Willow Feeder

=== Ecological alternatives to human waste and and compost toilets. ===
==== Modern sewage treatment plants are problematic.  Liquids that enter the plant are typically released into our river systems within 24 hours and cause a lot of problems.  The solids are separated and usually hauled to a dump.   At the same time, there is a struggle to import nutrients for our horticultural practices.  Willow feeders, dry outhouses and greywater systems are designed to operate far better than a modern sewage treatment plant (which is better than a septic tank and drain field, which is better than an old school out house).   We will keep most of the valuable nutrients on the land, and we will have zero impact on our river systems and oceans. ====
To get a general understanding of the willow feeder idea, let's first take a quick look at alternatives.
A septic tank and drain field mixes all the feces and greywater together, then sends it into a tank.  Organic matter breaks down in time. The average septic tank is pumped every four years.  If you do a good job caring for what goes into the septic tank, you can go decades.  
The watery layer is a sort of fecal mixture that goes to the drainfield which is placed about 18 inches below the ground level.  There is a lot of bacterial activity that eats up the fecal matter all year long.  It does a competent job.  But some of the fecal matter makes it to the ground water supply.   Which is why when there is enough population density, it is time to get everybody switched over to a sewage treatment plant.
Everything is sort of stirred up into a slurry, and then screened - this separates the garbage from the sewage.  Garbage like flushable wipes, some toilet paper, feminine hygiene products, plastics, etc. Garbage goes to the landfill.  The remaining slurry goes to settling ponds.   After 24 hours, the fecal mixture goes past a UV light and is released into the river.
A good solution requires an understanding of pathogens.  For a few ailments, a person's feces can have bacterial and viral matter that can make other people sick.  This is called a pathogen.  If 4% of all people excrete pathogens, then we need solutions that will ensure that that number does not grow.  For the sake of creating a good solution, let’s assume that a sick person is pooping in every system.
There are some alternatives out there called composting toilets.  Some of those styles actually compost.   So you get a whole bunch of feces, toilet paper and sawdust together in a pile.  The pile gets hot in the middle due to the composting process - often exceeding 140 degrees which makes that part of the pile sterile!  The stuff on the outside sides of the pile didn't get hot enough and still contain pathogens.  Advocates for this technique encourage turning the pile frequently in an insulated container so everything (hopefully) gets hot enough at some point.  
When done well, the final product is a high quality compost that smells like good soil and is gardener's gold.  
I have seen some efforts at this that involve an open pile outdoors.   During the composting process, can a fly land on the pile, touch a pathogen, and then fly over to somebody's food and make them sick?   And if it rains, are fresh pathogens driven down into the groundwater?  Further, most piles either not turned, or turned only once - making most of the contents never having reached a hot enough temperature.  
But here is another angle about composting in general that has *gardeners* divided.  
When you compost, you might put in 100 pounds of compostable materials.   To make excellent compost you turn it several times.   When it is done, you have about 10 pounds of magnificent compost.  Where did the rest of it go?  Nearly all of what is now missing is water, carbon and nitrogen.   The water went into the ground or into the atmosphere.  The carbon and nitrogen went into the atmosphere.  But the carbon and the nitrogen are the very things we desperately want in our soils.
What is needed is a solution that is safer when it comes to pathogens, and brings more carbon and nitrogen to organic gardens.  
An interesting thing about pathogens ...  99% of them die in about two months.  That number goes up to 99.999% in six months.  And 99.9999999999% in two years.  Faster in a dry environment.  
As it turns out, a dry environment also stops the composting action.
What is also needed is to dry it out and set it aside for two years - just to be certain it is safe.   We also want to keep it from getting onto the ground too early and keep flies out of it.  
So we put it in a garbage can with a lid.  The lid fits well enough that flies cannot get in, but air can move in and out.   As each day warms up, the air inside expands so the moist gasses are pushed out.  And as it cools at night, dry air is drawn in.
We put a piece of breather pipe in the side of the can.  Then fill will four inches of sawdust.  And add three more inches of sawdust to the nearly full can.  Any moisture that gets to the bottom of the can is exposed to the open air through the breather pipe and can evaporate.
After two years, we have rich, pathogen free fertilizer.  It would be completely safe to put on a veggie garden.  Or to spread out on any garden element.  But just to make sure that nobody gets weird about human poop and food, let's stick to using it on something non-food.  
As the years pass, we find we want to empty the cans quickly and move on. Most plant species cannot handle this much nutrient at once.  But there are a few that can.  Willow, cottonwood, poplar and bamboo. They will greedily gobble up as much as we can give them and then lick their plate clean.
This material is not a waste, but a valuable resource.  I call all of this "the willow feeder system." Safer than a sewage treatment plant.  Cheaper and scalable too. 
== External links ==
* What is a Willow Feeder article at Permies.com
* greywater and willow feeders at permies.com
* willow feeder at permies.com
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