Mill Is Turning Your Food Waste Into More Food

Throwing away food is a problem (how many burger buns and leftover watermelon cubes did you throw out over Memorial Day weekend?).

As soon as that trash hits your waste bin, the decomposition process begins, off-gassing smelly compounds into your kitchen, and prompting you to dump out the trash. But just because it's out of your house doesn't end the impact of that half-eaten Chipotle bowl. Wrapped in plastic, each bag of trash gathers metric tons of greenhouse gasses like methane and belches them into the atmosphere every year.

While some companies, are tackling the household food waste issue with countertop appliances that turn your trash into, well, drier, less smelly trash that can be mixed in with your gardening, one company is doing more.

Mill Kitchen Bin with scraps awaiting processing

Rather than spreading that food waste around your yard (which can cause mold and mildew issues when it gets rehydrated by outdoor moisture), Mill is taking your leftover burritos, onion skins, and boxes of stale crackers and using it as raw material for chicken feed.

That's right, the food you eat becomes food for the food you eat.

Life is crazy sometimes, huh?

Before and after a cycle

Mill is a service focused around a trash can-sized kitchen bin that agitates and dehydrates food waste. Why dehydrate? Water is the main culprit in that funky smell you're punched in the nose with every time you open your trash can. Not only does it allow bacterial growth, it takes up space. Much like us, the food we eat is largely composed of water. Get rid of the water and you not only rob microbes of a free lunch, you reduce the volume significantly.

The resultant powder is dumped into a prepaid box with a plastic liner that you send back to Mill. They process your food waste and turn it into chicken feed, which they then sell to interested farmers (having just launched, they're still working on those partnerships). It's a closed loop system that works off the premise that your food "waste" is still a useful product. Which, if you really think about it, makes sense. People have been using food waste as compost for gardens since humans started putting seeds in the ground. There are still valuable nutrients in your leftovers…even if you can't use them.

There's an app as well that you can use to control your bin, check for cycle updates, request box pickup, check your personal impact based on previous shipments, and explore Mill's extensive article library.

Mill has done their homework. Since their service is brand new, they don't yet have actual user data to crunch. So they've conducted a Scoping life-cycle assessment (LCA) that factors in everything from manufacturing of their hardware to the impact of the production and transport of grain for chicken feed that they're proposing to replace. All things considered (quite literally), the numbers favor Mill's approach to the tune of approximately half a ton of reduced greenhouse gasses per year per household.

Cat for scale

You'll see immediate impacts in your home environment as well. Since the Mill bin is quite large, you can load it up like a regular trash can. So, unlike with countertop composters, you don't have to do phased fridge and pantry cleanouts. And processing rather than throwing away food scraps leads to less volume and stink in your regular trash, meaning that you throw out less plastic bags for landfills.

And as far as reducing your impact when you ship back the food waste (which you aren't obligated to do, you can add it to your compost heap if you're so inclined), Mill has partnered with USPS, who pick up the Food Grounds with your regular mail delivery. Granted, those trucks aren't the most efficient…but that's a whole different story (and hopefully, someday soon, USPS EVs will be a thing).

The crucial bit of the puzzle will be Mill getting enough subscribers and processing enough food waste that they can produce chicken feed at a sufficient volume for the farmers they partner with. Once they start operating at scale, the long term environmental benefit clearly favors their model.

Boxes to ship your Food Grounds are included in your Mill subscription

You open the lid, you dump in your food. At 10 PM each evening (you can adjust this in the app) Mill starts a cycle and processes your food waste into Food Grounds. By the next morning (or maybe mid-morning if it has a lot to process) Mill is ready to start the cycle again. Repeat until the green blinking light shows up on the lid, indicating that the bin is full. Then you dump the Food Grounds into a provided shipping container, seal it up, and place it to the side. Repeat until the box is full and ship it out.

It's a process with a lot of steps but no single step is especially hard. Mill is simple enough to use that even your family members who grumble about new gadgets showing up all the time will accept "OK, throw food away here."

I appreciate that you can either open the Mill bin with a pedal if your hands are full (just don't take your foot off until you're done, the lid closes fast) or you can manually open the lid to keep it open. When working through a cycle, the lid locks, but you can interrupt the cycle with a button press or via the app to add more food scraps.

While operating, Mill is extremely quiet, probably quieter than your dishwasher. There's the occasional clunk if you've dropped something large or hard into the bin. Odor-wise, I've been operating my bin for weeks with no discernable smell at all. The refillable charcoal filter does an excellent job of keeping smells from processing your food waste in the bin. If you have a bin that's close to being full, you'll get some odor when you toss new food waste in. You'll definitely get a whiff when you dump the Food Grounds into a box for shipping (you might want to do this outside). Otherwise, Mill does its job quite agreeably.

To think this was all food 10-12 hours ago

So what can you put in Mill? Pretty much anything that you put in you…plus small bones (like chicken…which brings up a whole cannibal chicken thing that I fear may unleash the zombie apocalypse, but I digress), eggshells (see the previous aside), and any scraps you have leftover from making dinner like rinds, seeds, and pits. What can't go in? Compostable cutlery, cooking oil, and large amounts of processed sugar (sorry, you'll have to find somewhere else for that half-eaten birthday cake to go). You also can't toss in your unused prescription drugs…but you shouldn't just be throwing that stuff away anyway. Take it back to the pharmacist. If you have any doubts, consult the app.

Mill App

The app is extremely well designed. Operationally, it doesn't do a ton but it doesn't need to. You can start the bin, check to see how long your cycle has left, and schedule pickup of your Food Grounds. But if you want to really dive deep about Mill and their process, it's a fantastic resource. Their in-app article library is one of the easiest to use and most informative that I've ever encountered for a consumer product. The content is extremely informative and engaging (as someone who writes technical documentation for a living, I can tell you that's not an easy task to pull off). One of the most helpful elements of the app is that you can enter a type of food and instantly find out how Food Grounds compatible it is.

Between the ease of operation and excellent app experience, Mill is a pleasure to use.

You can't buy Mill.

All of this convenience and efficiency comes with a subscription fee. You can either pay $396 for an annual subscription or $45 per month with a one-time $75 bin delivery fee. For that you get the Mill kitchen bin, all the Food Grounds boxes you need, and automatic replacement charcoal for your filter, plus dedicated member support.

If you're paying for green bin service with your local municipal waste handler, switching to Mill makes sense. It's a better solution than whatever your local garbage person has (be it incineration or…just dumping it into a separate landfill). But green bins haven't really started being a thing in the U.S. yet. So why pay for a subscription?

Mill is creating a closed-loop system unlike any other and working to unlock the potential of the food you throw away. That requires regular infusions of capital. The model is unsustainable when based on a one-time hardware purchase.

Yes, you can buy a smaller countertop appliance and just throw away the "soil" or "pre-compost" (or whatever term the company has coined for "dehydrated, ground-up food waste"). While that has a small impact on your carbon impact (mostly by reducing the amount of trash you generate), Mill gives you the opportunity to actually have a greater individual impact by generating something useful from your Food Grounds. I hear time after time how individual actions have little impact on the environment. But when it comes to garbage, all of us being more mindful of how we treat what we throw away can have a massive effect.

Mill is in the early days of rolling out their subscription service. Head to their website where you can sign up to reserve a kitchen bin in the next batch and learn more about the company.