An UDDT seems to be the most environmentally friendly alternative, but for some contexts, a composting toilet might seem preferable (like rentals, or camping sites where people don't always remember to use the toilets correctly).
What are the disadvantages of using a composting toilet in terms of:
- Waste generation: does the composting chamber generates black water? gases?
- Odour: does the presence of moisture and greater humidity contribute to the generation of unpleasant odours?
- Maintainability: how often do you have to take care of the compost?
For what I have gathered, a double chamber UDDT needs to be maintained once a year, does not generates waste and, since it's dry, it doesn't smell bad. Can all these characteristics be achieved by some composting toilet design?