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Chapter 02: BPC Blue Configurations and Components
2.1 Anaerobic Biodegradability Analysis
Under anaerobic conditions (absence of oxygen), biodegradable materials are converted into
methane (CH
), carbon dioxide (CO
4
Anaerobic biodegradability analysis is based on biogas (CH
different types of environment, such as aqueous medium, controlled slurry digestion system
and high solid digestion conditions. In this case, the biodegradation rate of plastic materials
is measured by a combination of evolved carbon dioxide and methane gases as percentage of
the conversation of carbon in the plastic sample to carbon in the gaseous form.
The first step in calculating the biodegradation rate of the investigated material under
anaerobic conditions, is to determine the amount of gaseous carbon (C
reactor. Using the ideal-gas equation, the volumes of CH
at standard conditions of temperature (273 K) and pressure (1 013,25 hPa):
Where,
p is the pressure in hectopascal (hPa)
V is the volume in L
T is the temperature in Kelvin (K)
The volume of biogas evolved needs to be adjusted to determine the corresponding amount
of gaseous carbon released, employing the standard equation: 22,4 mL of biogas at standard
conditions = 12 mg of C
The recorded volumes are also adjusted to account for variations in water vapor pressure and
atmospheric pressure that may have occurred during the test.
To calculate the average net amount, in grams, of gaseous carbon released during the
anaerobic biodegradation of the test material, subtract the average amount, in grams, of
gaseous carbon evolved in the three replicates of the test material from the average amount,
in grams, of C
evolved in the blank samples (three replicates). The biodegradation rate can
g
be calculated using the following equation:
), water (H
2
C
CH
polymer
4
.
g
O) and biomass:
2
+ CO
+ H
O + C
2
2
biomass
+ CO
4
2
and CO
4
) measurements considering
) evolved from each
g
are converted to volumes
2
8
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