Compostable

Composting is the management of organic waste materials to create a soil amendment. The process of composting can vary from passive, where organics are simply piled together; to active, where materials are carefully managed to maintain specific carbon-nitrogen proportions, aerated to ensure ample oxygen availability and heat to maintain thermophilic temperatures. There are various methods of compost management and all materials that are intended for discard into composting should biodegrade in the specific management style used by the operator of the facility.

Most often, when a product is referred to as "compostable" it is expected to biodegrade effectively in a highly managed thermophilic compost system. Many compostable plastics do not effectively biodegrade in less managed or lower temperature facilities. (Typically compost facilities that accept food or animal waste operate at around 130-160F for at least a portion of the time due to the regulations by the EPA to kill pathogenic microorganisms found within the human and animal waste.) It is critical when selecting the type of compostable plastic, that a user understand the management style of the compost systems in their region to maximize compatibility.

Based on published test reports, the period of time to have microorganisms to completly desintigrate compostable plastic takes up to 6 months using PLA from Natureworks LLC and typically 3 months using the combination of PLA and Polycaprolactone mixture from Novamont.

Rules on Composting
The ASTM D6400 testing standard had it's origin from compost facilities having obligations by State regulations to complete their composting windrows within a 180 day period of time within the United States. Inside of Europe the time frame is reduced to 90 days. This has proposed issues within the composting companies as most of the products made from PLA do not compost within the time frame that their facilities actually turn their compost to a dollar value.

The ASTM D6400 added value to the composting market so there would be a standard set for a time frame that was suitable for composting products. This allows composting companies to not be interfered with when generating income from waste sources like bioplastics made from corn or sugar.

Compost Facilities
Facilities that accept PLA are limited in the United States due to the restrictions on USDA organic compost. This restriction greatly reduces the ability for compostable plastics to have facilities that compost bioplastics.