A Scenario Model for the Generation of Waste
3. ISAG and the development in the amount of waste 1994 -96
According to public regulations, waste management facilities have to report the amount of waste received to the Danish Environmental Protection Agency (Danish EPA, 1993). Waste management facilities include waste incineration plants, recycling firms and landfills. The data in ISAG are based on information from these facilities (470 plants). ISAG includes the amount of waste grouped according to the geographical and economic sources, the type (whether it is domestic waste, garden waste, waste from industrial activities, etc.), the content (fractions like combustibles, non-combustibles, paper and cardboard, etc.) and waste management (incineration, recycling, etc.).
The categorisation used in the model is mainly the primary economic sources (i.e. excluding waste from management facilities) and fractions. In the case of a few very composite fractions such as "Various combustibles", however, the type contains some information about which economic activity generated the waste. This information (in addition to supplementary information from specific analyses) is used when, for instance, modelling generation of "Various combustibles" by households.
The amount waste for each of the fractions and sources included in the model is shown for 1996 in Table 3.1. Fractions 90-93 account for about 30% of the total amount of waste generated. Of the total excluding fractions 90-93, the major fractions are "Various combustibles" (31% of the total excl. fractions 90-93), "Various non-combustibles" (9%), "Concrete" (11%), "Asphalt" (8%) and "Other building/construction waste " (6%). It should be noted that the fractions "Various combustibles" and "Various non-combustibles" are very composite fractions, containing a mixture of other waste fractions. In contrast, the other fractions are relatively homogenous and are collected separately with the purpose of recycling or special treatment.
The sources, "Households", "Trade and services" together with "Manufacturing", and "Building/construction" each generate about 1/3 of the total amount of waste in fractions 9-75. About 2/3 of "Various combustibles" is generated by households and of the total amount of waste generated by households, "Various combustibles" account for about 2/3. "Various non-combustibles" is more evenly distributed among sources, although manufacturing accounts for about 40% of the total. In the case of the large composite fractions "Various combustibles" and "Various non-combustibles", waste collected as household and bulky waste is examined in detail in Sections 3.1 and 3.2. Specific analyses of the content of the fractions are available for these two sources but not for other sources. "Concrete", "Asphalt" and "Other building/construction waste" are mainly generated by the source "Building and construction" including demolition and road construction.
Development in the total amount of waste is shown apportioned by source in Table 3.2. It should be mentioned that the statistics are still under development and are becoming more complete, i.e. part of the development/increase in the amount of waste is due to expansion of the statistical base (through an increase in the number of waste management facilities reporting to the ISAG system).
About 260,000 tonnes of the increase in 1996 is attributable to firms reporting for the first time. Of this about, 240,000 tonnes derive from the source "Building and construction". Correcting for this, the total amount of waste increased about 10% in 1996. As is apparent from Table 3.2, much of the increase is attributable to a considerable increase in waste from coal-fired power plants as a result of increased electricity production and the net export of electricity to Sweden and Norway. Correcting for the increase in the statistical base, the total amount of waste in fractions 9 to 75 increased about 8%. This mirrors a large increase in waste from building and construction (even when corrected for the additional firms included in the statistics) and moderate increases in waste from the other major sources. Waste from households increased about 6% with a large increase in garden waste and a small (2%) increase in the other fractions. Waste from manufacturing increased about 3%. Waste from trade and services increased about 2%. Thus correcting for extraordinary changes, waste from sources other than building/construction increased by an average of about 2-3% in 1996.
Table 3.2. Aggregated amounts of waste 1994-96.
The development in waste generation is shown for aggregated fractions in Table 3.3, and for all fractions and sources included in the model in Table 3.4. With regard to the sources, the development is partly attributable to extraordinary changes and the expansion of the statistical base. In the case of the major fractions the development has been as follows:
Table 3.3. Waste of aggregated fractions, 1994-96.
From Table 3.4 it can be seen that combustible and non-combustible household waste in 1996 totalled 1.8 and 0.164 million tonnes, respectively. This is a large share of the total amount of waste. Household waste consists of three fractions defined by the way it is collected: domestic waste, bulky waste and garden waste. The first two are analysed separately below.
The data for household waste shown in Table 3.4 include all household waste independent of the collection method. The amounts collected as domestic waste (in waste bags) are shown in Table 3.5. The fraction "Various combustibles" amounted to about 1.4 million tonnes in 1996, or 78% of the total amount of combustible waste from households (about 0.4 million tonnes were collected as bulky waste giving a total of about 1.8 million tonnes). In Table 3.5 the fraction "Various non-combustibles" represents waste bags from households, which have not been incinerated. In the future this fraction is expected to fall to practically zero. In the following, the fraction "Various combustibles" and "Various non-combustibles" are treated together as representing the total amount of combustible waste in the household waste bags.
Table 3.5. Domestic waste from household sources
In making projections it is assumed that the amount of each waste fraction is proportional to the future development of certain macroeconomic variables. Domestic waste is a too large and heterogeneous group of waste to relate to only one economic variable, however, and has to be disaggregated into more homogeneous groups of waste. As this is not possible based on the waste statistics available in the ISAG system, disaggregation has been undertaken on the basis of a specific analysis.
The best available analysis of household waste was carried out during a one year period from July 1992 to July 1993. A total of 2,650 waste units (bin-bags) from households, totalling over 25 tonnes of waste, were hand sorted into 20 different fractions (Danish EPA, 1994). Domestic waste from flats, houses (detached/semi-detached), terraced houses, farmhouses and summer cottages was analysed. Random samples of one weeks waste were taken at six different sites around Denmark. In order to gain an impression of any seasonal variations, one weeks waste from 50 selected houses was also analysed once a month over a full year. The conclusion, however, was that there were no notable seasonal variations.
The waste fractions weights determined in the analysis are based upon waste which has been mixed, i.e. water will have moved from the wet food waste into the paper fractions. The results were therefore adjusted for this water movement based on dry matter analysis. This correction for the water movement is included in Table 3.6. Thus 10% has been added to the weight of the vegetable food waste and the animal food waste, 10% subtracted from the weight of "Other soiled paper and cardboard" and "Other clean paper and cardboard", and 40% subtracted from "Absorbent household paper".
The amount of paper and glass collected through various schemes for recycling and reuse was also determined and corrected for in order to produce an overall picture of domestic waste generated. The results of the analysis are given on page 109 of Danish EPA, (1994). The fractions "Paper and cardboard" and "Bottles and glass" in Table 3.5 already include the amounts of paper and glass collected through the various schemes for recycling and reuse, however. Since we are here investigating the composition of the waste in the first two lines of Table 3.5, "Various combustibles" and "Various non-combustibles" (i.e. the content of domestic waste bags), we must exclude the correction for the recycling schemes. Only the waste paper in the household waste bags is included in Table 3.6.
The total amount of combustible and non-combustible domestic waste in 1996 was thus about 1.1 million tonnes, or about 0.3 million tonnes less than the data shown in ISAG (Table 3.5). One reason for this could be that part of the waste collected from households actually originates from the service sector. The difference between the figures in Table 3.6 and the ISAG data is mainly attributable to the fact that waste from summer cottages is not included in the calculations, however.
The right hand column in Table 3.6 shows the three macroeconomic drivers (Appendix 1) used to project the waste fractions (no driver for garden waste). Adding the fractions in these groups it is apparent from Table 3.6 that 65.8% of the content of the waste bags is food and packaging waste, 16.5% is paper and other non-durable goods waste, 13.8% is durable goods waste, and 3.9% is garden waste.
Table 3.6. Content of the combustible and non-combustible fractions of domestic waste in Table 3.5.
The amount of bulky waste from households registered in ISAG is shown in Table 3.7. The fractions "Various combustibles" and "Various non-combustibles" account for 85% of the bulky waste from households and the following analysis therefore concentrates on these two fractions.
Table 7 Bulky household waste registered in ISAG in tonnes.
As is apparent from the table, "Various combustibles" increased over the period 1994-1996, while "Various non-combustibles" decreased. The total amount of bulky household waste also increased during the period.
An analysis of bulky waste has been divided into combustible and non-combustible waste (see Danish EPA, 1998). The analysis has been made on randomly chosen loads of waste from different municipalities in Denmark in June 1996. Altogether 19 containers from 6 municipalities were analysed. The containers derive from manned container stations, unmanned container stations and collection systems. Although only bulky waste was supposed to be disposed of in the containers, all containers examined contained other waste such as domestic waste, garden waste and oil and chemical waste. In the following, the waste from the analysed containers is divided only into combustible and non-combustible bulky waste, ignoring other waste types incorrectly placed in the containers.
The fractions "Various Combustibles" and "Various non-combustibles" are characterised by being compounded fractions. Unlike the fractions "Paper and cardboard", "Bottles and glass", "Plastics", "Iron and metal", "Car tyres", "Concrete", "Tile/bricks", "Asphalt", "Wood", "Earth and stone", which all consist of rather clean materials, "Various combustibles" and "Various non-combustibles" are assumed to consist of a variety of different products and materials.
Bulky waste is reported to the ISAG system by the waste management facilities, and not by the municipalities. As the above-mentioned analysis has been made based on data registered by the municipalities, there may be differences in the data from this analysis and the data registered in ISAG.
The "Various combustibles" fraction was divided into the two groups; "Small combustible waste" and "Large combustible waste". Small combustibles are collected through collection schemes and at manned container stations for recycling, while large combustibles are only collected at manned container stations. However, the waste collected through collection schemes is delivered to the manned container stations and registered there. The public can dispose of bulky waste at manned container stations which typically have containers for paper and cardboard, bottles and glass, plastics, iron and metal, and for various combustibles and various non-combustibles. Only containers with combustibles and non-combustibles were analysed.
The distribution of combustible waste into different groups of products varies depending on the size of combustible waste, see Table 3.8. Based on the results of the analysis, the combustible waste has been weighted as 80% small waste and 20% large waste in the right hand column.
Table.8 Combustible waste apportioned by product type.
Furniture: 40% wood and textiles, 30% carpet.
Based on the weighed average, combustible waste from construction and demolition accounts for the major share of the combustible waste (36%), followed by furniture (33%) and packaging (17%). With respect to small and large combustible waste, however, the figures vary. For example, packaging accounts for 22% of the small combustible waste but only 3% of the large combustible waste.