Stage 3

The urban waste, an inexhaustible source of energy, is an alternative for use in various fields. Besides garbage, it also contains waste from various fields of activity. The waste composition differs from one locality/area to another. An important issue is the fact that the waste is not sorted, and this can cause problems when it is processed. The waste contains significant quantities of non-combustible/non-biodegradable materials. The incineration of solid urban waste (SUW) is a thermal method of elimination by complete oxidation at high temperatures. Table 1 shows a classification and characterization of the various types of waste, and Table 2 shows the combustion conditions for various types of waste.

Crt.
no.

Waste /
Characteristics

H2O
%

Ash
%

Density
kg/m3

Caloric power
kcal/kg

1.

Type 0. Crumbled
Paper, boxes, wood, cardboard, garbage, < 10% plastic and rubber

10

5

128 - 160

4723

2.

Type 1. Pieces
Paper, boxes, wood, cardboard, garbage, < 20% food

25

10

128 - 160

3611

3.

Type 2. Refuse
Mixtures of the above plus food

50

7

240 - 320

2389

4.

Type 3. Garbage
Food, plant or animal remains

70

5

481 - 560

1389

5.

Type 4. Pathological
Human or animal remains

85

5

721 - 881

550

6.

Type 6. Compact
Documents, rubber, plastic, wood

 

 

561 - 801

4167

7.

Bark

10

3

192 - 320

5000

8.

Sawmill waste

10

3

160 - 192

4723

9.

Tyres

 

20 - 30

993 - 2000

5556

10.

Brown coal

3 - 12

4 - 36

1200 - 1400

3300 - 7200


Parameters

Wood

Urban waste

Dangerous

Humidity, %

55 - 60

30 - 40

20 - 35

Injector thermal duty Gj/m2h

8,5 - 11,4

3,4

5,7 - 8,5

Used O2 moles / necessary O2 moles (SR)

1,3 - 1,5

1,8 - 2,0

1,6 - 1,8

Air excess, %

25 - 30

80 - 100

60 - 80

Additional air, %

20 - 40

30 - 40

30 - 40


The objective of the project is the waste recovery by incineration and co-incineration respectively, as well as by obtaining biogas by means of anaerobic digestion. Table 3 presents the relative energy potential of biogas coming from various sources, in the process of obtaining biogas.

Biogas sources

Energy potential [TWh/an]

Landfill

6

 Communal and industrial effluents

 

Organic waste from households and markets

18

Industrial organic waste

 

Excrements

 

By-products from agriculture and food industry

47

Materials from landscape conservation

 

Planting of energy plants

141

Wood

187

Urine

4

Nutrients from effluents

5


Correlated with the topic, there have been made studies on two pilot installations, one for the co-incineration of urban waste, the other for obtaining biogas from urban waste by anaerobic digestion.

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