As shown in Fig. 1, industrial composting occurs when bacteria
and fungi degrade biomass under aerobic conditions and at high
temperatures (50e60C). Compared with home composting,
industrial composting not only reaches higher temperatures, but
the biomass involved is also mixed more frequently, thereby
ensuring a higher homogeneity and thus faster degradation of
biomass. The data for industrial composting used here is based on
eight data-sets on industrial composting, which all show similar
levels of biodegradation (see Table 6). Tables 6 and 7 also illustrate
that the carbon balance is not always closed for industrial composting.14
The data chosen for this study are in line with the latest
publications on industrial composting of vegetable, fruit and green
waste (VFG) in terms of methane and nitrous oxide emissions (see
[26,73,75] 15). Many more publications are available on industrial
composting (see e.g [8], for an overview), but most of these do not
specify carbon input and biogenic CO2 emissions from the composting
stage and therefore do not allow calculating a carbon
balance.
The GWP from industrial composting as calculated is dominated
by emissions of carbon dioxide. Emissions of methane are rather
exceptional and are small when they do occur and compared with
home composting, nitrous oxide emissions are much lower. We use
the results for process emissions from industrial composting of VFG
(see Table 6) and material-specific biodegradation levels (see
Table 2) to derive data for the biodegradable materials. The results
per kg material are shown in Table 11.