What is the difference between biodegradable, compostable, and biodegradable plastic bags?

Traditional plastic bags
What harm do traditional plastic bags do to our environment? Let me do the math. Single-use plastic bags have an average lifespan of 12 minutes, and 2 million of them are used every 60 seconds worldwide. Polyethylene bags are made from non-renewable resources and are harmful to the marine environment because they are never biodegradable. Instead, they will break into smaller and smaller pieces over hundreds of years, causing countless damage to natural ecosystems.

Biodegradable plastic bags
In short, certain organisms are degradable when they are broken down by a certain organism, such as fungi or bacteria. Biodegradable bags are made with plant-based materials, such as corn and wheat starch, instead of petroleum. However, for this plastic, the bag must have certain conditions to start biodegrading. First of all, the temperature needs to reach 50 degrees Celsius. Secondly, the bag needs to be exposed to ultraviolet light. In a marine environment, it is difficult for you to meet one of the above two conditions. Plus, if biodegradable bags are sent to landfills, they break down without oxygen to produce methane, a greenhouse gas that has 21 times more warming power than carbon dioxide.

Biodegradable or "oxo-degradable" plastic bags
Biodegradable items do not have living organisms as a key part of the decomposition process. Biodegradable pouches cannot be classified as biodegradable or compostable. Instead, the chemical additives used in plastic make plastic bags break faster than standard plastic bags. Essentially, bags touted as "biodegradable" are absolutely unhelpful and even worse for the environment! After decomposing, the degradable bags will become faster and more microscopic, and even still pose a serious threat to marine life. Microplastics enter from the lower part of the food chain, are consumed by smaller species, and then continue up the food chain as these smaller species are consumed. Professor To·ny Underwood of the University of Sydney describes biodegradable plastic bags as "not a lot of solutions unless we're happy to convert them all to particle-sized plastic, rather than bag-sized plastic." 

Compostable plastic bags
The term "compostable" is incredibly misleading to the average consumer. You'd think that a bag labeled "compostable" meant you could put it in your backyard compost along with fruit and vegetable scraps, right? Mistake. Compost bags can be biodegraded, but only under specific conditions. Compostable bags need to be composted in a specific composting facility and are rare in Australia. Compostable bags are typically made from plant-based material, and when disposed of by these facilities, they revert back to their essential organic ingredients, but the problem is that so far there are only 150 of them in Australia.

Can I recycle plastic bags?
Plastic bags, biodegradable, biodegradable, and compostable bags cannot be placed in a standard recycling bin at home. If anything, they can seriously interfere with the recycling process. However, your local supermarket may recycle plastic bags. Some supermarkets can also recycle "green bags" that have been torn up or are no longer in use. Find your nearest location here.