What's the difference between compostable and biodegradable

Compostable bags
Compostable bags need a specific composting environment to decompose effectively. This usually means the right temperature (usually around 50-60 degrees Celsius), humidity (about 50-60%) and plenty of oxygen. Composting facilities, whether large industrial composting plants or home composting bins, are designed to create these ideal conditions. In this environment, microorganisms (such as bacteria, fungi, etc.) can multiply and function in large numbers. For example, some compostable bioplastic bags can be decomposed into carbon dioxide, water and organic fertilizer in professional composting equipment after a few weeks to months.

Biodegradable bags
Biodegradable bags have a wider range of decomposition environments. They can decompose in natural environments such as soil, water or marine environments. However, the decomposition rate can vary greatly depending on the environmental conditions. For example, in a warm, humid soil environment with active microorganisms, a biodegradable bag may decompose relatively quickly, but in a dry or cold environment, the decomposition process will become very slow. Bags made of plant fibers, such as those made from plant fibers, may take from several months to several years to decompose in soil rich in organic matter, depending on the type of fiber and soil conditions.

Compostable bags
When placed in the right composting environment, compostable bags are usually able to decompose in a relatively short and predictable time. Generally speaking, a good quality compostable bag may be completely decomposed in 3-6 months in an industrial composting facility. This is because the composting environment is artificially controlled and the activity of microorganisms can be carried out continuously and efficiently.

Biodegradable bags
The decomposition time of biodegradable bags is more uncertain. In ideal natural environments, they may decompose in a similar time as compostable bags, but if the environmental conditions are not ideal, such as in an environment with a lack of microorganisms or extreme temperatures, decomposition may take years or even decades. For example, some biodegradable synthetic material bags may persist for a long time and be difficult to decompose in low-temperature environments such as the deep sea where microbial activity is weak.

Compostable bags
When fully decomposed, compostable bags produce organic fertilizers, carbon dioxide, and water that are beneficial to the soil. These organic fertilizers can improve soil structure, increase soil fertility and promote plant growth. For example, compostable bags made of corn starch and other raw materials can be used as high-quality soil conditioners and provide nutrients for crops after decomposition.

Biodegradable bags
The decomposition products are also natural substances such as carbon dioxide, water and some inorganic compounds, but in some cases, some tiny fragments or chemical residues may be produced. In particular, some complex synthetic biodegradable materials may not decompose completely, leaving some small molecular compounds that are difficult to further decompose, which may have potential impacts on the environment.

Compostable bags
There are strict international and domestic certification standards. For example, in Europe, products that meet the EN 13432 standard can be identified as compostable products and can be affixed with corresponding certification logos. These standards have clear regulations on the degree of decomposition, decomposition time, heavy metal content, etc. of the product to ensure the safety and effectiveness of the product during the composting process.

Biodegradable bags
There are also relevant standards, but they are relatively complex and less unified. Different countries and industries may have their own biodegradation standards. For example, ASTM D6400 is one of the standards of the American Society for Testing and Materials for biodegradable plastics, but it is different from the compostable standard. Moreover, some products may claim to be biodegradable, but in fact may not meet strict environmental protection requirements, and consumers need to carefully distinguish.

Compostable bags
Usually made of natural organic materials, such as plant starch (corn starch, potato starch, etc.), cellulose (such as pulp) and some bio-based plastics. These materials can provide rich carbon sources and nutrients for microorganisms in the composting environment, thereby promoting the decomposition process. For example, compostable bags made of cassava starch have starch molecules in their ingredients that can be quickly decomposed and utilized by microorganisms.

Biodegradable bags
The material composition is more diverse. In addition to natural organic materials, some specially treated synthetic materials are also included. For example, some polyester biodegradable materials achieve biodegradability by introducing biodegradable chemical bonds or groups into the polyester molecular chain. Although these synthetic materials can be decomposed under certain conditions, the decomposition process and products may be more complicated than compostable bags made of pure natural organic materials.