Myth: Putting Food Waste Down the Disposal Is Greener Than in the Trash
Trash Talk: Are Sink Garbage Disposals Good for the Environment?
OMG hold your nose! There’s a mystery substance at the back of the fridge, and it’s scaring all the other food with its excessive stink. Now what? Pitching the moldy glob straight into the garbage disposal in the sink means it can basically disappear from your life instantly, i.e., not exponentially increase the gross factor in your trashcan days before garbage pickup. But that’s not the only thing in-sink garbage disposals have going for ’em. On top of the sheer convenience of it all, the rumors are true—garbage disposals are generally a greener option than trashcans.
Let’s get into the nitty gritty of this garbage disposal vs trash can comparison…
Garbage disposals, which have been heralded as the “next great tool for urban sustainability,” not only reduce the amount of diesel fuel and emissions associated with driving garbage trucks around town—but also carry this uneaten waste along to the wastewater treatment plant, where it can actually be used to produce resources like fertilizer and clean energy.
But let’s not get ahead of ourselves here. Though garbage disposals do have some clear benefits over trashcans, they are not the greenest way to dispose of your uneaten food, according to life cycle analysis expert Eric Masanet, PhD, of Northwestern University, and Debra Shore, commissioner of the Metropolitan Water Reclamation District of Greater Chicago.
What’s Greener than a Garbage Disposal?
Based on a variety of research and their own professional experience, both Masanet and Shore agree that the hierarchy of green ways to dispose of food goes like this, from least green to most:
- Not-so-green: Throwing it in a trashcan headed for the landfill
- Light green: Running it through the garbage disposal, from which it then heads to the wastewater treatment plant
- Green: Toss it in your compost bin for efficient composting
- Greenest ever: Reduce the amount of food we waste in the first place! Globally we waste about a third of our food every year. Talk about an environmental footprint.
Need more convincing on the garbage disposal vs. trash front? Here’s a brief DL on food waste disposals.
Getting Down and Dirty With Disposal Science
In determining whether one thing is greener than another, Masanet reminds us that it’s not just energy and water usage or greenhouse gas emissions we must consider, but all of them together and more. So, as we embark on this mini garbage disposal life cycle analysis, we’ll do our best to keep it fun (but, in all honesty, it may not be as entertaining as these laugh-out-loud ridic cat GIFs—you’re welcome). Let’s dig a little deeper in this garbage disposal vs trash investigation.
So, what exactly is green about garbage disposals? Plenty. At the most basic level, they simply help lighten the load for emissions-spewing garbage trucks. The most intriguing of their eco-perks, however, is that disposals have some major hidden value.
Most wastewater facilities skim out food scraps and return these nutrient-rich biosolids to soil as fertilizer for agriculture production and public parks—like the much buzzed-about Maggie Daley Park in Chicago.
(Hidden) Benefits of Garbage Disposals
Moreover, as Shore explains, when we send food scraps down the sink via our garbage disposals and to wastewater treatment plants like the ones in Cook County, Ill., it is broken down by bacteria in a process called anaerobic digestion, which allows us to capture the methane generated by decomposition of organic matter. Sorta like in this simple (we wish!) flow chart from the EPA…
So—rather than those greenhouse gases (GHGs) being released into the already overtaxed atmosphere, they are instead converted to electricity or biofuel, aka, clean energy. This is a big deal, considering that a Journal of Cleaner Production article found that the global waste sector is responsible for 3 percent of greenhouse gases.
Meanwhile, in landfills, the same decomposition is occurring, but on a larger scale and generally without as efficient a system for energy recovery. “Sending food waste to a landfill isn’t all bad if the landfill has methane recovery, which is a growing trend,” explains Masanet. For example, he mentions that Apple uses landfill gas to power some of its data centers. But landfill gas recovery is simply not as efficient as recovering gas from food scraps in wastewater, because wastewater treatment systems are working with much more concentrated food waste than landfills.
Sound like a pipe dream to turn ground-up food waste into clean energy? Shore assures us it’s not, directing our attention to the East Bay Municipal Utility District in Oakland, Calif., which seven years ago became the first wastewater treatment plant in the nation to convert post-consumer food scraps to energy via anaerobic digestion. And, she adds, Chicago’s Metropolitan Water Reclamation District now captures and uses between 50-80 percent of the methane generated at its treatment plants, a very attractive alternative to releasing those greenhouse gases.
Even if you don’t live in Chicago or Oakland, anaerobic digester systems are becoming more common in bigger cities. The EPA is all over this potential, and estimates that if just half of the food waste generated each year in the U.S. were to go through a anaerobic digester process to collect the methane from it, we would generate enough electricity to power over 2.5 million homes for a year.
Ah, But Garbage Disposals Aren’t Without Downsides
But wait! Garbage disposals are not without their impact, too, from the water and electricity needed to grind food scraps down the pipes, to the material needed to build these contraptions. Garbage disposals may also slightly contribute to nutrient overload in waterways—which, as everyone around Lake Erie recently learned the hard way, can pollute the heck out of our drinking water supply. This study in the Journal of Cleaner Production found that sink garbage disposals were responsible for about 2.1 percent of nutrient overload in the water—a much higher percentage than landfill trash and composting—but relatively quite minor compared with nonpoint source pollution, aka runoff from farms and fertilizer-spiked stormwater.
But…we still haven’t tackled the heart of the problem. “If you’ve got food waste, composting is typically best,” comments Masanet. “But even better is to not generate the food waste in the first place!
Leaving No Leftover Behind – An Even Better Solution than the Garbage Disposal or Trash
The real problem is not how we deal with trashed food, but that we waste so much in the first place. Globally, we waste about a third of our food supply, according to a report for the Food and Agriculture Organization of the United Nations. In the U.S. that number is closer to 40 percent of food, which represents more than a 50 percent increase in domestic food waste since 1974.
Yes, people are going hungry and we’re wasting money, energy, and water on food we don’t eat. According to this 2009 study, we’re using a quarter of our nation’s freshwater consumption and roughly 300 million barrels of oil per year to grow food no one ever eats.
How did we get to this point? Masanet thinks a lot of it has to do with our day-to-day shopping habits—we buy too much, don’t plan properly, get confused by sell-by dates, and often let what we’ve bought go bad. The good news is that there are some easy fixes for it.
EcoMyth Outcome: Garbage Disposal Vs Trash: Winner Confirmed, But…
Tossing food waste down the garbage disposal is generally greener than trashing it for a variety of reasons, one primary reason being that it more efficiently converts food waste into energy.
But, the sink disposal process still requires resources like water and energy to function, and can sometimes contribute to nutrient overload in our waterways. That’s why the greenest way to dispose of food waste is to compost—and the greenest thing to do overall is to reduce food waste in the first place.
Do One Green Thing
Reduce food waste by making a grocery list. (Yes, there’s an app for that!) or just use Google Keep (where you can readily share shopping lists amongst family members. (This works so much better than random bits of paper – your family can actually update it in real-time while you’re at the grocery store!)
Also…Reduce your own food waste:
- Plan your weekly meals before shopping, and don’t buy more than you need for each menu item
- Learn the difference between best-by, use-by, and sell-by dates so you don’t inadvertently pitch food still worth eating
- Do not fear less-than-beautiful produce. As we’ve learned from the farmer’s market movement, sometimes organic is just less attractive. But it still tastes good!
- Eat your leftovers—and challenge yourself to use them creatively (which doesn’t mean to overeat – just have a “leftovers” meal.
And…compost if you can:
- If you’ve got yard space, follow Shore’s example and start composting already! Not sure how to do it? Check out these Composting 101 tips
- If you don’t have outdoor space, try an under-the-sink option like this. Shore points out that even if you can’t use it all yourself, you can always share it with a community garden
- More and more, waste disposal companies are offering a compost pickup service as well. It’s as simple as recycling!
Do You Need to Wash Your Recycling?
It’s time we had a little talk. Sometimes in life, we have dirty things we want to, ahem, recycle. This can mean we have to rinse containers before recycling them…except for when we don’t. Well, it’s certainly clearer than it used to be. But, the need to rinse really depends on the local recycling provider in your area. More often than not, though, a light rinsing is called for.
It used to be that some cities, such as Chicago, didn’t need residents to rinse their recyclables. The services took on the job of cleaning recyclable materials themselves. But Chicago and more areas like it now ask residents to remove the bulk of food residue.
This change is likely due to the potential contamination of paper, now that many recyclers have moved to curbside “single stream” recycling – where glass, plastic, paper and cardboard no longer need to be sorted into separate bins at home.
Another benefit of rinsing is that good washing helps deter rats and insects from trying to get at the recyclables before pick-up.
Even within facilities operated by the same waste management company, rules vary by location. That’s because the washing, sorting, and recycling equipment is continually being upgraded, improving its ability to handle more types of containers.
How Clean Do Those Containers Need to Be?
But it’s not that complicated. Waste Management, Inc. the largest recycling company in the world, says this about rinsing recyclable containers:
While all bottles, cans, and containers should be clean, dry, and free of most food waste before you place them in your recycling container, they don’t need to be spotless. The goal is to make sure they are clean enough to avoid contaminating other materials, like paper. Try using a spatula to scrape cans and jars, or using a small amount of water, shake the container to remove most residue.
Republic Services, Inc., another of the largest recyclers in the U.S., provides some simple recycling rinsing guidelines, and very easy to understand reasons for the rinse:
“Recyclables must be empty, clean and dry to prevent the contamination of other recyclables in the collection truck and at the recycling processing center.
One ketchup bottle or not quite empty milk carton can cause your entire bin of otherwise perfectly recyclable items to be contaminated. Why? Because if the milk or ketchup leaks onto any paper, the paper is no longer recyclable. In some cases, the load won’t be accepted at many commercial processors. So, yes, it may end up in the trash.
“Unfortunately, contaminated materials have to be sent to the landfill, making your recycling efforts null and void.” But it’s easy to prevent this from happening by following these three steps:
Rinsing Recyclable Containers – Three Easy Steps
Step #1 – Empty.
First, empty all liquid and residue from food and beverage containers. This makes a big difference for the next step.
Step #2 – Clean.
Once excess liquids or solids are removed, give the containers a quick rinse – if needed – to clear any remaining residue. A rinse is usually needed for packaging that held milk, juice, sauces and condiments. A thorough wash isn’t called for, even here. No dish soap is necessary – a quick rinse and swish will do!
Step #3 – Dry.
Now that your recyclables are empty and clean – let them dry out. They can sit upside down in the sink for a bit. Just don’t put wet containers in the bin.
And don’t stress if a little water remains. The rule of thumb is to never leave more than a teaspoon of liquid in a container. This will usually evaporate before your recyclables get picked up.
Fortunately the answer in other areas is just a click away, thanks to Earth911’s recycling database, also available by app, which has compiled nationwide guidelines by zip code. Just enter the container type you want to recycle, and your ZIP code, and the search will identify the recycling facilities available for you. Then, check out the recycler’s guidelines.
As you’ll note, these recycling guidelines almost always say, “Please empty and rinse all containers and do not flatten containers.”
Why Aren’t Rinsing Requirements Consistent?
Why do the service requirements differ at all? And what happens if you don’t follow your local guidelines? We posed those and other questions to Eric Masanet, PhD, a Northwestern University Energy and Resource Systems Analysis Laboratory professor and researcher, and editor-in-chief of science journal Resources, Conservation and Recycling. His short take: It’s smart to follow the rinsing guidelines in your area, but not necessary to stress if you sometimes forget.
What happens if you don’t rinse recycling?
One big FAQ from people whose recycling service recommends rinsing is what happens when you forget to do it. Will your jar/bottle/can/what-have-you end up in a landfill anyway?It’s a valid question given that Waste Management, which manages half the country’s curbside recycling programs, used to state on its website that one dirty item can contaminate thousands of pounds of collected plastics. These days, WM just advises, “While all bottles, cans and containers should be clean, dry and free of most food waste before you place them in your recycling container, they don’t need to be spotless. “
But, yes, as Republic Services’ website says, “One ketchup bottle or not quite empty milk carton can cause your entire bin of otherwise perfectly recyclable items to be contaminated.”
So, please go ahead and rinse out any remaining liquids, in particular.
But the fact that an item is contaminated doesn’t relegate it to landfill status, explains Masanet. The recycling facility will use a mix of people and machines to sort then purify or clean everything according to type. Metal is the least sensitive to contaminants, he says, while plastic is so easily contaminated that even residue from a label can alter its chemistry and affect the quality of the recycled material in the end—exactly why recycling facilities have robust cleaning processes in place.
The real issue here is contamination of paper products in the same recycling bin. So, it’s more important to remove liquids than solids, like peanut butter.
More Reasons to Rinse Recyclable materials
Another downside of dirty recyclables is that contaminated recycled material has less market value—which means the recycling service provider has less to spend on things like improving service and green technology. So even though the recycling police won’t arrest you for not rinsing, Masanet advises complying with local guidelines so that the system is most efficient.
Curious about how recycling works once it leaves your bin? Take this video tour of a single stream recycling facility in Philly, courtesy of Waste Management, the country’s largest recycling provider.
Is Rinsing Recyclables a Waste of Water?
Another concern people have is whether rinsing recyclables wastes too much water. Generally though, Masanet recommends recycling as an “environmental slam dunk,” for saving energy, resources, and pollution. Even when considering water use on your end and at the recycling center, recycling almost always leads to energy savings when we consider the water needed to produce virgin glass, steel, plastic, or aluminum.
To rinse at home, just scrape out the majority of any remaining food with a spatula, and rinse it. Better yet, after washing any dishes by hand, just quickly swoosh around your recycling in the dishwater you’ve already used. That’s good enough for bottles, cans, and jars heading for your recycling bin. That’ll also be enough to keep your recycling bin from getting too smelly. The recycling facility will provide any further rinsing.
And, you’re not wasting water in the process.
How Much Water Does Recycling Save?
Working with data from various sources, Masanet is able to draw some interesting conclusions.
- For steel and aluminum, it takes 3-10 times as much water to produce virgin metals as it does to recycle them. In other words, even extensive rinsing won’t reverse the water benefits of recycling. (Supporting intel comes from EERE and the Aluminum Association.)
- For glass, the water use of recycled glass is closer to that of producing standard glass, but still, we’re likely to save 1-2 pints of water for every glass pint bottle recycled.
Conclusion: Prudent rinsing should preserve the water benefits of recycling. (Info from a WRAP report.)
- For PET and HDPE plastics, they are thoroughly washed as part of the recycling process given that they are sensitive to contaminants. Different life cycle analyses and different recycling processes lead to different conclusions about how much water recycled plastics save, with a range of negligible water savings to more than 30 liters for recycling a one-liter bottle. Masanet’s verdict: prudent rinsing is not likely to negate the water savings of recycling plastics, but reckless rinsing might. (Via WRAP.)
- So rinsing is nearly always the better, green approach.
A huge point to keep in mind, reminds Masanet, is that saving water is only one of the many benefits of recycling. We also save energy, greenhouse gas emissions, and pollution to air and water. “So, even if we occasionally use more water than we should, the other environmental benefits really make recycling a slam dunk.”
Uncovering the Basic Rinsing Tips
To rinse or not to rinse may not always have a black and white answer (it usually is!), but here are a few general pointers, in those cases where rinsing is not strictly required:
- Empty is preferable:
- It’s greener to consume or at least trash the food/drink/cleaning product in containers before recycling them. In addition to attracting vermin and upping the ick factor in your bin for the brave personnel who have to handle it, excess debris in your recycling bin requires extra energy to clean and dispose.
- Rinsing for single-stream recycling:
- Combined bin peeps, (those with “single stream recycling” – which is becoming more and more the norm) it’s a good call to err on the side of rinsing, since paper and cardboard are especially sensitive to residue. If nothing else, though, it is important to dump all liquids out of containers to help keep the paper goods recyclable.
- Conserve water when you rinse:
- Scrape food out first with a wooden spoon or rubber spatula, then swish a little bit of water around in the container versus letting it sit under a running faucet. If you have several containers to rinse at once, just fill up a bowl and use the same water for the whole job.
EcoMyth Outcome: Myth Mostly True – You generally SHOULD rinse all recyclable containers
You really should rinse all containers prior to recycling, unless your local recycling provider says you don’t have to. Emptying containers and rinsing when it seems appropriate will help make the whole process more economical. The main thing is to find out best practices in your area and follow them as well as you can.
And, as always, if there’s a question, contact your local recycling facility by phone or visit their website. You’ll almost certainly learn something else interesting along the way.
Do One Green Thing
Type your zip code into Earth911’s curbside recycling guide for the simple do’s and don’ts in your area.
More ways to help:
- Empty all containers prior to recycling them, to help keep paper and cardboard nice and dry.
- Rinse conservatively–no need to go all Mr. Clean on that milk carton when a simple swish of water will do the trick.
- Reduce use in the first place, as suggested by Masanet. How? Opt for items in bulk where possible.
The Multiplier Effect
If more people recycle their beverage containers, we’ll redirect salvageable stuff from the landfill and save resources needed for new material production. Here are three cool cases in point from the EPA:
- Five 2-liter recycled PET bottles produce enough fiberfill to make a ski jacket.
- Recycling one soda can save enough energy to run a computer for three hours.
- The energy saved from recycling one glass bottle will operate a 100-watt light bulb for four hours.
One More Thing…
A couple of more very important tips on recycling:
- Great that you’re recycling! Next step – are you composting? Check out our guide to figuring out what’s compostable vs recycling.
- Interested in composting those paper plates? Find out which paper plates are actually compostable (or not!)
- Don’t put plastic bags in your recycling bin – ever. Bags are very likely to jam up the sorting equipment.
- For any other potentially recyclable materials than the usual plastic bottles, cans, jars, paper and cardboard, be sure to check out your recycler’s website (or app!) to make something is recyclable.