfill

The Respiration Index provides indirect information on the presence and quality of the biodegradable matter in the waste sample

Respiration tests – Respiration index

RI4 = 5 mgO2/gDM for stabilized waste;

RI4 = 80-150 mgO2/gDM for fresh waste);

Personal Computer

Control System Reactor

O2

GeneratorManometer

Scheme of the equipment for the measurement of the Respiration Index

RESPIROMETER: Thermostatic Bath and Reactors

0123456789

10

0 10 20 30 40 50

(mgO2/gST)

Pro

fond

ità (

m)

Example: Respiration Index for waste at different depths in landfill

RI4

Dep

th

0

15

30

45

60

75

90

105

120

0 1 2 3 4 5 6 7 8 9 10t(d)

mg

O2

/g

ST

BTi1

BTm1

BTf1

0

20

40

60

80

100

120

140

160

180

0 1 2 3 4 5 6 7 8 9 10t(d)

mg

O2/g

ST

BTi2

BTm2BTf2

0

20

40

60

80

100

120

140

160

180

0 1 2 3 4 5 6 7 8 9 10t(d)

mg

O2/g

ST

BTi3

BTm3BTf3

Example: O2 consumption in Respirometer

Sieving

Sample preparationShredding

GB21 <10 - 20 Nl/kgDM for stabilized waste

GB21 < 100 - 200 Nl/kgDM for fresh waste

This index provides an evaluation of the potential biogas production in the landfill

Fermentation tests

Fermentation Test

0

10

20

30

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50

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80

90

100

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

t (d)

Nl/k

gS

T

DC1DC2DC3DC4

0

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75

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105

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135

150

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95t (d)

Nl/k

gS

T

TQ2

TQ3

TQ4

Biogas production in Fermentation Test

0

10

20

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40

50

60

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

t (d)

% v

ol

CO2-DC1CH4-DC1CO2-DC2CH4-DC2CO2-DC3CH4-DC3CO2-DC4CH4-DC4

0

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60

70

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95t (d)

% v

ol

CO2-TQ2

CH4-TQ2

CO2-TQ3

CH4-TQ3

CO2-TQ4

CH4-TQ4

Gas Composition during a long fermentation test

The black index is a simple parameter that provides an indication of waste biological stability based on the observation of the change of colour of a lead acetate test paper.

Lead acetate paper is commercially available as strips madeof filter paper impregnated with lead acetate. The lead acetate on the test paper reacts with the hydrogensulphide yielding black lead sulphide as precipitate on the testpaper.

The colour of the test paper thus changes from whiteto brown, gray or black, depending on the concentration ofhydrogen sulphide in the atmosphere near the lead acetatepaper and on the duration of the test.

Black Index

BLACK INDEX TEST BOTTLES

Leaching test in Jar test apparatus

Column Leaching Test

Example: Correlation between RI4 and GB21 values

R2 = 0,80

0

10

20

30

40

0 2 4 6 8 10 12 14 16 18 20

IR4 (mgO2/gST)

B21

(N

l/kgS

T)

G

R2 = 0,81

0

10

20

30

40

0 2 4 6 8 10 12 14 16 18 20

IR4 (mgO2/gST)

BI (

d-1kg

-1)

Example: Correlation between RI4 and BI values

Parameter Waste Sample

S2b S3a

BOD5 (mg/l) 3 80

COD (mg/l) 67 1935

BOD5/COD 0,045 0,041

RI4 (mgO2/gDM) 1,9 7,8

GB21 (Nl/kgDM) 4,4 9,6

Example: Relevance of the BOD-COD ratio