Hi Chris,

No, not involved in that India project. One Rotary WaSH project in India, more often in Indonesia and CenAm, one is percolating in Tanzania.

I've followed some of your posts here, viewed website and video ... very informative!

Idea of wax or sealant on bamboo is interesting; might extend life 6-12+ months. The villagers came up with the idea of gedek on bamboo frames; but gedek (aka kedek) is like dried palm fronds, will rot too quickly. We are now looking for the woven plastic bags. No PET beverage bottles in Sumba villages; quite primitive rural area, as much or more so than sub-Sahara.

I see you use dried humus (re-purpose) to be the drying carbonaceous material for next round of feces; how does that work? As well as firepit ash, sawdust, minced leaves?

I read lots on 6-12+ months for dehydration, some speculation on shorter periods ... but being a biologist, how does one really test to verify helminth egg inactivation? Looking a samples under microscope doesn't tell, does it?
And have you used 3M Petrifilm on a suspension made from the material to count e.coli or coliform CFU's?

Stew

Hi Stew,

Recycling of cover material is imminently practical, as no solids need to be transported long distance, to or fro, with who knows what vehicle and who knows what petroleum (or donkey power). It also inoculates the new feces with at least some of the same soil microbes that broke down the feces of the previous cycle. If we have reliable treatment (via heat, sun, thermophilic composting and/or long storage), no significant amounts of pathogenic microbes will remain and there is minimal health risk. Remember that any system can be used incorrectly (like having flush toilets dump straight into rivers where people swim and drink).

In my experience, recycled cover material controls smell and flies much better than the mix of sawdust and ashes that we used before. I am also convinced that this gets even better year after year, likely due to accumulation and natural selection of the soil microbe species present and potentially even some evolution, given that microbes evolve so quickly. See the scientific papers cited in this interview, for support for the idea that finished compost is one of the best materials for covering the smell of composting or landfills:
www.chekhovskalashnikov.com/human-waste-disposal/

The limitations to this recycling are mental and cultural, due to fecophobia (irrational fear of feces) and the illogical belief that "once feces, always feces" (and that the entire planet is gradually being converted to feces), since no one would identify its origin by smell, color or texture. In addition, it mostly consists of the original cover material, since the feces largely disintegrate, with their water evaporating out and their microbes killing each other until they occupy very little volume.

If users are concerned about pathogens still persisting, they will remember to wash their hands, which they currently often do not. The recycled cover material can also be added mechanically, avoiding direct contact with the user.

Yes, one can check "finished biosolids" for Ascaris Helminth eggs by looking at them with a microscope and these eggs are quite characteristic, with their golden color and bumpy surface. There are techniques to concentrate the eggs and increase one's chances of finding them, which is the subject of another current thread:
forum.susana.org/forum/categories/26-hea...ce-a-better-way#8176

Last year, a student intern did one, isolated 3M PetriFilm trial for E. coli in the one-year-old recycled cover material by mixing it into water and applying the normal procedure for water samples. During incubation, 2 blue spots developed, indicating that 2 E. coli bacteria were present -- roughly an order of magnitude acceptable for a swimming pool. (I can look up more detail on this trial, if anyone likes.)

Update. I no longer mix wood ashes into the recycled cover material, since I do not want to kill the beneficial microbes. Also, most people do not have access to large amounts of ash ... which might best be used as fertilizer (including mixed with urine). I do mix in some 10% rice hulls, to replace lost volume through decomposition of the sawdust originally used as cover material and to increase air flow through the pile. (Other resistant, bulky, food-processing wastes, such as crushed egg shells, squash shells or manioc fibers, could also be excellent to mix into cover material.) I also sometimes replace lost volume with dry organic soil, in order to maintain a one-year detention time (longer than probably necessary, for peace of mind and further drying).

There is more detail on this recycling in previous posts:
forum.susana.org/forum/categories/17-fer...rt-of-processing#505

forum.susana.org/forum/categories/17-fer...imit=12&start=12#531

Thanks for asking, Stew. Keep sending any questions you may have.

Best wishes,
Chris Canaday