Is there a technical paper detailing the composting toilet recently constructed near the Community Garden? Also, an estimated cost of construction for the ECHO toilet available?
While we do not have a technical document detailing the specific design of the composting latrine in the Community Garden, the link to the resources Steve posted has the general information needed to design your own. This latrine utilizes a dry composting method, thus it is designed to separate the urine and feces. Typically it is recommended to allow the urine to age one month to break disease cycles, but then it can be diluted and used whenever needed. The feces must sit in the vault for at least one year. Sawdust, wood ash, dry soil, or some other sort of natural desiccant is used to cover feces after each use. This dries down the feces which limits odors and pathogens, while also adding carbon to aide in the composting process later on. After a year of “aging”, the feces then is put through a hot (thermophilic) composting method to kill any harmful pathogens that remain. “The Humanure Handbook” is a valuable resource for understanding the ins and outs of breaking disease cycles in this process.
Just to give you an idea on a cost estimate for building a similar sized latrine (double vault) with materials available in SW Florida, the rebuild that we did was somewhere around $2000. They can be done for less, especially if you have access to natural building products. Our higher cost was also due to building it for “heavy traffic” use and the increased roof area. We intentionally sized the roof for adequate rainwater harvesting to supply our handwashing station on the side of the latrine.
While it’s nice for us to have all those extras to accommodate for tourists use, the real necessities boil down to a sturdy vault (needs to be well sealed to keep from contaminating the surrounding area), some sort of walls for privacy, and a roof that will keep the structure dry.
Hope this helps!