Dear Chris thanks a lot for those links. I was looking for tha article since a longer time, had it once but somehow I lost it. There was something tricky about reading those data but I can´t remember the trick. In the Ecosanres group there has been a larger discussion about the higenic point about 1,5 years ago. Do you have acess?

Yours
Christoph

Chris,

The Howard Higgins system generates and reuses cover material in 60 days!
This is the key to no vent pipes, solar hook up etc .,etc.,

Andrew Loxham of New Directions Foundation is also working on the pedal/lever operated organic flush system, for posh loos. The basic model is already there from a Finish company.

All: Many thanks for your input thus far- it'd be great to keep the discussion going!

Christoph: To your question regarding the correlation between feces reuse and helminth infection, attached are the 2003 and 2006 papers directly addressing the issue. In short, yes- they did find a correlation of composting latrines and increased helminth infection over pit latrine users whether reuse was practiced or not.

Has anyone else seen similar studies confirming/contrasting these observations?

Best,

~Chris




Note by moderator: We deleted the second attachment because it looked like an article with copyright, however you can can use the following link instead to view the full version of the article: onlinelibrary.wiley.com/doi/10.1111/j.13...006.01737.x/abstract

Dear Chris,
you mentioned

"Health risk is a concern as Corrales et al (2006) found that ecosan users in El Salvadore practicing reuse had quite higher rates of helminth infections than those without improved systems."

Below I copy the results of the google search for the mentioned atricle:
onlinelibrary.wiley.com/doi/10.1111/j.13...56.2006.01737.x/full

Results:  Users of solar desiccating latrines had the lowest prevalence of enteric parasite infection. Double-vault, urine-diverting desiccating latrines effectively reduced the transmission of some pathogens, but may not achieve the conditions sufficient for the complete destruction of the more environmentally persistent pathogens, Ascaris lumbricoides and Trichuris trichiura. Contact with inadequately treated latrine biosolids was associated with an increased risk of Ascaris infection.

Conclusions:  Solar latrines were associated with the overall lowest prevalence of enteric parasitic infections. Members of households where latrine biosolids were used in agriculture had a higher prevalence of infection than those where biosolids were buried. We therefore recommend the promotion of solar latrines in rural areas of El Salvador over other dry sanitation systems, and recommend that stored biosolids not be used in agriculture.

Unfortunately I do not remember the full article any more. Reading the summary I got the impression that in general members of households where latrine biosolids were used in agriculture had a higher prevalence of infection than those where biosolids were buried, so no relation to Ecosan or not, just to use of biosolids (of whatever source) versus biosolids buried. That is very well known.
Concerning your question about the added value of the use of feces. We do have the experience that in very sandy areas or rocky areas the use of the treated feces is very welcome. In these areas it seems to have an interesting effect.
To Chris Canaday: Chris, I personally dislike the “reuse” of feces as cover material. It might theoretically be possible to do so without danger when you use a biologically dead material, as it is done in the ECODESS experiences (they put lots of lime = pH very high = no biological activity). In this case there is no possible influence on the inoculation and I admit it is only my personal barrier that I for myself would have a problem to use it. But if there is still biological activity, in this case I think it is dangerous to use the material. For me the circuit would be too short.
My favorite is the centralized collection and treatment of material. By this you can afford to obtain a good control of the process.
Yours
Christoph Platzer

The main agronomic benefit from feces is the improvement of soil structure (increase of organic matter content of soils, build up of humus), and only to a lesser extend the fertilizing effect from nutrients contained in feces.
This benefit will be greater in poor soils, and much less in soils already rich in organic matter (as it is the case in our projects in Moldova, where they have rich Chernozem soils).

The main problem regarding cost effciency of feces reuse is that the quantities are quite small, and to have real effects in improving soils addtional use of compost of other organic materials would normally be needed.

I agree that in real life it is more useful to decide the question of reuse or containment (burial etc.) of feces based on practical criteria rather than on the theoretic benefits. If safe reuse is difficult to achieve and users are so not enthusiastic, I also would favor burial of the stuff.

Florian

Dear Chris,

Your research seems to be very solid.

According to various publications, feces hold nearly all of the disease risk, while only holding 10% of the nutrients.

I suggest that our best reuse of cover material with a small percentage of dried feces (after approximately 6 months in tropical countries or 12 months in temperate countries) is to use it again as cover material. Advantages include
--Not needing to ever search for more cover material, after the initial 7 or 13 months (this is key since many UDDTs fail due to lack of cover material).
--Containment of any potential lingering pathogens (as you say).
--Fewer smells and flies (at least according to my subjective experience).
--Innoculation of the beneficial soil microbes that decomposed the feces of previous cycles.

Richard Higgins (on Ecosanres yahoogroup) and Juan Carlos Calizaya (CENCA and ECODESS publications) promote this recycling of cover material.

This will be more acceptable to the general public when a pedal-operated mechanism is developed to bring more cover material and take the feces away, as Fioravanti, Henry and I are working on.

Best wishes,
Chris Canaday

Some questions on my mind that the Susana community will hopefully be able to help with.

While we've seen a plethora of studies strongly demonstrating the benefits of urine reuse, there are very few that make a case for the marginal benefit of dry feces reuse. Of the studies we could find, the following showed no statistically significant difference in crop yield by dry feces addition.

• Guzha et al's 2005 study "An assessment of the effect of human faeces and urine on maize production and water productivity"


• Mnkeni and Austion 2009 "Fertiliser value of human manure from pilot
urine-diversion toilets"


• As well, Kutu et al. (2010) observed an increase in spinach yields only when faeces were applied in combination with urine.

Health risk is a concern as Corrales et al (2006) found that ecosan users in El Salvadore practicing reuse had quite higher rates of helminth infections than those without improved systems.

While I'm sure there is some agricultural benefit given the relatively high P and K in feces, the question on my mind is: Is it worth the effort, cost, and health risk to advocate fecal reuse in a rural setting when containment (by burial or other means) is usually an option?

Wouldn't urine reuse and fecal containment usually be the better strategy?

What am I missing or forgetting about in this analysis? Has anyone had their experience teach them differently?

Thanks!