Plastics : Biodegradable, Compostable, and Bio-Based Materials

The terms biodegradable, compostable, and bio-based are often mentioned when discussing environmentally friendly products. 

A product can be:

• Biodegradable without being compostable
• Bio-based without being biodegradable
• Bio-based, Biodegradable and compostable

1- Biodegradable plastic:

• Biodegradable material can be broken down naturally by microorganisms such as bacteria, fungi, and algae, converting it into water, carbon dioxide or methane.
• Being biodegradable is not an indication of  how long the process takes or under what conditions it occurs. 
• A biodegradable material may take many years to decompose if it ends up in an environment where microorganisms, oxygen, moisture, or heat are limited.

2- Features of biodegradable materials:

• Can be broken down by microorganisms.
• Eventually decomposes into natural substances.
• Decomposition time can range from weeks to years.
• Biodegradable does not automatically mean the material is environmentally friendly.
• May require specific environmental conditions to degrade effectively.

3- Features of a compostable material:

• A compostable material is a special type of biodegradable material. 
• It is designed to break down completely within a specific period under composting conditions, leaving no harmful residues or toxic substances behind.
• During composting, microorganisms convert the material into nutrient-rich compost that can be used to improve the soil quality. 
• To be compostable, a material usually must meet recognized standards that specify how quickly it should break down and what elements remain after decomposition.

4- Types of composting:

1- Industrial composting in facilities:

• Require high temperatures (often above 55°C)
• Require proper moisture levels
• Require adequate oxygen
• Require active microbial populations
• Allow compostable plastics to break down within a few months.

2- Home Composting:

• Home compost piles have lower temperatures and less controlled conditions. 
• Some products labeled "compostable" only decompose properly in industrial composting facilities and may not break down in a compost bin. 
• Products specifically labeled "home compostable" decompose under home composting conditions.

5- Features of compostable materials:

• Always biodegradable.
• Break down under composting conditions.
• Leave no toxic residues.
• Produce compost for a healthy soil.
• Requires industrial composting if not suitable for home composting.

1- Bio-Based materials:

A bio-based material is made  from renewable resources:

• Corn
• Sugarcane
• Potatoes
• Cassava
• Wood
• Vegetable oils
• Agricultural waste

The term bio-based describes the raw material used not its ability to decompose.

2- Bio-Based Materials:

• Made from renewable biological resources.
• Reduce dependence on petroleum.
• May or may not be biodegradable.
• May or may not be compostable.
• Can have properties similar to traditional plastics.

3- A simple comparison:

6- Bio-Based, Biodegradable and Compostable:

1- PLA (Polylactic Acid):

• PLA is made from plant sugars such as corn or sugarcane.
• Bio-based: Yes
• Biodegradable: Yes
• Compostable: Yes (primarily in industrial composting facilities)

2- Bio-Based PET:

• Some bottles are made partly from plant-derived.
• Bio-based: Yes
• Biodegradable: No
• Compostable: No
• Raw material comes from plants, the finished plastic behaves like plastic.

3- Paper:

• Paper is made from wood pulp.
• Bio-based: Yes
• Biodegradable: Yes
• Compostable: Usually yes, if not coated with plastic or contaminated with chemicals.

7- Common misconceptions:

•  A product can be bio-based and  remain in the environment for many years if it is not biodegradable.
• Many biodegradable materials require specific conditions and active microorganisms to decompose.
• Compostable materials break down in composting systems. If discarded improperly, they may persist for a long time.

8- Important distinctions:

• Choosing bio-based products can reduce reliance on fossil resources
• Biodegradable waste doesn't just disappears, it needs specific procedure for waste management.
• The environmental impact depends on how the material is produced, how it is used, whether it is reused or recycled, and how it is managed at the end of its life.

9- Conclusion:

The terms biodegradable, compostable, and bio-based are often used interchangeably, but they describe different characteristics. 

• Biodegradable refers to a material's ability to be broken down by microorganisms. 
• Compostable refers to materials that biodegrade completely under composting conditions. 
• Bio-based refers to materials made from renewable biological resources, regardless of their  biodegradability.