Industrial Compost Environment

Region Performance specification Test method Measurement method Disintegration test method 

USA ASTM D6400, D6868 ASTM D5338 COj measurement ISO 16929 

1 Biodegradation Performance Specification Standard ASTM D6400-04. Standard SpeciBcation for Compostabie Piastics 

1 Summary This American specification standard establishes the performance requirements for biodegradation of compostable plastic materials that are designed to biodegrade into CO2, water, and biomass in an industrial compost environment. The industrial compost environment is one that maintains a temperature above 40° C and results in thermophilic conditions. The performance specification standard requires the use of ASTM D5338-05 test method to measure the amount of CO2 that is emitted from the degrading plastic sample. 

ASTM D6400-04 performance specification standard requires the product must demonstrate each of the three characteristics as follows  

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Starch-based plastics can be classified as compostable if the additives are also biodegradable under industrial compost environment conditions. Starch can be an additive for petroleum-based plastics like polyethylene, polypropylene, polyurethane, and polyester. However, these starch-filled petroleum-based plastics are not included in this book since they would not biodegrade under industrial composting conditions and would not be recyclable with commercial mechanical recycling operations. 

Biodegradation is an important feature of biodegradable plastics. Two essential components of the biodegradation process are that the material must be a food source for the bacteria in the disposal environment and that the biodegradation must take place within a short time period, typically 6 months. Therefore, biodegradation can occur in an industrial compost environment for biodegradable plastics if they are used as food source for the bacteria in the compost and that they are... 

This chapter describes the worldwide biodegradation standards for biodegradable plastics, including starch-based plastics, in common disposal environments, including compost, marine, anaerobic digestion, soil, and landfill. Compost environments include aerobic conditions within hot industrial compost environments. Marine environments include cold aerobic conditions. Landfill disposal environments include aerobic and anaerobic conditions. Anaerobic-digestion environments include hot anaerobic conditions. 

International Biodegradation Standards for Industrial Compost Environment... 

Biodegradation standards for industrial compost environment require a biodegradation specification standard and a biodegradation test method standard. The specification standards in Europe are for plastics and for packaging. Both specification standards require the use of the same test method. 

The test materials used are all commercially available plastics that are made from corn, namely, polylactic acid (PLA) and polyhydroxyalka-noate (PHA). PLA and PHA materials have passed the ASTM D6400 compostability standard and biodegraded in a simulated industrial compost environment in 180 days. ASTM standards are applicable for plastic molded products and not plastic pellets. The samples for the ASTM D6691 test included the following ... 

Nevertheless, field trials in natural environments are still used to extrapolate results acquired in laboratory tests to biodegradation behaviour under realistic outdoor conditions " Recent German regulations for the assessment of compostability of plastics even impose exposure of the product to a full scale industrial composting process to ensure that total disintegration will occur in real-life waste-processing". ... 

It is not possible to provide a specific timescale in a general standard for oxo-biodegradable polymers, (as distinct from a standard for industrial composting) because the conditions found in industrial composting are specific and the conditions foimd in the open environment are variable. Also, the time taken for oxo-biodegradable plastic to commence and complete the processes of degradation and biodegradation can be varied. 

Solid waste disposal environments for plastic materials can include industrial compost, home compost, anaerobic digestion, landfill, litter, and ocean water. Only two disposal environments have both biodegradation standards for test methods and biodegradation performance standards, for example, industrial compost and marine biodegradation environments. Test method standards are available for anaerobic digestion, home compost, and landfill environments. The second necessary performance specification standard for biodegradation performance is not available for anaerobic digestion, home compost, or landfill... 

Biodegradation standards are provided in the following sections. The standards are organized based on disposal environment. Thus, the biodegradation standards from different worldwide standards organizations are presented in an industrial compost section, marine environment section, an anaerobic-digestion section, landfill section, and home compost section. 

Summary This international standard specifies a method for the evaluation of the disintegration of plastic materials while under industrial composting conditions. The testing environment is pilot scale at an industrial compost facility. The mass of plastic sample is measured prior to the test. The samples are placed in a sack or aerated bag with compost soil. The sack is placed in an aerated pile at least 1 meter deep at an industrial compost facility. The compost vessel should be a minimum of 5 liters and a maximum of 20 liters. The concentration is 1% by weight plastic sample and 99% compost. The temperature of the compost pile should be between 40°C and 75°C. The aerated compost pile should be turned twice per week. 

To be compostable the biomaterial requires a controlled microbial environment such as an industrial compost facility before they will degrade. This is because there are requirements of heat, moisture and aeration to activate and sustain the degradation process. To be considered compostable, a material must be able be put into an industrial composting process and breakdown by 90% within six months. Under the European Standard EN 13432 [2] they can be labelled or marked with a compostable symbol. 

An alternative is to use a biopolymer. In a similar film application for example, an option would be to use one that is starch-based and derived from corn (PCL, PVA or PLA). These biodegradable films, dependent on thickness, would meet the ASTM standard (American Standard for Testing Materials) and European [EN13432] for composting. However these materials require a controlled microbial environment such as an industrial compost facility before they will degrade. 

To he compostable a biomaterial requires a controlled microbial environment such as an industrial compost facility before they will degrade. 

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