Question

I want to start a small kitchen compost bin for our plant waste. Any advice for an urban composter?

Asked by Lauren
Washington, DC

We live in a small apartment in the middle of the city with no balcony, so moving our compost to a larger outdoor bin is out of the question. I finally snagged a 3.5-liter ceramic compost bin with filter to hold the scraps... I'm just not sure what other steps need to take place. (If possible, I'd also like to avoid the use of any worms in my kitchen.)

Answer

Kirsten Flynn

Answered by Kirsten Flynn

Palo Alto, CA

Sustainable Home

October 12, 2010

Dear Lauren,
 
First of all, I totally sympathize with your desire to create less waste. It always bugged me to throw out things that were not strictly "trash." I realize that interior designers don't usually give advice about trash, but I have composted food waste for the last 20 years, largely motivated by my desire to create less garbage.

Indoor composting basics -- good news and bad news

The good news is that "rot happens," whether you do anything to help it along or not. So if you have a bin full of plant waste in your kitchen, it will begin to self-compost.
 
The bad news, and the reason that a lot of folks might develop the idea that composting is yucky, is that an unattended compost pail will start anaerobic digestion. That means it starts a process of rotting without the presence of air, and this process smells bad!
 
An urban composter wants aerobic digestion to happen, which means that the natural materials break down without odor. The reason that a backyard composter will turn or mix a compost heap is partly to introduce air for more efficient, odor-free composting.  
 

For compost that is good for the garden, it is also helpful to have a good mix of green material (fresh food waste would be in this category) and brown material, such as small twigs and dry leaves.

  • The greens tend to be moist and have more nitrogen; and
  • the brown materials are high-carbon materials that tend to be dry.

In an urban setting, shredded newspaper or purchased coir blocks can be your source of brown materials.

Think twice before you rule out a worm bin

Another way to introduce air is through the use of the miraculous little digesters: worms. They tunnel through any food waste (except meat and dairy) breaking it up, eating it, and keeping your pile aerated.
 
A worm bin is probably the most efficient, least expensive way to compost in a small area. They are easy to contain, and if the bin gets too wet you can throw in newspaper or coir. If your worms do not have any access to outside materials, it would be good to give them a small portion of Azomite or other rock dust. Worms are a bit like birds; they need some grinding materials in their gut to help them digest their food.

If the worms are not too damp, and have food waste in their bin, they will never try to join you in the rest of the kitchen. They will just work breaking down your food into high-quality fertilizer. But you did state that you were not a huge fan of having worms in your house at all, so let's move on!

Other composting options for a small indoor space

You are not the only person who has faced the challenge of composting in a limited space, and there are a couple of products designed to help compost in an apartment:
 
  • Nature Mill
  • Green Cycler
  • Bokashi

Nature Mill

There is an appliance called the Nature Mill, which grinds and warms your food waste to accelerate the breakdown into usable compost. It uses about 10 watts of power a month, which I would guess is a great deal less than the fuel that the trash truck burns to haul the food garbage away to the landfill!
 
I have lusted after this item for many years, but at around $300, it has not so far been in my budget.
 
It is the perfect solution, though, for someone who wants completed compost, but does not want a worm bin.

Green Cycler

For a more reasonable machine that will prepare your food waste to accelerate composting, you might take a look at a brand new product, the Green Cycler.
 
This product grinds your food waste so that it will break down quickly, and is targeted to sell at around $99. It deposits your ground scraps in a biodegradable bag which you can chuck into your composter of choice when it is full.
 
This might be a great option if there are any community gardens in your area. You could work out an arrangement to add your compostable bag full of food scraps to their pile, in exchange for some completed compost for your house plants.

Bokashi

To find out about other options for an apartment-dweller who does not like worms, I contacted Common Ground, a local garden supply and education center. They have wonderful classes on worm composting, and I wondered if they had heard of any other options.
 
  • Apparently there is a technique used in Japan called Bokashi, which uses fermentation to digest food scraps anaerobically.
  • One advantage of this technique is that you can add meat and cheese to the bin.
  • However, the disadvantages are that you cannot add scraps continuously, and that you must bury the material in soil to finish composting. (Obviously not an option if you have no access to a garden.) There is a very clear explanation of the process here.

Why compost?

It is interesting to see how different cultures are solving the same issues. Food waste is up to 50% of the garbage sent to landfills in urban areas. If you use a garbage disposal in your sink to grind organic food waste, this material is added to your civic water processing, putting an additional burden on that system. Also, food waste contains a great deal of usable nutrition that can enrich our soil. It seems a shame to toss it out.
 
As our urban areas are becoming more and more dense, more and more cities are encouraging food composting, like the City of Vancouver, which has a huge worm composting program. As time goes on, I am sure there will be many more solutions.
 
I hope that this has been helpful, and good luck with whatever solution you choose. Rot will happen; the only problem is making sure it happens without smell or mess.

 
For more information:

To learn more about creating a green kitchen in an urban home, read "New York Tested: Tips for Efficient Use of Kitchen Space."

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