Page 263 - Materials Chemistry, Second Edition

L1644_C06.fm Page 236 Monday, October 20, 2003 12:06 PM

are the N pollutants of the eco-technology matrix. The eco-matrix may always
contain a part of potential environmental loads if accidents have been considered.

6.5.6 FATE AND EXPOSURE ASSESSMENT AND CONSEQUENCE
ANALYSIS
The level of detail in the fate and exposure assessment depends on the determined
importance of the respective process. The few processes that contribute most to the
overall environmental impact should be assessed on a site-specific basis, if possible;
other important processes can be evaluated by corresponding region-dependent or
technology-dependent impact assessment factors published in the literature (e.g.,
Krewitt et al., 2001). For airborne pollutants due to transport processes, an evaluation
based on site-dependent impact assessment by statistically determined factors for
generic classes seems to be most adequate. Nigge (2000) has proposed such a
method; in this study it was further developed and applied to the case study explained
in Chapter 7. However, it still must be considered as an approach in development.
Figure 6.14 gives an overview of the fate and exposure and consequence analysis
with the different levels of detail. The results of this analysis are the basis for the
damage-assigning matrices.
For the processes identified as most important, a site-specific or site-dependent
assessment is carried out if the site is known. If this is not the case, the corresponding
process must be treated as those processes are that have been determined to be
evaluated process- and/or region specified by literature values. If the site is known,
the data about the emissions in the LCI must be divided into upstream-related data,
which must be evaluated by literature values, and the foreground process-related
data or local emissions.
Only the obtained local emission data can be further assessed. If potential
emissions due to accidents are taken into account in the LCI and the eco-technology
matrix, in each case the kind of emission (continuous or one time) for a site-specific
assessment must be checked. An example of a site-specific assessment of continuous
emissions (the ERA and the IPA) carried out for Tarragona’s MSWI as described in
Chapters 4 and 5. An example of a one-time emission is that from an explosion.
Once a site-specific impact assessment has been carried out in a region and in this
way site-specific factors have been estimated, the results can be transferred to another
process in the same region, using a transfer factor, if necessary, for the stack height,
as proposed by Rabl et al. (1998) in the VWM (see Chapter 3). Such a transfer is
the use of results of the site-specific impact assessment of Tarragona’s MSWI for
another process within the region, e.g., for the ash treatment operation situated in
Constanti, a few kilometers away from the municipality of Tarragona.
If site-dependent impact assessment factors according to the approach outlined
in Chapter 7 are available, then these factors allow estimating the environmental
damages due to airborne emissions in the way of an adequate trade-off between
accuracy and practicability. This holds true especially for transport (tkm) because it
can be considered to be a number of industrial processes that take place (at one time
after the other) in different regions. Through site-specific and site-dependent impact
assessments, physical impact parameters are obtained that can be converted into

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