How to Worm Compost Human Waste

by Max
(Columbus, OH)

Hello,

I am a student member Ohio State University's student chapter of Engineer's Without Borders. This past March we traveled to San Pedro Puxtla, El Salvador to construct three above ground latrines for an impoverished community.

Since there is not a real effective sanitation system for the removal of the feces when the latrines fill up, we are pursuing composting as a way to get rid of the waste. The town is located right next to a small river so the water table is extremely high, especially during the rainy season. This was the main reason that we built above ground latrines. When it is not in the rainy season the climate is dry and hot (usually in the upper 80's). Our goal is the construct one for each household in the community (approximately 29) and teach them how to clean them out when they fill, to compost the waste, and potentially sell the fertilizer to farmers in the area.

Our project team of about 20 students has been doing extensive research over the past few weeks on what the safest and most effective removal process would be and I have become very interested in composting through use of worms.

The 3 latrines already built separate the urine and we told the users to start adding leaves and other organic material after each use.

Here are my main questions:
1.) How long does the waste need to sit in the latrine, before it can be removed and the worms can be added? The expected fill rate of the latrine is about 1 year.
2.) Is there a very specific type of worm that we need to use? We would prefer not to buy worms in the U.S. and bring them to El Salvador. We hope to be able to find them somewhere inside their country.
3.) What's the largest size worm composting bin we can use and how long does it need to sit before it can be removed and used as fertilizer?
4.) What are the potential hazards associated with worm composting of human waste?

Answer from Big Tex Worms:
What an exciting project. Unfortunately, I have very limited knowledge about composting human waste. But I have an excellent resource for you.
I suggest you contact Joseph Jenkins, he is the author of the Humanure Handbook and should be able to answer all your questions. His web address is http://www.humanurehandbook.com/
I hope this helps.
Liz
BigTex Worms