Environmentally friendly products for events, restaurants and everyday use are rapidly growing in popularity, and (we hope) will soon replace plastic as the standard for all of our disposable needs. Biodegradable or better yet, compostable plastics are a more intelligent choice compared to petroleum based plastics for most everyday uses. Here's the dirt on understanding the difference between biodegradable and compostable products!

Defining the Differences: Compostable vs. Biodegradable

American Society for Testing and Materials (ASTM) defines a biodegradable plastic as "a degradable plastic in which the degradation results from the action of naturally occurring micro-organisms such as bacteria, fungi and algae."

A compostable plastic is defined by ASTM as "a plastic that undergoes biological degradation during composting to yield carbon dioxide, water, inorganic compounds and biomass at a rate consistent with other known compostable materials and leaves no visually distinguishable or toxic residues."

In other words, a compostable plastic must also be biodegradable, but a biodegradable plastic need not be compostable. Compostability requires the plastic to biodegrade into an in-distinguishable (as plastics) non-toxic matter, whereas a biodegradable plastic simply has to have the ability to biodegrade.

Compostability is a desirable feature in traditionally-disposable products such as plates, bowls, cups and cutlery. These products are commonly made out of PLA (Polylactic acid), bagasse (sugarcane fiber) or vegetable starch. It is environmentally-preferable to use disposable products that are labeled 'compostable' rather than just 'biodegradable'.

And while we're on the topic, here are some related terms you should know:

	Bioplastic (PLA): Made from corn starch, these products can be clear or opaque in color, look and feel similar to plastic but biodegrade easily and do not leach harmful chemicals.
	Bioplastic Compostable Cold Cups		Compostable PLA Cutlery		Compostable PLA Straws

	Sugarcane Fiber (Bagasse): These are products made from sugar cane stalk fibers, a waste product from sugarcane plantations. Bagasse is a renewable natural resource that biodegrades easily and has a fibrous paper texture.
	Bagasse Food Containers		Bagasse Cups		Bagasse Containers

	Cellulose: Made from the cell walls of plants, this is both a renewable and biodegradable material.
	Cellulose Bags

	Recycled: Recycled products are made from manufactured materials that have been reclaimed and reprocessed to create new products - Glass, aluminum, wood, and paper are among the most commonly recycled materials.
	Recycled Plastic Cutlery		Recycled Plastic Cups		Recycled Plastic Food Storage

Recyclable: Products that are recyclable refer to items that have the capacity to be recycled. Not all recyclable products are made from recycled materials or renewable resources.

Green Home Articles:

• Our Sustainable World: Composting


• San Francisco Passes Plastic Bag Ban


• Our Sustainable World: Recycling Plastics

Dig Deeper into Biodegradable

If something is biodegradable it has the proven capability to decompose into soil, water, carbon dioxide or methane gas within three years after being disposed of in an environment where it is allowed to break down. Biodegradable materials are generally made up from organic matters derived from plants, animals, and other substances originating from living organisms.

There are some disadvantages to biodegradable waste. When dumped into landfills, it is often dug under and trapped where the "good" bacteria can't survive to support the decomposing process. An example is human or pet waste, which is biodegradable, but can still be full of harsh chemicals, metals, and toxins. When biodegradable waste items are disposed of and sealed within a plastic bag, it prevents the natural biodegrading process and does not allow the material to decompose.

Biodegradable waste is an important substance due to its association with global warming. When it is disposed of in landfills, it breaks down under uncontrolled anaerobic conditions. This produces landfill gas which, if not harnessed, escapes into the atmosphere and contributes to global warming and the reduction of our ozone layer. Landfill gas contains methane, a more potent greenhouse gas than carbon dioxide. However, through proper waste management, biodegradable waste can be converted into energy by waste-to-energy processes such as anaerobic digestion and incineration. Anaerobic digestion is the process in which microorganisms break down biodegradable material in the absence of oxygen. As part of an integrated waste management system, anaerobic digestion reduces the emission of landfill gas into the atmosphere.

Dig Deeper into Compostable

Compostable products break down naturally into carbon dioxide, water, and biomass at the same rate as cellulose or paper (usually about 180 days) in an industrial or municipal composting facility. Compostable materials do not leave a toxic residue and cannot be distinguished from the rest of the compost after full degradation. It also needs to look like compost, should not produce toxic materials, and should be able to support plant life. Try composting in your own backyard. For more information on home composting click here.

Compostable products are biodegradable, but with an added benefit: when they break down, they release valuable nutrients into the soil, aiding the growth of trees and plants. These products degrade within several months in an industrial composting facility and produce no toxic residues.