The compost heater silo can be expanded to an integrated compost heater toilet system. The system serves as a heater and a toilet at the same time. The silo is filled with waste biomass (chipped wood, etc.), which is the basis of the wet decay process. Additional biomass (feces and urine) can be added. The decay process breaks down the excreta before it can reach the bottom of the silo, so it works as a small biological clarification plant.
The combination of a compost heater silo with a toilet function provides a number of advantages:
- No water flushing system is required. This saves a lot of fresh water.
- No connection to a public sewage canal is required, because this is a standalone system.
- The resulting inorganic matter (water, CO2) does not polute the environment. The outlet water contains valuable minerals and can be directly used as liquid fertilizer for the garden.
- The additional biomass adds to the heat energy for the house warming.
- If build correctly, the slight vacuum from the ventilation pipes prevents any smell in the house, which is better than any other toilet system.
For convenience the toilet input is located on the upstairs floor, where the regular biomass inlet is combined with a toilet seat. In contrast to a dry toilet the excreta are processed in a wet environment and therefore are much faster decomposed.
Preventing bad smell[edit | edit source]
The toilet seat is made airtight to seal the silo when the toilet is not used. The moment the toilet lid is opened we can create a directed airflow to prevent an inflow of bad smell into the toilet room. The direction shall go from the toilet room though the open toilet seat into the silo and then out with the outlet air.
The door of the toilet room should be made airtight too. This ensures to uncouple the airflow from other parts of the building, where vacuum generating appliances are working, e.g. an exhaust hood in the kitchen.
Passive ventilation is possible at cool outdoor temperatures by stack-effect if an additional air inlet pipe to the toilet room is installed. The additional airflow starts when the toilet lid is opened and stops when the lid is closed.
In case of poor natural ventilation the system can be equipped with an additional forced ventilation device (e.g. tube fan) in order to provide positive pressure in the toilet room. This device needs to be working only during the usage of the toilet.