Worm Composting

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The neighborhood started charging more tax for garbage (yay!)
and the compost small plastic bins in the summer would sit for too long and generate tons of flies and other creatures...and smelled very bad (boo!).
This was great motivation to try some worm composting.

What is Vermicomposting?

The Biology and Chemistry

Vermicomposting is a process that involves chemical, physical, and biological transformations of solid organic materials (agricultural residues of plant and animal origin) through the use of worms and microorganisms (Garg and Gupta, 2009).

Worm Anatomy as it relates to Composting

Image from North Allegheny School District Earthworm Dissection Page

The Biology and Chemistry in a nutshell in this short video by PBS and American Chemical Society.

  • Esophagus : Calcium Carbonate secretion to remove excess calcium from the body, and neutralize acidic food
  • Gizzard : This is where the food is mashed physically by sand
  • Intestines : This is where enzymatic and microbial processing of the ingested foodstuff gets digested
    • mucus containing protein and polysaccharides
      • digestive enzymes such as amylase, cellulase, protease, lipase, chitinase and urease
    • organic and mineral matter
    • amino acids
    • It's not only worms - microbial symbionts (bacteria, protozoa and microfungi) - also responsible for some of the digestive enzymes)
  • Anus : This is where the processed worm castings (waste, i.e. poop) comes out. One man's waste is another one's gold!

Some more details here in the Worm Biology

Worm Reproduction

Worm reproduction is a wonderful thing - this will allow you to share the worms with other people.

For E. foetida reproduction, taken from Sierra worm compost

  • Produce 3.8 cocoon per adult per week.
  • Each cocoon contains between 8-20 eggs, but on average only 3.3 worms will actually hatch.
  • Hatching occurs in about 3 weeks.
  • 53-76 days to sexual maturity.
  • 85-149 days from egg to maturity.

This video shows the reproductive process - worms are SIMULTANEOUS hermaphrodites, and sexual intercourse between two worms using both male and female reproductive organs will give rise to worm eggs (video).


Which worms can we use?
There are different types of worms
Overall categorization:
Different worms.jpg
More detailed table:
Table of Worms.gif


Concept behind the Prototype

Worm composting can be done indoors in small apartments, as well as outdoors.
Some basics:

  • Compost vegetable matter, even coffee rinds! - except egg shells - BUT no meat, no starch in your compost
  • Good moisture
  • Not in direct sunlight
  • Good air circulation (turn it over)
  • Balance the worm diet and balance YOUR diet! (too much citrus, coffee rinds will acidify, etc.)

There is a lot online on how to start one (links below) - this one aimed for these features:

  • One person
  • Balcony location
  • No need to touch the worms

The design here assumes that the worms are smart enough to want to look for food i.e. that they are epigeics (the worms like surface soil), which will stay on the top of the composting bin.

Materials and Tools

  • Plastic garbage bin
  • Plastic receptacle
  • Plastic receiving tray
  • Metal chickenwire / mesh
  • Metal support rods
  • Cutter for plastic
  • Cutter for Wires
  • Drill (to make airholes)
  • A ziptie for a handle
  • Salad turners for "tossing the compost" for aeration


Can you dig up worms yourself in the garden and do this?
The answer is no, for this type of design. See above for the types of worms.
Otherwise, look for suppliers in the neighborhood.

Build it

Wormcompost start.jpeg

Choose a bin.
This one was chosen because it was lying around
but also because there was a pedal to open the lid -
no need to juggle the organic waste, and try to open the lid of the compost bin.

Wormcompost receptacle.jpeg

Take an old tupperware, something that fits into the compost bin.
Cut a window big enough so that the receptacle can easily be taken out.
Next time around though, the window should be higher off the ground to allow for some brown water to collect,
so that another tray is not necessary.

Wormcompost supportgrid.jpeg

Some height above the receptacle, 2 aluminum rods were inserted to support the chicken wire.
Surprisingly, this is sufficient - even though it is super holey, to support the compost.
Hardly any worms drop down, nor are there huge chunks of random things that fall down.
Here, you can also see the drill holes for aeration.

Wormcompost firstlayer.jpeg

For initial support, layer some cardboard.
Worms eat cardboard!

Wormcompost firstorganics.jpeg

Then layer some food.
People mix with dirt...

Wormcompost addpaper.jpeg

Or just some wet newspaper.

Wormcompost 3months.jpeg

No fruitflies no maggots, less garbage no odors and no trips to the local organic garbage bin.
The worm numbers are increasing.
The sound of them moving around at night is mesmerizing.

Wormcompost 2years.JPG

After 2 years and a move it is going strong!
The main issue is the brown water - ideas to improve the design, see below.

Repeat of What not to Compost

What not to compost at home:

  • Dairy products
  • Meats
  • Oils, fats
  • Pet waste (contains harmful pathogens - unless processed in heat compost)
  • Sugars (attracts ants)

In effect, a good vegetarian mix + also, coffee, tea, plants, paper (cellulose).
Rotten food is welcome.

Onions, garlic or citrus (in small quantities), not too spicy also.

Chop them up for easy eating.

Feed them, and see how it goes.

Troubleshooting and Improvements

Using composting worms (Eisenia foetida), there are hardly any worms try to escape from the bottom. There was never a need to "separate" the worms from the compost, which most articles suggested to do. But here are some things to do differently than this version.

  • Need a bigger bin!
  • Make the "bottom window" to take out the compost a bit higher off the ground, to catch the brown water, especially for indoor composting.



Other articles

Worm Science

Worm Sources



Nicely Designed Worm Compost Bins

  • wormup makes them in sustainable ceramic!