M. Finkbeiner et al., THE FUNCTIONAL UNIT IN THE LIFE-CYCLE INVENTORY ANALYSIS OF DEGREASING PROCESSES IN THE METAL-PROCESSING INDUSTRY, Environmental management, 21(4), 1997, pp. 635-642
In 1986 degreasing processes in the German metal-processing industry c
ontributed about 70,000 t to the emission of chlorinated C-1 and C-2 h
ydrocarbons (trichloroethane, trichloroethene, tetrachloroethene, dich
loromethane). Measures aiming at the reduction of toxic emissions and
ozone depletion potential (ODP) may possibly lead to a shift of enviro
nmental impacts towards higher energy consumption, emission of waste w
ater, and Volatile organic compounds (VOC) with photochemical oxidant
creation potential (POCP). The present article concerns itself with a
life cycle assessment of the three main degreasing processes in order
to compare their integral environmental impacts with one another. This
is supplemented by presenting the methodology of the life cycle inven
tory life cycle inventory analysis (LCI). Generally, the applicability
of the established LCI method can be shown quite clearly. However, so
me difficulties arise, especially at the stage of the goal definition,
as the use of the process and the functional unit cannot be pinned do
wn as easily and neatly as for most other products. The definition of
the use of the process and the functional unit is not as straightforwa
rd as for most products. Among the potential functional units identifi
ed are the mass of removed impurities, cleaning time, cleaning work, p
ercentage of purity, throughput of parts, loads, mass or surface and v
irtual coefficients. The mass of removed impurities turned out to be t
he most suitable parameter for measuring the technical performance of
degreasing processes. The article discusses background, purpose, scope
, system boundaries, target group, process tree and representativeness
of the present study.