Watershed Management Group just received a permit from Arizona Department of Environmental Quality (ADEQ) to install and monitor 24 site-built composting toilets in southern Arizona. Currently ADEQ allows only NSF approved (and those listed specifically by ADEQ) composting toilets are allowed for use. The 2-year composting toilet pilot program is part of a Soil Stewards educational grant funded by U.S. Environmental Protection Agency. More information regarding the composting toilet designs developed for the pilot study can be found here: watershedmg.org/soil-stewards.

The 24 composting toilets will be implemented at a range of sites including the Community Food Bank's Las Milpitas farm, Watershed Management Group's Tucson office location, and a number of individual home sites sprinkled around urban Tucson and rural southern Arizona. The two primary systems to be monitored include the Omick Barrel composting toilet, 19 systems, and the Nogales Double Chamber composting toilet, 5 systems. In addition each of the two systems will include an option to integrate urine diversion with the composting toilet system.

Monitoring of the batch-style composting toilets will include social behavior and barriers, general CT system performance in terms of vector control (e.g. flies), ease of use, odor control, durability of system, and effectiveness to remove e.coli bacteria after the composting phase has been completed. The monitoring process will be utilized to refine the system designs to be incorporated into standard design details. The standard design details along with the monitoring results will be submitted to ADEQ to become reference designs which will allow for future permitting opportunities for site-built composting toilet systems.

This is an important project ... and it is in a nice, dry climate, so there should be considerably less risk of smell and flies.

The link to your webpage does not work, so please check on that.

You may find useful some of the site-built dry toilet features that I apply here in Ecuador (inodoroseco.blogspot.com/).

I would like to recommend you experiment with different easily available cover materials, including sawdust, dry soil, ash, some fine-textured (or ground-up) agricultural waste (potentially converted into biochar) and mixtures of these. (You may also like to consider the re-use of treated used cover material, to eliminate the need for so much transport and for microbiological benefits; see my post on this forum #505
forum.susana.org/forum/categories/17-fer...effort-of-processing). One could potentially even do a study with dogs, to see which cover material most effectively disguises the smell of feces (since you have connections with universities).

Please let us know how things go.

Best wishes,
Chris Canaday in Amazonian Ecuador

I discovered the link was broken as well, but it is only because there is an extra period at the end. If you delete the period then it works fine.

Hi,

Deleting that extra period, I was able to see your designs and they are very interesting.

The Nogales Model is a standard, 2-chambered UDDT and should work fine, if the users are "with the program", always have plenty of cover material, and maybe have a stick to knock the mountain over from time to time. In such a dry climate, one of the main reasons for urine diversion may be to make better use of it as fertilizer.

The Barrel Model seems more experimental and overly labor-intensive for the user. The average person will not want to work each of the three barrels (including the active one!) with the compost crank every couple of weeks.

How long has the urine diversion system been tested? The use of such thin rubber fuel line for the urine seems risky in terms of plugging. Does women's urine really tend to go into that off-the-shelf automotive funnel (aside from the few normal drips farther back)?

Suggestions:

//If you collect the toilet paper separately (to later be burned, converted to biochar, buried or composted), the user would not have to squirt water to allow it to decompose, and the pile would stay drier and there would be little need for cranking.
//A false floor and a pipe would allow the bottom to ventilate and stay aerobic, thus eliminating the need for cranking, especially in such a dry place.
//If you include soil or compost in the cover material, there would be a broader array of microbes to decompose the feces (even if drier than the normal compost pile).

Best wishes,
Chris Canaday

Thank you for your interest and suggestions. We are about mid-way through our pilot phase of evaluating the two site-built composting toilet systems and urine diversion. Some minor upgrades have been made to the systems to help 1) improve user like-ability with the interface and 2) reduce nuisances such as with fungus gnats, and 3) appease regulators by directing urine to subsurface leaching rather than collection systems.

Updates to the barrel systems can be found at omick.net

We are currently drafting up reference designs to submit to the state regulators. When these are compiled along with summary of evaulations we will be posting them on our website to share: www.watershedmg.org/soil-stewards

Regards,
Catlow