Run-off: Compost vs. Garbage Disposal vs. Trash

by April Paffrath

"If it's broken, we'll just take it out and not replace it."

Those heart-stopping words were spoken by the building manager about our kitchen sink disposal, which quit working the other day. It's not like we use it for everything, but we use it a lot. Her reaction was a bit panic-inducing as I thought ahead to a summer full of cooking. I couldn't do without it, even though we try to compost as much as we can. I consider it an essential part of the kitchen because some food items go down the sink and I'd rather grind them up instead of getting a clogged sink from carrot peels that slip away. Plus some days you've cooked so much that you have more than fits in the compost bin.

Granted, our compost bin is small—it fits on the top shelf of the fridge. Even though it has a charcoal filter to reduce odors, we store it there because rotting food and mold give me a massive migraine. We live in an apartment building, so when it gets full, we drop off the contents at Whole Foods and the Cambridge Department of Public Works.

But the uncertain future of our In-Sink-Erator got me thinking. Does it make sense to grind up food and send it into the water system? What's the ranking of food waste between landfill, compost and water system? Slate had a great article for their Green Lantern section a while ago about disposals, but it didn't actually answer the question if you don't know how your region and town treat waste. So I got on the phone this afternoon and made some calls to find out once and for all.

This summer, as I core red peppers, trim celery ends and more, where will the waste go?

Landfill
Landfill is a serious problem. I think that's pretty much a known given. The main problem is that the piles of trash and organic matter just sit there. Oxygen doesn't touch most of the trash so it undergoes anaerobic decomposition. The byproduct of that is methane, a powerful greenhouse gas, much worse for the environment than CO₂. I put a call into the Cambridge Department of Public Works to see if they have any measures to trap and burn off the methane (and harness the energy, hopefully), but they haven't gotten back to me yet. I'll update as soon as I hear.

The City of Cambridge Climate Protection Plan publication about reducing greenhouse gas emissions says that the "2000 Solid Waste Master Plan prepared by the Massachusetts Department of Environmental Protection sets a goal of reducing municipal solid waste by 60% by 2010. Currently, Cambridge has achieved a recycling rate of 33%, so the City will essentially need to double its efforts with a combination of waste reduction, composting, and recycling. "

That means, like most of us are aware, the city wants to reduce the use of the landfills by reducing the trash input. Doing my part to "double the efforts" means that I need to put as little in the trash as I can, including toast corners and peaches that have gone moldy.

You know, it also means that I should think about things before I buy them and try to reduce packaging and waste through my purchase choices. Having a CSA takes care of some of that—non-processed food in no packaging. Bonus points on the health, taste, and environmental fronts.

Compost
Compost is sort of like a landfill, but it changes into amazing, nutrient-rich dirt. Compost gets turned and rotated, either by pitchfork or gravity. In college I even had a worm composter in my apartment (what can I say? It was Ithaca, NY.) which also breaks down and aerates the organic material. That physical action means the matter gets exposed to oxygen, which spells aerobic decomposition. The byproduct of that is CO₂, instead of the methane from the landfill. If you actually take care of your compost heap (or bin or pile), it will follow those decomposition rules. CO₂ is not nearly as bad as methane, so that's great. Plus, it adds so much to flower and veggie gardens.

Sink Garbage Disposal
The water that goes out our sink—whether with soap from washing, or with apple cores from the garbage disposal—is treated by the MWRA (Massachusetts Water Resources Authority) at Deer Island, by Logan airport. The sewage decomposes in the big white egg-shaped structures that you can see when you're coming in for a landing over the harbor. There, bacteria are breaking things down and the sewage is decomposing.

Like a landfill, the by-product is methane. However, 98 percent of the methane is captured and burned at the plant. The burning methane provides the heat and hot water for the facility. The MWRA also captures the steam and uses it to run the turbine generators that provide energy for the plant.

Once the sludge is fully digested, it travels through a tunnel to Quincy where it's processed into fertilizer. The liquid run-off is treated and sent through 9 1/2 miles of pipe far into the harbor. It's released through a diffuser over 1 1/2 miles long so it's not a concentrated release of nutrients (for every 1 gallon of pumped water, there are 70 gallons of sea water).

The MWRA focuses on green methods. The methane is used and the solid waste is used. The water is treated, de-chlorinated and diffused into the water system. The only things that go to the landfill are large non-organic items that weren't supposed to make it into the water system.

So, my cooking output and trash needs a home this summer.
Here's the final count:
Best option: Compost
Next best: Sink disposal
Not-so-good: Trash/Landfill

That's pretty close to the priority we had before. However, I feel a lot better about using the disposal than before. I was having some guilt about it when it's actually much better for Boston-area residents than I thought. If your town doesn't have methods to trap methane or treat the sewage properly, it might be different for you. And, as the Slate article points out, if you're in a low-water area, you don't want to tax the water treatment or use more water than you have to at the sink.

Wondering where to get your composting goods?
Whole Foods sells composting bins, as does Greenward in Cambridge. We picked up ours on a run into the Container Store...not my favorite shop, but they have good glass kitchen containers for storing food in the fridge. If you want a cool ceramic one, I found this cute honeypot-shaped one online.

My friend from BostonMamas.com uses this Envirocycle large rotating bin in her yard. If you're interested in indoor vermicomposting (composting with worms), check out my friend Holly's experiences.

If you don't have your own space for compost, you can drop your food scraps at Whole Foods. Call your location to make sure they'll let you. The Department of Public Works has drop-off days throughout the week.

Update: Right after posting, the super came over and hit the reset button on the garbage disposal. It works again! My gosh, I love reset buttons.

Photo courtesy of shygantic on Flickr

Comments

[Nancy]

Hi, just came over from 5 second rule to check out your blog. Interesting stuff--I was just wondering this about my own disposal...maybe I need to make some calls too.

[Conor MacDonald]

This post is so awesome and full of the kind of information that I would worry about forever and never actually discover on my own.

Thanks!

[Best Garbage Disposal]

Disposals are great for getting rid of scraps from plates, but avoid putting big, tough stuff down there. And say absolutely no to pasta, fats and grease in quantity, anything you wouldn't want to clog up your drain.