Compost controlled, biodegradability test

Figure 6-7 Biodegradation test of PLA and cellulose powders by ISO 14855-2 method using MODA instrument in controlled compost at 58°C. Reprinted with permission from [17].

HD values were synthesized by controlled acetylation of commercial PVA (HD = 99%) and submitted to biodegradation tests in aqueous medium, mature compost and soil by using respirometric procedures [121]. Reacetylated PVA samples characterized by HD of between 25 and 75% underwent extensive mineiahzation when buried in solid media, while PVA (HD = 99%) showed recalcitrance to biodegradation under those conditions. An opposite trend was observed in aqueous solution, in the presence of PVA-acclimated microorganisms. In... 

The biodegradation of the compostable materials was tested in a controlled experimental environment. The experimental setup for the laboratory experiment is based upon procedures outlined in ASTM D5338. The procedures to measure the gases were done with detectors as allowed in the ASTM standards. Each of the compostable materials was added to compost soil in a 5-liter glass-canning jar and placed in an oven maintained at 58°C. The room temperature was between 22 C and 2TC during the course of the experiment. The jar containers have a rubber seal on the top. 

Rudeekit et al. (2008) conducted a biodegradation test of PLA under wastewater treatment, landfill, composting plant and controlled composting conditions (see Table 7.12). The researchers found that the PLA sheets had noticeable white spots on the surface after a 1-month exposure to wastewater treatment conditions and the areas affected by the white spots... 

Laboratory test of biodegradability [ISO 14855 (controlled composting test or equivalent)]... 

CO2, a blank compost inoculum without an additional carbon source (polymer sample) is simultaneously tested under the same conditions. The CO2 content of the exhaust air of both vessels is compared. After subtracting the CO2 evolution of the blank inoculum, the CO2 evolution related to the test polymer is monitored and plotted as a biodegradation curve (see Fig. 1). Finally, the activity of the compost inoculum in the controlled composting test is validated using a cellulose reference instead of the polymer. In Fig. 1, the biodegradation curve of Ecoflex is depicted. After 80 days, 90% of the theoretical CO2 evolution is reached. Thus, Ecoflex is ultimately biodegradable according to the ISO standard for compostable polymers (ISO 17088), which requires 90% of the theoretical CO2 evolution within 180 days. 

The biodegradation of EnPol polymers was tested in a controlled laboratory composting test and showed that within 45 days a carbon dioxide evolution of more than 90% of the carbon present in the co-polyester was detected. 

D5338-92 Test method for determining aerobic biodegradation of plastic materials under controlled composting conditions n o... 

ASTM D5338,1998, Standard test method for determining aerobic biodegradation of plastic materials under controlled composting conditions. ASTM Standard D5338-98-el. American Society for Testing and Materials (ASTM), Philadelphia (PA), USA. 

Pagga, U., Beimbom, D.B., Boelens J., and De Wilde, B 1995, Determination of the aerobic biodegradability of polymeric material in a laboratory controlled composting test. Chemosphere 31 4475-4487. 

Proper methods for the preparation of test samples that can be used for the determination of the ultimate aerobic and anaerobic biodegradability of plastic materials in an aqueous medium, soil, controlled compost or anaerobic digesting sludge have been standardized. These should result in an improved reproducibility of the test results during the assessment of the biodegradability (79). 

ISO 14855-2-2012 Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 2 Gravimetric measurement of carbon dioxide evolved in a laboratory-scale test... 

The ISO standards 14852 and 14855 (88,89) have been recently revised in the form of ISO 14855-1 2012 (90). This standards describes a method for the determination of the ultimate aerobic biodegradability of organic plastics materials imder controlled composting conditions by the measurement of carbon dioxide evolved and the degree of disintegration of the plastic at the end of the test. 

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