Sewage at 7L- closing the human food cycle

Eva gave us a tour of the compost toilet system at 7L. She said that a toilet without a disadvantage has not yet been designed.

7L have four different types of compost toilet and each one has advantages and disadvantages.

These are some photos of the first type of compost  toilet she showed us, which are the ones we used in the building for the public where they hold courses. They are lovely and easy to use. P1320612 P1320613 P1320615     P1320617There is a pee separator and when you have done a ‘big job’, as 7L calls it, then you need to pull a handle to allow sawdust to cover what you have done, keeping the smell away and helping with composting. But as a user you don’t see, hear or smell anything. P1320616They are slightly more prone to getting dirty than a flush toilet. However the real drawback is that you need to design a room directly beneath them as gravity is used. This room also has an electric exhaust to keep smells away. The bins are emptied every two weeks. Here is the room with the barrels that collect the waste and the sawdust mechanism directly below the toilets:

P1320627 P1320631P1320636       P1320629The second type of compost toilet has the same set up at the user’s end as the first type, with pee separator. Again you don’t see, hear or smell anything. This toilet has a huge waste collector and compost bin together. It needs lots of space to store it. It needs emptying only twice a year and should contain composted material when emptied. But Eva said it hasn’t worked. So in fact you have a horrible sludge that comes out of it. Here is the collector:P1320638The third type of toilet is a plastic style one that looks like a chemical camping toilet. Here you can see everything although there is little smell. You do not need extra space to store it. Emptying it is easy, as a bucket pulls out. Again urine is separated. But this toilet is not accessible for everyone and some people object to looking at what has been done before them.

P1320648 P1320647The fourth type of toilet is a wooden shed in the grounds, much like you would find at a festival with steps leading up to it. It was a wooden seat and everything goes into wheel barrows underneath the structure that are wheeled away when full. Here you can stand or squat to go.

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Where does it all go?

Urine is sent into the grey water and the reed beds.

Some of the faeces was put into a pile with lots of straw. This has not been used at all.


Now they have built bins, behind a lovely wooden gated entrance, where the faeces are mixed with green waste (garden and veg matter) and brown waste (straw and leaves) to hot compost it. Composted ‘big jobs’ cannot be used on the fields at 7L as they use their food commercially i.e. they feed it to their paying guests such as me.

P1320680P1320679  P1320673 After one set of composting (first photo below) it is layered with straw and composted more (second photo below). Eva said it is vital to get the gardeners more involved in making the compost so that ways of using it can be thought about. It is incredible how a huge amount of faeces (from a large number of people over several years) composts down to such a small amount.

P1320671 P1320676We really need to find ways to deal with our own waste and close the human food cycle locally and productively. There is a lot of value in faeces as fertiliser and for soil regeneration. Oddly having thought that bacterial infections were the most dangerous part of faeces composting and that was why it is used only to fertilise fruit trees at 7L,  I was told bacteria breaks down in the hot composting processes and is neutralised. It is human made medication that is the problem, in particular the contraceptive pill and long term prescription medicines. These do not compost. Therefore if we are serious about closing the human food cycle we would need to compost faeces with medication separately from those without. What a tangled web we weave!

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