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Fig. 3.6.1.
Mineralization of DEHP, pyrene and simazine measured as 14 CO 2 in the reactor
exhaust air.
microbial populations of ripe composts possessed considerable capabilities
to mineralize PAHs.
Other organic volatiles were observed to < 0.1% of initial
14 C-radio-
activity only.
Distribution in the compost matrix
[ 14 C]DEHP
Figure 3.6.2 shows the distribution of 14 C-radioactivity in the compost
matrix at different stages of composting. The main portion of radioactivity
was solvent extractable and identified by HPLC analysis as [ 14 C]DEHP.
The amount of water-extractable radioactivity was too small for the HPLC
analysis. Most probably metabolites were present in the aqueous extracts,
as was found by Weber (1989). The remaining NERs showed a slight
increase with time. Considering the loss by mineralization and applying the
data to the initial content of 14 C-radioactivity, the following values were
calculated: the water-extractable radioactivity did not exceed 4% of the
applied radioactivity at any time during the experiment. The NER fraction
amounted to 1.5% of applied radioactivity after the thermophilic phase and
increased to 1.7% after 200 days of composting.
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