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Micro Farms Project Email Record

Peggy┤s email about not using human wastewater for food.

Dear Todd and all,

I have on the website now a page on the Sierra. There is a map and the biggest town is Zoquitlan. The page is at the bottom of our microfarms page.

About a few issues.

Human wastes from house.

My instincts are to take the 1 cubic meter of water used by the family and sand filter it, then use it in flower beds around the house. If the house area is 200m2 then the 400m2 devoted to house space, 100m2 can be used to get rid of the 1 cubic meter of water, 10 liters per square meter. It should have nutrients added and the soap should be compatible.

The non edible flowers have a comfort value but also often have a higher market value than vegetables. Our Matzamitla project is raising lillies for sale in Guad as an example. Also the flowers represents a diversified crop. And it will use the nitrogen consumed by family.

Also the composting toilet ideally will conserve 4 kilograms of nitrogen per family member per year that can produce 400 pounds of crop. Flowers can also be dried and used for other salable products. I also favor any crops around the house that are not eaten including vegetable dyes, fibers, bamboo, even wood trees or firewood. A usable landscape could cool the home, make it beautiful and increase crop value.

I have asked Matt to look at designing this system for the home which can be used in any home to dispose of wastes. Right now in Mexico the waste water is thrown into the yard where it now is bare from the overload. This has great value outside of microfarm and would be a valuable paper or topic for postdoc.

Right now a ban on human waste for food for two reasons, 1. Potential for disease

2. Negative reaction of Latin American market. This is from experience and advice to me from Cesar Marulanda.

I also want the composting toilet to be hydroponic in that plant roots reach in and use the material so no one has to clean the toilet. It reduces some contamination. Further we need to get the family to wash their hands after going to the toilet as a habit which may need a bit more water per day. This has to do with fresh vegetable contamination as well as human health.

Matt would have an example Tilapia water to use for the crops, but the real issues are the ones you are raising about filtering, contamination, safety etc. Alberto has agreed to design the fish pond. However, he is a full time professor at Guadalahara I think.

About the ducks. I did several experiments for Japan in using chicken manure for hydrˇponics. We finally decided to compost first to get rid of some problems. One hatch of white worms from live chicken manure used with organic media did the trick.

But one of my partners in the work was Dr. Matsu Matsumoto, a chicken vet at Oregon State University. He was a little boy in Japan during the war and he got very sick because they used the human waste on vegetables "before it was ready". I did not ask him what illness but his beliefs have rubbed off on me. I see fresh waste as full of diseases. When it goes through a worm farm it is more productive I think. That is it is purified to some extent, and partly turned into live worm flesh with high protein value. We can do a mass balance on this.

I could not obtain data on what all a worm gut can get rid of but it is substantial.


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