I want to built a composting toilet. What are the main construction aspects to be considered? Does anyone have a manual to share? I am especially interested in construction schemes which include the excreta on site.
We live in a household of 5, and have 2 composting toilets. Whatever solution you choose, the biggest hurdle we have found is the cost of heating the waste to increase the evaporation rate. As we live off grid, having heaters and fans running 24/7 does consume a fair amount of the power produced by our PV system.
The waste pile must be aerated every couple of days to avoid anaerobic decomposition, we add about two parts lucerne straw to one part faeces.
The peat produced is very good and we have been using it for years to fertilize our vegetable gardens. We take the waste from the toilets every couple of months and put it into our green waste pile for about 12 months before digging it into the garden.
Although I have not made my own composting toilet, I have been interested in the idea. I've heard that waste can be collected in a bucket (typically a 5-gallon) beneath the toilet hole. Peat moss makes a great compost material- just use it as an additive to the waste.
I have heard you can also use sawdust or woodchips to eliminate odors.
If you have a sufficient yard area, a composting dry-toilet can be easily built as a very simple facility.
create a composting pile - you will require at least 2, and better 3 composting piles in the long run.
buy 2-3 big square flower-pots, and have a toilet seat fitted on top of it. The seat can easily be removed from the flower pot for disposal to the composting pile:
I started this home and it works for now. I installed the thing outside in a secluded place for intimacy. My outside light allow using it at night too. Consider hiding your place it behind curtains.
The thing is my installation doesn't dry. For it not to stink, I pile up sand, dried leaves and saw dust on top of it. I have to use mowed grass to clean the bin after disposal.
One method of making a composting toilet is to connect the outlet of a regular flush toilet to a ~1 cubic meter flowbin (just a container with an inlet at the top and outlet at the lowest point). And then you fill it a third to half way with mulching material (woodchips work well) and a kilogram of earthworms.
What will happen is the solids will get trapped in the flowbin by the mulch and get processed by the earthworms and the liquids will drain out. The liquids should then go into a greywater system.
We've been using this method for 2 years by ~3 people/day (sometimes 10-12 people over the course of a week) and haven't had to empty the flowbin yet. When it comes time to empty, we'll stop using it for a bit so that it can be fully processed by the worms. Or at least enough that it's not a horrible job. How long that is, is still to be determined.
I would say only do this if you're somewhat familiar with using composting toilets already (a good one to start with would be a dry composting toilet). Also note that there is the potential to kill your earthworms by taking strong worm medicine internally.
The performance of the system is brilliant. There is literally no smell unless you stick your head right inside the flowbin. And it functions just like a regular toilet that everyones used to.
Sources - Personal experience and "Solviva" by Ana Edey (the design comes from this book)