Summary and conclusions, Miljøstyrelsen

Etablering af praktisk anvendelige procedurer for accept af affald på deponeringsanlæg

Summary and conclusions

Waste sorting tests were carried out at three waste disposal facilities. Mixed waste was sorted because the knowledge of materials in mixed waste is limited. Altogether, 13 truckloads of waste were sorted, and in this way, the most common materials in mixed waste were observed.

A simple method for observation of the waste materials is described for truckloads with more homogeneous waste. In this way, it is possible to gain knowledge of a significant part of the waste for disposal.

A preliminary analysis of the leaching characteristics of the waste for disposal was made. The collected data includes data on leachate quality at landfills.

A model for calculation of the outlet of leachate into the nearest recipient was prepared for a typical landfill.

The collected data was listed in a catalogue that can be supplemented with new data in the future.

Results of the project

Waste sorting tests

Sorting tests were conducted of mixed waste from recycling stations, industries and the construction sector. The truckloads for sorting were selected from the largest waste generators. One to three containers were selected at a time, and in this way, the sorting took place during a whole workday.

The sorting method was designed to be practical and usable. The homogeneity of waste in a truckload was visually evaluated. For the more homogeneous truckloads, only 1/3-1/2 was sorted and a maximum of three hours was spent sorting a truckload of waste.

First, the truckload was sorted by a machine and then manually. Other types of equipment used were containers, weighing machines and personal protection equipment.

13 truckloads of mixed waste were sorted at the three landfills, and the average waste composition observed is shown in the table below (see next page).

The sorting tests have provided knowledge of the composition of the mixed waste. The remainder after the sorting constitutes approx. 50% of the mixed waste for disposal. Therefore, it will be difficult in practice to sort and describe more than half of the mixed waste.

The remainder fraction consists of small parts with a diameter of less than five centimetres, and it is difficult to describe which materials it includes. In general, the remainder fraction will consist of small parts of the other waste fractions observed during the sorting tests. Furthermore, the waste fraction can consist of many small materials such as sweeping waste, dust from floor grinding etc. which cannot be visually observed during a test.

Average composition of mixed waste observed in the 13 truckloads of waste for landfilling.

No.	Waste fractions in mixed waste at landfills	Average for waste from industries and the construction sector (no. of sorted truckloads: 9)	Average for municipal waste (no. of sorted truckloads: 4)	Total average for 13 truck- loads
1	Cardboard and paper	3.4 %	5.7 %	4.0 %
2+3	Soft+hard plastics	4.8 %	7.4 %	5.5 %
4	Metals	4.0 %	0 %	3.0 %
5	Mineral wool	1.2 %	6.1 %	2.4 %
6	Wood	5.7 %	16.3 %	8.4 %
7	Flamingo, etc.	0.1 %	0 %	0.1 %
8	Textiles, carpets, etc.	0.5 %	3.3 %	1.2 %
9	Rubber/tyres	0.4 %	1.3 %	0.6 %
10	Electronics	0.1 %	0.2 %	0.2 %
11	Asphalt roof paper	4.1 %	5.4 %	4.4 %
12	Stone, concrete, glass etc. (inert/mineral)	11.4 %	0 %	8.6 %
13	Components of more materials (i.e. furniture)	7.0 %	3.6 %	6.1 %
14	Remainder (after sorting)	48.6 %	49.8 %	48.9 %
15	Plasterboards	3.1 %	0.3 %	2.4 %
16	Concrete and wood (composite)	1.4 %	0 %	1.0 %
17	Linoleum	1.9 %	0 %	1.4 %
18	Garbage	2.2 %	0 %	1.6 %
19	Eternit, roofplates	0.02 %	0 %	0.01 %
20	Ventilationpipe	0 %	0.6 %	0.2 %
21	Madras	0.1 %	0.1 %	0.1 %
	Total	100 %	100 %	100 %

Truckloads with mixed waste of a homogeneous character

Truckloads with mixed waste of a homogeneous character are defined as truckloads with less than three waste fractions. Many of these homogeneous truckloads were observed at the disposal facilities, and it was useless to conduct sorting tests of them. Instead, the truckloads were registered by use of the experience of the staff, and by this method between 12-16% of the materials in the mixed waste for disposal was described.

Leaching characteristics of the waste

It was possible to collect data from literature of leaching from gypsum waste, mixed inert waste, glass, street sweeping waste, sludge from waste water treatment plants, concrete, shredder waste, polluted soil plus various slags and ashes.

Model for calculation of leakage of leachate

Groundwater and recipient quality criteria were examined and a calculation model was prepared for the leakage of leachate from a typical Danish landfill. Calculations for four types of waste fractions were made by use of the model. The model is very sensitive to variation in the parameters describing the dilution.

The model can be utilized for identification of critical compounds at a specific locality of a landfill. The parameters describing the dilution must be estimated as carefully as possible by use of a risk assessment where the background level of the critical compounds is included.

Preliminary waste catalogue

The collected data is included in the catalogue. Data from leaching tests of waste is limited, and the catalogue should be updated with new data in the future. In the project, the catalogue is utilized for identification of critical waste fractions.

Practical and usable procedures for acceptance of waste at landfill

Practical and usable procedures for acceptance of waste at landfills including the use of the calculation model (leaking out of leachate) and the waste catalogue are described. Procedures for investigation of problematic waste fractions are described by use of the experience from the sorting tests and other activities of the project.

Main conclusions

The sorting tests conducted are usable and practical for the description of the composition of mixed waste for landfilling.

Because of the sorting tests, knowledge has been gained of the typical fractions in mixed waste for landfilling. It was observed that, in average, the remainder fraction after sorting was 50% of the mixed waste for landfilling.

A significant part of the mixed waste can be described by use of the registration of waste materials in truckloads with mixed waste of a homogeneous character.

Data from literature describing leaching characteristics, observations from the sorting tests etc. was collected in a waste catalogue. Data was not available for many important waste fractions such as the remainder fraction (after sorting), plastics, mineral wool, asphalt roof paper etc. New data should be added to the catalogue in the future.

Critical waste fractions can be identified by means of the waste catalogue. Waste fractions such as the remainder fraction (after sorting), plastics, mineral wool, asphalt roof paper, linoleum, textiles, plasterboards in mixed waste for disposal at landfills are identified as critical.

A practical and usable procedure for the acceptance of waste for landfilling can include the use of the waste catalogue and the calculation model - tools that have been developed in this project.