Sanitation video script (8m 42s)
Use it up, wear it out, make it do or do without.
-New England proverb
The principle of the sanitation chapter is how to produce no waste.
Waste is something that is not wanted. It’s a perspective. When we look at plastic bottles or poop for example, we may in a conventional sense, see these things as waste. But in permaculture, we’re bringing value to these things and essentially get rid of this perspective that some things have no meaning. Everything is useful.
There are two types of waste you’ll find in a typical residential setting – trash and poop. In this chapter, we’ll talk about how we can deal with commercial byproducts and our feces.
Common types of commercial byproducts are: plastic bottles, glass bottles, plastic wrappers, metal scraps.
So first the trash cycle, there are four parts to this cycle we’ll cover here:
First thing, if you have to think about buying something, you probably don’t need it.
For trash you do create, recycling bins are a good way to break down what you have: Splitting up your trash into metal, plastic, glass, paper and organic bins are a good way to cut down on the total volume of trash. And by splitting up these materials, it makes it easier to see the value in each of piece.
Trash compactors can reduce the volume of trash easily by 90%. Here’s an image of the Temple of Trash. This is a pyramid made completely of compacted garbage bales. Depending on the volume of the trash you have, you can build a domestic sized trash compactor to make small bricks or something larger like a trash baler.
Recycling centers like Goodwill are great places to take stuff that isn’t quite garbage, but just things you no longer have a use for. You can find some real gems in these kinds of places.
There’s an organisation in Auroville called Eco-Services. The collect all of the garbage produced by this city of the future and split up the trash into several bins. We’ve gone there a few times and found some real gems.
So that’s the generally the commercial side of residential waste, now we’ll talk about the more human side, our poo and pee.
What is in our feces and urine? Our poop and pee is made up of organic matter, nitrogen, phosphorus, carbon and calcium. Listed are the average percentages found in each substance, sourced from Natural Farming book by Dr Tancho from the Mae Jo University in Thailand.
Organic matter 88-97% 65-85%
Nitrogen 5-7% 15-19%
Phosphorus 3-5% 2.5-5%
Carbon 4.4-5.5% 11-17%
Calcium 4.5% 4.5-6%
The percentages here are less important than knowing these elements are there. The building blocks of plant nutrition and soil nutrition come from our feces and urine. And we can make these nutrients available for the soil by composting them.
Now we’ll talk about composting toilets and then about flush and bio-gas toilets.
The Humanure Handbook is a good book that explains human compost and just how powerful composting is. The author, Joseph Jenkins, wrote that you can actually compost dynamite. Dynamite can be broken down by compost… to demonstrate how powerful a simple poop composter can be.
There are many ways to make a dry composting toilet. One type of compost toilet is an Arborloo. It’s a hole in the ground with a floor or a chair or something to sit on, and lightweight walls for privacy. The hole is small, about .5-1m cubed… you poo in it until it fills up, then you move the walls, dig another hole, move the structure. Then you mix compost and dirt with the poop and plant a tree. Adding compost and dirt helps kill the pathogens. By the time all of the pathogens die off, the tree will be a sapling and can go from there.
The next type of toilet is a 5-gallon bucket. In Haiti, there is a group called www.oursoil.org. They are installing 5-gallon bucket systems in communities. They empty the bucket in a 3-tiered poo chamber. In the first chamber, they dump the poop, then mix compost and carbon to it, and then after a few months they move the poo to the next chamber, let it break down more and then finally put it in a third chamber when its ready for the garden.
So 5-gallon bucket toilets are an effective composting toilet. Just be prepared to move the poop every so often.
Another larger type of toilet is a composting toilet. This is the same thing we have been talking about, just a bigger hole. And instead of leaving the poop there permanently, or moving it regularly, a composting chamber is a structure that will hold the poo during the decomposition period and then, after that 6 month period, has a hole where you can break in, remove the poo and spread it over your compost pile, forest and even your garden.
When I was staying at the Panya project, several other people and I built this massive composting toilet. We decided to make four chambers, each chamber measured 2m x 2m x 3m, which is a total of 12m3 per chamber. Once we completed the toilet, an average of 20 people made daily deposits and after 9 months, the first two chambers still were only about half full. So in calculating the size of a poo chamber, I think we could have built chambers about 1.5m3, about 3.375m3, and saved some time and space.
A few modifications you could add to your composting toilet…
One is to add a solar collector to the outside. A solar box collects heat from the sun and channels this heat inside the chamber. This could speed up the composting process… and probably shorten the time needed to kill pathogens. There may be a chance of the chamber catching on fire. I’m not sure though.
You can also install a urine diverter. If everyone pees in the poo chamber it will smell. If only some people pee in it, it’s okay. To reduce the pee in the poo chamber, you can install a urinal for males, or at one project in Auroville, I saw they had a separate hole right next to the poo chamber so you just kind of shimmey forward and pee in the other hole.
A few notes on flush toilets. Conventional toilets can use anywhere from 2-5 gallons (or 8-20L) per flush. So first off, if you’re trying to conserve water when designing a flush toilet, using a manual flush, like a bucket or bum gun, as is commonly found in Asia… this is the most efficient means of disposing your poo.
When you flush a toilet, more than likely it’s going to go into a septic tank. Septic tanks are typically two chambered concrete basins. The first one receives the intake, allows the solids to settle, the scum to rise and then pour over into the next chamber. Then when the second chamber fills up, the run off exits the tank and runs into a drainfield. Septic tanks also need to have a manhole or some way to access the poop. Then when the tank filled up, you call the local honeywagon, a truck which comes by and sucks out all those valuable mineral deposits.
In more industrial sized waste-water treatment plants, they add chemicals like alum, chlorine and fluoride to the waste water to kill the pathogens and return the water to some state of cleanliness to be used again.
Interview with wastewater treatment people
Then from the septic tank, the water can be channeled into a drainfield. A drainfield is a series of corrugated PVC pipes running under a field. First dig trenches, then line the trenches with plastic, fill in a few centimeters with gravel, drop the PVC lines, cover it with gravel, and then add soil and plant your garden on top. I’ve talked to people who discourage growing edible crops on top of a drainfield, then I’ve also seen pictures online of gardens titled blackwater drainfield garden. I think plants naturally provide a filter for pathogens as they grow food. But I can’t say for sure. If in doubt, just plant trees.
In Auroville, groups are researching some really amazing ways to treat grey and blackwater using natural methods, dynamised water and water vortecies.
A side note on toilets
In Dominican Republic a few years ago, I was working with a small Haitian community. After doing a community assessment, we all decided toilets were one of the main things to try and build.
Last thing I’ll talk about is bio-gas. Bio-gas is an efficient way to transform human waste into cooking fuel and a high-nitrogen compost additive called bio-slurry. It’s where poop and food waste turn into fuel, which can be used to cook more food from which we’ll make more poop. It demonstrates a beautiful symbiosis in how we dispose of our food and how we prepare our food.
All bio-gas systems have a similar design regardless of what you’re composting. To make a bio-gas toilet, you channel the poop from the flush toilet into a separate closed chamber creating an anaerobic environment. This chamber is designed to extract methane from solids.
First add cow manure. Cow manure helps to get the fermentation going. The solids break down, the methane from the poop rises, and pushes up another chamber floating on top of the base chamber. Remember the whole system is filled with water, Bio-gas is a water tight container of fermenting poo. Once the methane is extracted, it can be used for cooking fuel.
As you continue to make deposits, the poop is pushed out another pipe. This pipe is channeled to a slurry pit. The slurry pit needs to be lower than the toilet and lower than the floating tank, the methane extractor.
Bio-gas slurry is a super high-nitrogen substance that is very useful for the garden, compost, forest, etc. At Saelao Project in Laos, the slurry pit sits in a fairly open space and it doesn’t smell. So I take that as a good indication that bio-slurry isn’t pathogenic. Nonetheless, I would use caution if you want to put it directly on your garden.
So from here on your site designs, consider how you can reduce, recycle, contain and compact the trash you bring into your home. And, let’s consider how we poop and where it goes after we poop. And this way, we can turn our garbage into gold.