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2.2 Aerobic Biodegradability Analysis
The biodegradation process of plastic materials under aerobic conditions can be summarized
by the following reaction:
The basic driving force of biodegradation is the action of microorganisms, in the presence of
oxygen, using the carbon (C) bound in the polymer as a feedstock, breaking down the organic
matter into simpler compounds, such as carbon dioxide, water, mineral salts and new
microbial cellular constituents (biomass). The biodegradation rate can be determined by
directly measuring the amount of CO
several challenges/issues regarding the analytical apparatus related to this procedure, as
described below:
-
Complex and expensive instrumentation. The system requires a pressurized-air setup
that provides CO
enough to create truly aerobic conditions through the test. Additionally, suitable
devices for measuring CO
analyzer or gas chromatograph, are needed.
-
Depending on the analytical instrument applied (e.g., gas chromatograph), it may be
necessary to add a cooling unit to remove water from the air.
-
Oxygen levels must be closely monitored and controlled during the test, especially if
adjustments of the air-flow rate are made.
-
Usually, taking into consideration the limit of quantification of CO
concentration of test material is required in order to yield enough carbon dioxide for
the determination. In this way, big reactors are required for the test, which affect the
size and properties of the incubation unit which is used for temperature control.
Alternatively, BPC Blue Aerobic System provides a simple, efficient, precise and accurate
method for determining the biodegradation rate of polymers under aerobic conditions. This
volumetric respirometer continuously measures oxygen consumption resulting from CO
production throughout the entire experiment, providing real-time information on the
dynamics of the biodegradation process, including kinetic information and degradation
profile.
This system requires a small amount of test material and aerobic inoculum (e.g., 1 g test
material per 100 g inoculum), where dynamic or static incubation (with and without mixing)
can be applied depending on the type of fermentation medium considered for the test. BPC
Blue Aerobic operates based on the mechanism illustrated below (Figure 7):
C
+ O
CO
polymer
2
evolved as a function of time. However, there are
2
-free, H
O-satured air to each reactor at accurate flow rates high
2
2
and O
2
2
+ H
O + C
2
2
biomass
concentrations, such as continuous infrared
sensors, a high
2
2
15
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