Finalizing the composting toilet 2017-01-09
BaanRimNaamCompostingSewage
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One of the most interesting aspects of moving in to BaanRimNaam was getting the composting toilet ready for actual use. Unfortunately, I left this for after dark, so the mosquitoes were chewing me up, but the process was fairly straightforward (albeit somewhat improvised).
For the tank down below the house where the composting will occur (at least until we dump the “humanure” into a larger composting pile), we grabbed some plant matter to get things started.
First we started with the empty tank. This is just the empty tank we built as part of the plans we bought from Biorealis in previous composting toilet posts. In summary…

  • it is basically just a 200L (55 gallon) plastic drum cut to the size that can fit under the house
  • it has a custom tray added to the bottom and pipe in the center that we cut holes in to allow air to flow throughout the humanure materials
  • and there is mosquito netting around the holes to hold the composting materials in (and possibly vermicomposting worms in the future)

The whole thing was made from plans we bought from Biorealis with basically only leftover scrap materials from construction of the houses.

We laid down the straw on the bottom to make a sponge like bed to absorb any liquids that might drip down. 

Then we improvised and took some partially composted material from our composting beds to get the organisms seeded that will compost the humanure:

(The compost is actually about 10cm thick, but there was some straw mixed in, so don’t be confused and think there is only a thin layer of this black compost material.)

With that, it was ready for wheeling back under the house on its dolly and rails:

Then close and lock the doors and it was ready for use!

This is a picture from above at this point. (Don’t worry, this is a brand new toilet that hasn’t been used yet. You are just seeing the plant composting materials from the bathroom above. I will spare you any further pictures from this perspective in the future 😉

The yellow peeking into view in the upper left was the urine diverter funnel.

Finally, we grabbed some loose sawdust from the construction of BaanLoiNaam to use for “flushing the toilet” and filled up a medium large plastic garbage bin with it:

This sawdust is kept in a bucket next to the toilet along with a coconut husk scoop:

When the bucket empties, it can be easily refilled from the trash bin.

The sawdust acts as several things:

  • a bunch of plant material to provide carbon for composting (the ideal ratio is about 25:1 carbon to nitrogen)
  • as a cover for the humanure to prevent flies from growing in the pile
  • and finally as a deodorizer to prevent odors from escaping in to the house. (This is a pretty important one!)
The deodorizer effect worked so well that even though we hadn’t hooked up the exhaust fan for the chamber below the house for several days, there was no noticeable smell coming up at all.

Nonetheless, we eventually hooked up a 12V DC exhaust fan under the house:

This is just a spare 10W 12V computer case fan we had lying around. Because it is rated at 12V and our solar system runs at around 24V, we had to use a cheap step-down converter. (The same one we use to step 24V down to 5V for the light controllers.) This was for the best, since the converter is adjustable, and at 12V it was really a bit too loud given that my head is probably only 1-2 meters away when I sleep at night. So we trimmed the voltage down to about 6V and it now runs completely silently.

Here is a wider view. It basically hides underneath the far corner of our porch.