This subsystem, defined for copper in the Netherlands in 1990, comprises scrap recycling, waste incineration, sewage treatment, composting and landfill. Not only but also industrial waste treatment is part of this subsystem. The input consists of the scrap and waste to be processed, the output of secondary resources and, possibly, completely immobilized or degraded Compost and sewage sludge constitute a separate category: to a certain extent these are reused in the agricultural sector as a fertilizer. However, one can ask whether this ought to be classified as a functional output. For metals, at any rate, it can be argued that this is in fact a leakage from the cycle: recycling in agricultural produce is undesirable, and any further functional use of the metals is out of the question.
Figure 4.7 Subsystem Waste Processing
Netherlands due to the absence of copper mines.
This subsystem has a leakage percentage of 28, and therefore a 72% efficiency which is much lower than the other
stages. The contribution to the total losses from the economic system is large: 89.8%. Both in a relative and in an absolute sense, the losses from the Dutch copper chain obviously occur in the waste stage. It should be noted that on a global level this need not be true: large losses are connected with the mining of copper, which do not show in the
It is also possible to consider splitting the economic system vertically — for example, the food production and consumption column, or one specific source and its destinations. It becomes possible to see the differences between the more or less separate cycles of applications that exist within the economic system: cadmium from zinc ore vs. cadmium from phosphate rock, applications of metallic copper vs. applications of copper compounds, copper in the agricultural system vs. copper in the transport system, and so on.
Interpretation for environmental policy
As a general rule, it can be stated that the higher the efficiency of the processes, the better it is. An efficiency of 100% therefore, although it can never be reached, may serve as a target. But there is more information to be extracted from this efficiency indicator. In the first place, the life- cycle stage which is responsible for the biggest losses can be identified. In various case studies, it has been shown that the largest leakages no longer occur in the production stage, but in the use or waste management stage, depending on the substance and the application. This also gives interesting insights into the behavioral characteristics of substances in the economic system, as is worked out in more detail in Chapter 6. Secondly, the efficiency per life-cycle stage provides a measure to compare different techniques or options for production, user behaviour and waste management. Thirdly, the efficiencies of different sectors within the economy can be compared. Finally, different substances can be compared, which may provide some policy relevant information as well. In the table below, the leakage percentages for six heavy metals in the Netherlands are presented.
A remarkable difference can be seen between the more bulky metals Cu, Zn, Pb and Cr on the one hand, and the small-scale metals Cd and Hg on the other hand. The losses from all life-cycle stages are much larger for Cd and Hg. Partly, this is due to the low recycling rate. It also may have to do with the relatively large non-intentional flows for Cd and Hg, which will be treated in more detail under Indicator 5. For lead, the recycling percentage is highest. For zinc, the low losses in the waste stage are due partly to a large export of waste, mainly scrap, to be treated elsewhere. It may be considered to follow the fate of exported waste and demand a correction to the losses from the waste stage accordingly. On the other hand, this is not relevant for the region's own waste management regime, which is the only waste management to be influenced by a region's policy. Theoretically, a region's policy could be directed (intentionally or not) at exporting this life-cycle stage and thus the pollution would be exported. This is discussed further under Indicator 7: problem shifting to other regions.
Table 4.2 from the economic cycle of six heavy (the Netherlands, 1990, % of input into each process
Metal Cu Zn Pb Cr Cd Hg Life-cycle stage Production/manufacturing Use/consumption Waste treatment 0 1 0 28 2 3 6 16 8 1 2 6 6 4 0 11 13 20 14 43 61 41 15 73
The may not be added to one overall percentage due to and the different of the life cycle do not connect.
Only recovery from and of iron, and ores (no the Netherlands)
Indicator 5: the relative magnitude of non-intentional applications
As stated above and treated in more detail in Chapter 6, it is very important for environmental policy to allow for the problem of non-intentional flows within the economic system, i.e. flows of the substance caused wholly or partly by forces other than the demand or need for the substance itself. may occur at all stages of the life cycle: recovery as an ore contaminant, or less extremely as a by- or co-product, application as a product contaminant, occurring as a non- functional or even unwanted trace in food products, or non-intentional recycling in waste residue materials. Shifts from intentional to non-intentional also occur: the cadmium, recovered initially as a by-product of zinc, is intentionally extracted from zinc ore and applied in batteries, while the intentionally applied pig feed copper additive ends up unwanted in slurry. In secondary materials such as manure, compost, fly ash, scrap and suchlike, there are often large quantities of pollutants unintentionally starting their second life cycle. While the intentional flows can be addressed more or less effectively by a policy directed at the intentional applications of the substance, this is less obvious for the non-intentional ones since the "normal" relationships of supply and demand cannot be applied to the substance any more. Moreover, the non-intentional applications often are of a rather dissipative nature and therefore are more at risk of leaking from the economic cycle to the environment unnoticed.
The significance of the indicator
The magnitude of the non-intentional flows vs. the intentional ones indicates the level of risk of measures directed at the substance will lead to an unsuspected shift of the problem, due to the fact that the (implicitly) expected and "downchain" relations are not present. In this case,