August 28

Biodegradable Vs. Compostable Trash Bags – Which to Use and When

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Maybe you already have a reusable coffee mug or some vegan leather sandals. If you care for the environment, you may have investigated the new and improved compostable and biodegradable trash bags.

While compostable and biodegradable bags are a critical part of helping to sustain our beautiful Earth, there are some important distinctions to be made. These two are not the same type of trash bags, and in order to make the best choices for the environment, you'll need know a few things. 

Below we’ll fill you in on the essential details about these two products, the best companies to follow, and the right way to use them.

Enjoy!


What's the Difference?


Compostable Trash Bags

Compostable trash bags consist of plant starch converted into bioplastics. Starch is easily broken down by microorganisms in soil and compost piles, just like any plant matter, and it does not produce toxic byproducts or contain petroleum-based plastics or heavy metals. These bags are intended to dissolve in a compost pile or, more often, in an industrial compost facility.

Biodegradable Trash Bags

Biodegradable trash bags come from petroleum-based plastic, so they feel and perform like a standard kitchen trash bag. But, unlike your classic trash bag, they are susceptible to digestion by the types of microorganisms living in landfills. These organisms break up the large chains of plastic into smaller chains of plastic.

At times, this is accomplished by the inclusion of heavy metals into the plastic. Some of the bacterial species thriving in the anaerobic landfill environment are those whose respiration depends on metals rather than oxygen, and they see these metal-infused plastics as a food source. 

The Main Differences

The most critical distinction between these two is the label. “Compostable” is a government-regulated industry standard in both the U.S. and Europe. 

Legally, this means that a product advertised under this label should break down under “compost conditions” into natural elements without leaving toxic byproducts in the soil within about 180 days.

The trick lies in the phrase “compost conditions,” which most people take to mean a home compost pile. In fact, for the purposes of labeling regulation, “compost conditions” means a high-temperature industrial compost facility

 The label “biodegradable” is entirely unregulated. Much like the label “natural,” it can mean almost anything an advertiser wants it to mean, rendering the label effectively meaningless.

How Quickly Do Compostable / Biodegradable Bags Degrade?


Biodegradable Trash Bags

In the presence of light, oxygen, and moisture, biodegradable trash bags may rot away within a few months. However, these conditions are rare.

Most of these bags find their way into a landfill, where light, air, and moisture are scarce. In this case, biodegradable trash bags break down no faster than standard trash bags. In a landfill, plastic is plastic!

Compostable Trash Bags

Any bag labeled compostable should deteriorate in a way similar to other plant matter within between 90-180 days if used as intended. Consumers may want to examine the label closely to make sure that the bag is marketed for “home use,” meaning it will break down without an industrial compost facility’s extreme heat.

In practice, many users find that the bags are markedly diminished but still visible in the compost pile after 180 days. In reality, it may take several seasons for bags to decompose fully. Lower pH and higher moisture and heat accelerate the process.

Common Misunderstandings


Are Compostable /Biodegradable Bags Recyclable?

Neither compostable nor biodegradable trash bags are recyclable. They should be sorted into the general waste bin or, in the case of compostable bags, used for compost material.

Do Compostable/ Biodegradable Bags Break Down in Landfills?

While it seems evident that these bags would degrade more quickly in landfills than standard plastic bags, in fact, neither of them usually breaks down well in a landfill.

EPA regulations require landfills to block out most oxygen, moisture, and sunlight. Without these crucial elements, very little decay of any kind is happening inside a landfill.

Although they are not sterile environments (studies show that aerobic, anaerobic, and sulfur-reducing bacteria are all present), reactions occur so slowly that using a biodegradable trash bag is similar to using a standard trash bag.

Both will take decades or even centuries to break down under typical landfill conditions. Compostable trash bags decay slightly more quickly, although some studies have found them still completely intact in landfills after three years.

Can Compostable/ Biodegradable Bags Harm the Environment?

All products labeled “compostable” or--even worse--“biodegradable” can be environmentally problematic because of the phenomenon of “greenwashing.”

Customers spot a claim on a label that assuages their concerns about the environment. Rather than attempting to use the product as directed or, indeed, take future environmentally conscious actions, the consumer may do further damage, such as over-using trash bags or even littering with them.

Cases of litter with compostable and biodegradable trash bags do exist, possibly stemming from the mistaken idea that these bags will break down and decompose like an apple core thrown out of a car window.

On the contrary; they are still plastic and should be used only in the intended manner. When scattered as littler, biodegradable and compostable bags disintegrate faster under the sun, rain, and air than a standard trash bag would.

However, they still break into thousands of tiny plastic bits that are consumed by animals and incorporated into waterways. In fact, by crumbling quickly into so many small pieces, these bags actually may do more harm than standard plastic.

Are They Worth it?


Consumers should expect spectacular functionality from biodegradable and compostable trash bags at prices two to five times greater than the standard item.

Most brands just don’t deliver results that meet the expectation. Compostable bags have limited kitchen use (they don’t tolerate wet or heavy loads well), and biodegradable bags make empty promises.

With brand names like “EarthHero” and “If You Care,” these green-washed products push the environmental guilt hard. We recommend compostable bags.

At a minimum, its plastics are made from short-term carbons, and it will dissolve quickly and to non-toxic bioplastics in the ocean (if that is where it ends up, as so much plastic does). Plus, when it (eventually) breaks down, it will make CO2 instead of methane, a more potent greenhouse gas.

Best Compostable Trash Bags


For Large Jobs 
(Like Collecting Leaves and Yard Clippings)

Envision 33 Gallon Compostable Trash Bags

For Smaller Jobs
(Countertop Home
Operations)

ProGreen 2.3 Gallon Compostable
Trash Bags

Why These Brands?

Composting bags are generally not strong enough to hold heavy loads. They begin to dissolve under contact from any moist, acidic, or microbially-rich trash (think banana peel, old strawberries, coffee grounds, etc.). While some brands may need to be changed every couple of days, the brands above are well-reviewed for having an above-average “lifespan.”

Before You Buy

In addition to its intended purpose of lining a kitchen composting bucket, a compostable trash bag will probably serve well for an area that is changed frequently and holds dry, light loads, like a desk or bathroom (especially if these loads are also compostable).

Although many composting bags come in a 13-gallon size, none are listed here. Since 13-gallon is a standard size for regular kitchen trash, a composting bag used this way would end up in landfill -- not a practical or intended use for these bags.

Best Biodegradable Trash Bags


Trash Bags

Eco Smart 13 Gallon Trash Bags

Why This Brand?

Although some websites claim that Eco Smartbags are compostable, they are not. However, what makes these biodegradable bags interesting is their inclusion of a proprietary additive (recall that this may or may not include heavy metals).

This compound hastens the action of anaerobic bacteria in landfills; the company claims that a bag will decompose in a landfill within seven years (not third-party verified). If this is true, their “biodegradable” claim is more accurate than most. 

Before You Buy

These bags are probably more appropriate for typical kitchen use, both because they claim to break down in a landfill (compostable bags won’t) and also because they can comfortably hold wet, heavy loads for long periods without risk of breaking.

Conclusion


The next time you see the marketing labels “compostable” and “biodegradable” in the grocery store, you will know the differences between them and when each one is best used. You’ll know what to expect, and you can make an informed decision for your lifestyle.

If you have any questions or comments, leave them below.

Cheers,

Caitlin


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About the author

Caitlin is a Ph.D student and chocolate researcher at Colorado State University. Her research in the Food Science program focuses on chocolate fermentation (that’s right, it’s a fermented food!) and small-batch post-harvest processing techniques. When she is not acting in her capacity as resident chocolate guru, she researches other fermented foods and beverages like beer, sausage, and natto. Caitlin was drawn to fermented foods while living in rural Spain for six years, where she was exposed to traditional, time-honored practices of food preservation. At home, she practices Bollywood dance for fun and is followed everywhere by two small pet rabbits.

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