Today I emptied the bin from the composting toilet. Nothing remarkable in that—I do it once a month. What was remarkable was that there were worms in it. How they got there is a mystery. They were doing a good job though. Already part of the contents was nice and friable.
I should digress here to explain the operation of the system. The composting toilet is a RotaLoo. It sits below the bathroom floor directly under the toilet. A 10″ diameter pipe (yes, I know we’re metric, but I grew up with feet and inches and I like them) leads from the toilet pedestal into the fully enclosed chamber in which sit, on a rotating turntable, 6 triangular bins, each holding about 30 litres (I know, I know, but I like them better than gallons). As a bin is filled it is covered with organic material, in this case mulched bracken fern, and rotated to the left, thus bringing the next bin into use. The solid material stays in the bin; the liquid filters through holes in the bottom of the bin and into the bottom of the outer chamber. A fan drags air over the system (providing aerobic bacterial breakdown) and evaporates the liquid, leaving a crystalline deposit of urea on the bottom (more on that later). A door on the side of the chamber provides access for changing bins.
The upshot of all this is that it’s physically impossible for any worm to enter the chamber and the bins.
It takes the two of us about a month to fill a bin. The full bin is rotated to the left. Next month, same again. So each full bin stays in the system until it comes round to number one position again, a period of about 6 months, at which time it’s emptied and the empty bin re-enters the system. By that time the contents have composted and the volume has dropped to about 60% of the original. Still doesn’t explain the worms.
In the bathroom, we keep a bowl of organic material with which to cover each ‘deposit’, mainly to provide aeration of the contents. Initially a bale of wood shavings was purchased to do this job. In keeping with the desire to be self-sufficient, I began using mulched bracken fern which grows on the property. It is stored in a large outdoor open bin which also contains compost …….and worms. The bracken sits on top of the compost, acting as a mulch to stop it drying out. There are never any actual worms in the bracken—it’s too dry and open-textured, but there could be worm eggs. That’s the only explanation I can think of. The eggs hatched in the bin and……….there be worms.
On one occasion I actually considered adding worms to a bin as I close it up to be rotated. But I wasn’t sure if they’d survive the contents (pH could be a problem) or the heat that must be produced as breakdown proceeds. I was also worried that they’d get through into the large chamber, drown in the liquid and block up the plastic tube which I use to drain out the liquid.
And this is where I explain “more on that later”. Initially we used the fan all the time. It soon became obvious that it wasn’t evaporating the liquid as fast as we were producing it (probably because the air being dragged over the bins wasn’t warm enough) and liquid was building up in the bottom. So I drilled a small hole in the side of the main chamber and inserted a 5mm plastic tube. I now run off the liquid (nice rich nitrogen fertiliser) and use it diluted 1:10 to water the vegies. (You’ve never seen such green lettuce). It’s stored in an open bin out in full sunlight. I reckon the UV will dispense with any problematic bacteria. And all the vegies are thoroughly washed before being used.
And the worms seem happy.