On Feb 01, 2011 the Biodegradable Products Institute released its biodegradation test results of Aquamantra’s ENSO Biodegradable PET Bottle. BPI which is an industry organization for compostable plastics had the biodegradation tests performed by the highly recognized NSF laboratory.
NSF conducted the biodegradation test of Aquamantra’s biodegradable PET bottle, using ASTM D 5511 Standard Test Method. The ASTM D5511 is a standard test method for determining anaerobic biodegradation of plastic materials under high-solids anaerobic-digestion conditions”.
This ASTM Test Method calculates the amount of carbon dioxide and methane produced during the testing period. The cumulative amount of carbon dioxide and methane evolved from each vessel is calculated and compared to the amount of CO2 and CH4 evolved from blank specimens to determine percent degradation.
After 60 days, the Aquamantra ENSO bottle achieved an overall biodegradation total of 4.47% or 10% of the positive control. As part of the normal biodegradation process with this test method, the biodegradation process drops significantly for both the cellulose and plastic material, shown by the gas generation curve plateauing. Using the test results from this test of 4.47% biodegradation over 60 days and providing an environment with a steady innoculum the test material would fully biodegrade in approximately 3.7 years.
The Aquamantra ENSO bottle utilizes less than half of a percent of active biodegradable ingredients. In other words, the bottle BPI purchased in the market and used for testing was 99.5% PET and .05% biodegradable additive material. Comparing the biodegradation of the Polyethylene material (.37%) the results clearly indicate that biodegradation by microbial assimilation of the ENSO bottle is happening at a rate 8x more than the organic additive within the bottle. By moving the ENSO plastic into a new batch of innoculum biodegradation would continue to happen. There is no indication or scientific reason to imply otherwise.
There were a few notes to keep in mind about this test. The key to performing an effective ASTM D 5511 is in the proper preparation of the innoculum. Many labs are challenged when it comes to preparing a functional innoculum for this test. This is evident when the biodegradation rate of the cellulose material does not reach 70%. In the case of this particular test the cellulose material reached a maximum of 44.31%. Cellulose is a basic material that is normally biodegraded very rapidly and is used as a baseline to validate biodegradation. As stated by NSF, because there was clear biodegradation of the cellulose the the test results are acceptable even though the ASTM D 5511 required minimum of 70% was not obtained.
As a final point; with beginning with a healthy innoculum, biodegradation would have been improved for both the cellulose and ENSO biodegradable bottle; thus resulting in an improved biodegradation timeframe. We recognize that the slower performing innoculum may in someways perform closer to a true landfill environment.