The (Literal) Ins and Outs of Curbside Composting

fresh produce spread across a burlap background

Is curbside composting a license to waste food?

Written by Mary Katherine (MK) Glen

Materials accepted in organics bins (also known as green bins)

So before I get into this I just want to specify that I’m talking about collection systems for food waste, not for yard waste. Here in Palo Alto, California, the city has residents combine food waste and yard waste in one bin, so I didn’t want to confuse anybody with the terms “organics collection” or “organics bin.” Most curbside waste collection systems collect yard waste and food waste separately. So for the sake of the post, I’ll discuss food waste, not yard waste. 

Where do compostable plastics go?

A lot of curbside composting programs (probably most to be honest) don’t accept compostable plastics, with one main exception.

Anaerobic organic waste processing facilities have the capacity to handle a wider range of materials, but these facilities are more expensive to build and are not as common as aerobic facilities. Most composting facilities in Canada and the United States are aerobic.

Typically, regarding compostable plastics, aerobic facilities can handle compostable bin liners only since they’re thinner than other compostable plastics and break down faster. So when compostable plastic says “compostable in a commercial facility” that’s very misleading. Not all curbside composting programs can handle these materials.

Another note about compostable plastics: Please don’t put them in the recycling bin! Yes they have a chasing arrow encircling a 7. But the chasing arrow indicates the type of plastic resin—it doesn’t actually indicate that a product should be thrown in your recycling bin.

Compostable plastics, made of plant material, have a different chemical composition than regular plastic made from oil. When compostable plastics get mixed in with regular plastics, they contaminate the recycling process. It’s possible that if you have curbside composting in your area that you can put compostable plastics in your organics bin, but you need to double check with your city’s waste management department. Most likely, these materials need to go in your landfill container. Again, ask if you’re not sure.

I’ve said this before, but I think compostable plastics reinforce the disposability mindset that we need to try to move away from. Compostable plastics are really only helpful for diverting waste from landfill in cities like Palo Alto that use anaerobic composting and can actually manage these materials through composting. In most instances, compostable plastics end up in the landfill, where they take up just as much space as their regular plastic counterparts.

Environmental impact of curbside composting

Ideally, we would eat all the food we buy. When food does go to waste, composting in your backyard is a great way to manage that waste—along with inedible food scraps. But backyard composting isn’t very accessible to people who live in apartments. So curbside green bins are a great thing to implement in cities because they allow people without yards to divert wasted food and food scraps from landfills.

But curbside green bins aren’t without their environmental impacts. Sometimes trucks haul organic waste hours away from its point of generation. This isn’t the most sustainable thing in the world, which is why if you have the option, it’s better to do backyard composting.

The environmental impact also depends on what you throw out. If you use your green bin for inedible avocado peels and eggshells, that’s much different than if you buy a bag of oranges and throwing moldy oranges in the green bin because you overpurchased. Food scraps belong in green bins, but once-edible food really shouldn’t end up in the green bin, or the trash.

a handful of compost made from food scraps
Finished backyard compost

Financial impact of curbside composting

Organics collection systems are easier to set up in urban communities. In rural areas, smaller tax bases and extra fuel costs of transport due to longer distances between homes makes organics collection more difficult. I think encouraging more backyard composting in rural areas is a great idea, especially because home ownership is usually more common and people have ample space to compost. Unfortunately, it can be hard to get people over the ick factor. (Go here for more on composting.)

Do curbside green bin programs encourage people to throw out food?

From my personal experience, I would say yes. I’ve seen friends throw food into the compost bin and say things like “Oh it’s compost so it’s fine.” But I couldn’t find any hard evidence for this online. Researching the effects of green bins on people’s attitudes toward wasting food would require two municipalities to collaborate and do waste characterization studies with the same sample sizes and characteristics. This would be an expensive undertaking. I’ve spoken to waste management professionals who say they would love to do more waste audits, but that cost is the biggest factor in why waste auditing isn’t more common. Which takes me to my next point, waste auditing.

What is waste auditing?

Basically waste auditing sorts waste into categories and weighs each category in order to determine the percentage of each type of waste in your waste stream. So if you audited a recycling bin, you would separate it into paper, glass, aluminum, cardboard, and so on. You would also remove things that don’t belong in the recycling bin (diapers, for example) and weigh those as well to calculate the percentage of contamination in the bin. High contamination rates indicate the need for more public outreach.

For a personal waste audit, you collect your waste and sort it out and weigh it. This can help you pinpoint problem areas where you have an opportunity to reduce your waste. For example, you may find that you throw out more food than you expected, or you may find you throw out lots of napkins or tissues.

From MK’s mom, Anne-Marie

fresh produce spread across a burlap background
Too good to waste

MK has explained here—like in her post on recycling—why prevention is the best solution to waste. But food waste happens. The following simple tips will help you reduce it:

  1. Shop the refrigerator, freezer and cabinets before you buy more food. In other words, eat what you have on hand before buying more food.
  2. Come up with a simple meal plan for from a couple of days to a week—or longer.
  3. Cook simple, highly adaptable dishes that you can add various ingredients to, such as soup, stir fry, frittata or quiche, grain bowls, fruit crumbles, hand pies and so on.
  4. If you have more food on your hands than you can eat, freeze some of it.
  5. Be prepared for the next time you find yourself with extra food that you can’t eat. Give it away on a food sharing app like OLIO. Go here for a list of other food recovery apps.

Go here for more simple ways to prevent food waste. And pre-order my book, The Zero-Waste Chef, for more use-it-up recipes and tips!

Mary Katherine Glen graduated from the University of Guelph with a degree in Environmental Governance and has a post-graduate certificate in waste management from Fleming College.

2 Replies to “The (Literal) Ins and Outs of Curbside Composting”

  1. lifeofanearthmuffin says: Reply

    Such a great post! One of the first things I did this summer when moving to a new city was to sign up for a service where they pick up my compost. I have been amazed at how much food waste I create, so it is nice to know that it is getting turned into soil (that then supports local community gardens). 🙂
    Jenna ♥
    Stay in touch? Life of an Earth Muffin

  2. The state of Vermont was the first state to institute mandatory food scrap composting last year. Our recycling centers have bins to collect the food waste and it is picked up by farmers who compost it and either use it or sell it. When you look at the state’s informational page,, it is heartening that the first line you see is “Eat what you buy, compost the scraps.” It seems to be working well but there are those things we can’t compost even though they are labeled “biodegradable or compostable” such as the little produce bags. They don’t break down and they don’t seem to work in our system.

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