Hi Stew,

Please post the link to the video you mention on triangular solar ovens.

I would not worry too much about ventilation of the oven. If it is not sealed, the humidity will get out. It seems more important to make sure rain does not get in, keep the price down, and make sure that it is easy and practical to use. If the sacks are supported on slats of wood, that wood would likely rot quickly.

What cover material are you planning to use? See my discussion of the advantages of recycling cover material:
www.chekhovskalashnikov.com/human-waste-disposal/
One could get started by including a percentage of dried and decomposed barnyard manure or black forest soil ... or there might be material from previous UDDTs.

I also suggest it is important to have a percentage of ''fluffy'' material that does not break down quickly, like rice hulls, to allow more air to flow through the pile.

What detention time are you looking at in the ovens?

I would suggest no turning of the material, since no one would want to do that. The feces can just stay in the sacks until they are not feces any more.

I think the mentioned expert was talking more from conventionalism than logic. Pathogenic bacteria are much happier in the water and wet surfaces of a flush toilet than in a pile of dry material (esp if there are a lot of soil microbes there) or the the urine funnel getting rinsed frequently with pure urine. Flush toilets can also get plugged and overflow, plus when flushed they send contaminated water droplets all over.
www.chekhovskalashnikov.com/water-sanitation/

Those dry toilets were most likely abandoned because the users never fully understood their benefits and proper use. Who knows? They may have also had design flaws, but most likely it was the lack of socialization and follow-up.

When do you go to Indonesia and how long will you stay there? Any chance of setting up some long-term volunteers to help with follow-up, education, etc.? (They could also help with other aspects of community development.)

Good luck and thanks for this discussion.

Best wishes,
Chris Canaday

Stew, you said some interesting things above:

PF provides a water seal, protecting people healthwise; a large USAID-sponsored project used composting toilets and it went badly; people in Honduras believe water-based toilets are better, they are a status symbol; and UDDTs are a lot more work, and people may not do it, so there is more risk of failure, or work to be done. Also, notes from WEDC and others he has provided, talk about a) must have agricultural use (here we have modest crop growth) and b) bury resulting product under 6" soil. And recently he cites a DNA expert who says there is a chance for cross-boundary transmission of resistant bacteria in ecosan toilets, which wouldn't be a risk for PF toilets. Having said that, I do think that he and WMI will treat this as a learning opportunity, make a fair comparison, and measure things best they can ... treat it as a bonafide learning opportunity.

I'm curious to hear what 'went badly' with the USAID project - but more why you think there is a lower risk of pathogen transfer in a pour-flush system. I'm not sure I've seen anything suggesting this before.

I recognize that the 30-35C diurnal highs in a concrete/stone vault won't be sufficient, and we selected single vault for various reasons, so that's why we're focused now on central storage, aeration/turning and solar heating - to finish the job. I believe acceptance of UDDTs hinges in part on realizing benefits in a short cycle time. So what if we could have good airflow while in vaults, remove half-dried mixes in 2-3 months to central bins, finish the drying and kill (most) bugs in another 1-2 months. A crop cycle (led by urine, adding the fecal humus later) will help acceptance within a year. Training and behavior change will be reinforced. We've planned this as a 2 year project for all the toilets to be constructed and most monitored for quite awhile, retraining as needed. Then a few more years of monitoring.

I'm sure you know, the major risks of a UDDT is in the emptying, so whilst deep burial solves some problems, it doesn't change the fact that someone has to handle the material to your centralised bins.

I tend to agree with Elisabeth - I think it is likely you'll prove that your system is too ineffective/complicated to be scaled up. What then?

In terms of health questionaire protocols, I'd think that would be relatively easy (easier) to do. In India there has been good progress with verbal autopsies (which I appreciate is not necessarily the same thing) to give meaningful data. See www.biomedcentral.com/1741-7015/12/5

Elisabeth,
You ask such good questions!

muench wrote: You said:

An epidemiologist with field experience and health studies is quite skeptical of ecosan, guiding our NGO partner on another project toward pour-flush.

Could you explain a bit more why the epidemiologist favours pour flush? Will you do the same elaborate measurements with the pour flush system to prove that that is safe(r), i.e. in terms of pathogen kill in the pits? Pathogens will survive much longer in those pits than in the vaults of a UDDT. But very often people apply double standards: from a UDDT people expect wonders in terms of pathogen kill, from pour flush not.

That's our Honduras project, and I'm less involved in the project design, Water Missions Int'l is more so. WMI has large project experience in Guatemala with pour-flush, and the epidemiologist health study was there. Here (from memory) are their reasons: PF provides a water seal, protecting people healthwise; a large USAID-sponsored project used composting toilets and it went badly; people in Honduras believe water-based toilets are better, they are a status symbol; and UDDTs are a lot more work, and people may not do it, so there is more risk of failure, or work to be done. Also, notes from WEDC and others he has provided, talk about a) must have agricultural use (here we have modest crop growth) and b) bury resulting product under 6" soil. And recently he cites a DNA expert who says there is a chance for cross-boundary transmission of resistant bacteria in ecosan toilets, which wouldn't be a risk for PF toilets. Having said that, I do think that he and WMI will treat this as a learning opportunity, make a fair comparison, and measure things best they can ... treat it as a bonafide learning opportunity.

I have pointed out the difference between composting and UDDTs, and that such deep burying reduces the rationale for amending the soil; and I feel they are listening.

I just think you should keep expectations in check, which is why I mentioned the case of South Africa where they have given up on the thought that worm eggs can be reliably killed in UDDTs, and they are collecting the material for centralised external treatment instead.
....
But I don't like the high expectations that people have regarding pathogen kill in UDDTs. 6-12 months from now you may come back and be disappointed that the pathogen kill was not as expected. Where I would say, it doesn't matter, actually: Put enough other barriers in place regarding education of users on how to reuse and what and on what crop etc. and then it can still be done very safely.

Sounds like are you saying don't bother measuring bacteria/archaea because, with barriers (lids over poop holes, handwashing, burying in soil?) killing bugs isn't that important. I recognize we can't and shouldn't sterilize fecal product or the environment. But shouldn't we do the best we can?

I recognize that the 30-35C diurnal highs in a concrete/stone vault won't be sufficient, and we selected single vault for various reasons, so that's why we're focused now on central storage, aeration/turning and solar heating - to finish the job. I believe acceptance of UDDTs hinges in part on realizing benefits in a short cycle time. So what if we could have good airflow while in vaults, remove half-dried mixes in 2-3 months to central bins, finish the drying and kill (most) bugs in another 1-2 months. A crop cycle (led by urine, adding the fecal humus later) will help acceptance within a year. Training and behavior change will be reinforced. We've planned this as a 2 year project for all the toilets to be constructed and most monitored for quite awhile, retraining as needed. Then a few more years of monitoring.

I would like to learn more about protocols for monitoring diarrhoea with household survey and diahrroea diaries. When I visited the school headmasters and gurus, they said yes we keep attendance statistics ... and they are always 100%. And measuring worm infections. Can you point me to well-accepted checklists and protocols? I'll also ask the epidemiologist.

Agreed about handwashing with soap - it is being focused on. FYI, the natives came up with their own design of washstand - a large diameter bamboo, all septa removed but the bottom, hole punched in and a sharpened stick on a string, liquid soap on a string. Very nice; I felt much relieved, because they invented it.

It puzzles me a bit that you keep referring to the term of "primitive location". I cannot really imagine what makes a location qualify as "primitive". Perhaps it is one that is more in harmony with nature, without much influence from the outside, with little energy consumption, no plastic waste, no Wi-fi etc.

Touche!
I mention it because when we think of how to do simple things with villager involvement - flash or seal the rain from coming through the vent pipe penetrations, or do surveys, or construct bins, or measure temperature/time/pH - there is no electricity, butyl rubber, plastic mesh, people who write on paper routinely, even screws and screwdrivers. There are none of the resources that appear in the studies you folks site: microscopes, glassware, even marking pens and plastic labels. The villagers have machetes, metal rods, can make woven baskets and cloth; everything else has to come from the small town, and shops there often doesn't have what is needed. So that's why we're aiming for simple ways to measure now, that later will boil down to time, temperature, and following a manual procedure. Hope that answers your point.

Cheers,
Stew

You said:

An epidemiologist with field experience and health studies is quite skeptical of ecosan, guiding our NGO partner on another project toward pour-flush.

Could you explain a bit more why the epidemiologist favours pour flush? Will you do the same elaborate measurements with the pour flush system to prove that that is safe(r), i.e. in terms of pathogen kill in the pits? Pathogens will survive much longer in those pits than in the vaults of a UDDT. But very often people apply double standards: from a UDDT people expect wonders in terms of pathogen kill, from pour flush not.

I just think you should keep expectations in check, which is why I mentioned the case of South Africa where they have given up on the thought that worm eggs can be reliably killed in UDDTs, and they are collecting the material for centralised external treatment instead. (And, many people in South Africa are getting increasigly interested in the new pour flush pedestal by Envirosan, by the way. It is selling better than their urine diversion pedestal, Jaques Rust told me yesterday.)

Don't get me wrong, I am a great fan of UDDTs, I would also mainstream them if I could (that's one reason why I wrote the Wikipedia page on UDDTs together with others). I think they are really a great toilet solution.

But I don't like the high expectations that people have regarding pathogen kill in UDDTs. 6-12 months from now you may come back and be disappointed that the pathogen kill was not as expected. Where I would say, it doesn't matter, actually: Put enough other barriers in place regarding education of users on how to reuse and what and on what crop etc. and then it can still be done very safely.

And there are protocols for monitoring incidences of diarrhoea with household survey and diahrroea diaries. To me, that would be a much more interesting parameter (together with measuring the burden of worm infections). After all, it is the health of the people that you want to improve, isn't it?

And as you mentioned, handwashing with soap is a important barrier against disease, more important than most others, and one that I would focus on.

Regards,
Elisabeth

P.S. It puzzles me a bit that you keep referring to the term of "primitive location". I cannot really imagine what makes a location qualify as "primitive". Perhaps it is one that is more in harmony with nature, without much influence from the outside, with little energy consumption, no plastic waste, no Wi-fi etc.

Hi Chris,

Thanks for the link and quote from your other response. I saw the video if the triangular oven being used, so this helps. Using the sacks as containers from basket to oven then soil-turning is a great idea ... I'll recommend that.

The 5cm PVC perf pipes (as a former HVAC guy) would seem to introduce little air. Natural convection works best vertically, with a heated surface that causes air to first layer, then move upward (chimney effect) - that's why our small team developed the box with slats underneath - airflow can go up the slats, thru the pile, and out the lid. It would be better if we had perf pipes within the pile; but since they aren't available, we may have to rely on turning to introduce new air (aerobic digeston and carrying moisture away).

Perhaps a compromise can be achieved - A frame structure over slats, with 3-5cm holes in the top of the A-frame metal so hot air can get out. We want some airflow, but not so much as to reduce the temperature ... hence the value of trying things, and having (say) hourly temperature measurement.

The relationship with LBL/DNAE started by my reading an article in SierraClub mag on fancy BMG-funded toilet (well that's not likely to be widely adopted), which had in the last paragraph a reference to Haiti's SOIL using low cost DNA testing. Inquiries led to Sasha, DNAE, John and long conversations. DNAE is going thru a reorg and realignment, so taking on new project monitoring may not be timely, but I'll mention it next time we talk.

Their long-term goal is to use sensors + smartphones to allow for a remote "lab" to extract samples, either measure onsite or at one of many universities that subscribe to the phylochip approach. I'm very excited about the prospect of using DNA to truly measure the bacteria and archae that are present; but this is new enough that I'm a bit skeptical. A "show me" attitude like in Missouri, seems appropriate.

I agree that having each stage, and longitudinal study, is beneficial. But in this locale, it's gotta be simple rote procedure, not time intensive. Perhaps you and others can help us develop the protocol for that aspect of our sample extraction and testing? That would be lovely.

Cheers,
Stew

Hi Stew,

Congrats on this great project. I especially look forward to seeing your DNA results. As far as I know, this is the first time that Metagenomics is being applied to pathogen die-off in feces, so this is very important. If budgets and logistics allow, it would be great to take samples every week or every month, starting Day Zero, to document the whole process of microbial succession and know when, under those conditions, is it safe for use in agriculture or for reuse as cover material in UDDTs. (Would DNA Everywhere like to come to look at our UDDTs in Ecuador? How did you manage to get them on-board?)

It seems the solar oven could be much simpler and more practical than the illustrated barrel. I like the tin-roof option, but in an A-frame, as I mentioned here:
forum.susana.org/forum/categories/34-uri...rview-on-uddts#11081
''I can imagine building a long A-frame with a metallic roof, maybe an equilateral triangle in cross-section and 2 m high, made such that sections can be propped open for sacks to be placed inside or taken out. The temperature should get quite hot inside, especially if the metallic roof is painted black, and the required detention time for pathogen die-off might be one month or even less, and could be determined via searches for Ascaris eggs (and envelopes of plastic mesh holding Ascaris-laden feces could be added, if the users do not have Ascaris). The metal roof would protect the polypropylene sacks from solar UV, thus the same sacks could be used year after year.''

I would use long-lasting Galvalume metallic roofing and paint it with non-glossy black paint (unless there is a more ecologically friendly way to blacken the roofing) and position the structure from North to South, so that it receives full morning and afternoon sun. The floor could be simply a layer of large rocks (and a small birm around the perimeter could prevent water from entering or leaving).

One of the big advantages is that the rice sacks can be stacked straight into the oven, without having to open or empty them. The sacks could just be pulled out of the baskets, for reuse of the baskets in the UDDTs. Ventilation could be increased within the pile of sacks by putting perforated 5-cm PVC pipes between layers of sacks.

On the socialization front, I think it is key to use the analogy of jailing up dangerous enemies ... so this could be the theme of games and skits (impromptu dramatization) to help children and adults to understand this concept. A narrator could even play up the importance of detention time (or heat, etc.), after which those previously crazy and dangerous enemies are now converted into friendly allies for the growth of crops.

We hope you find time to write up the process and keep us informed.

Best wishes,
Chris Canaday

Seems to me that's a very useful thing to do Stew. I honestly can't see the problem.

That's correct, Joe ... this is a verification that the project is sound ... leading to simple, repeatable methods that are low tech, and which poorly educated villagers can follow, indefinitely.

I hope this will be the 3rd of many sanitation projects in Sumba - so the measurement tools will be useful in refining approaches in the upcoming villages.

So ... for the folks who have contributed their ideas, thank you!

I've just ordered the iButton Thermochron DS1921G which does either time-temp or histograms around 2C degree measures, will last for a few months before remissioning, a downloader-reader to shuttle data to the office, software to transfer data into excel sheets; and I have tech support available from Embedded Data Systems.
I decided to forego the Hobo system (wires, fragility, expense) and also the bluetooth wireless iButton reader (too few sold, adds another level of complexity).

All will arrive next week, give me a chance to practice and put together images or video clips to train the staff in Sumba. Total cost for the package under $1000.

I don't think they are planning to use all these instruments in real life, Elisabeth. As I read the proposals, the idea is to do some preparatory work with the instruments which means you can validate the system effectiveness.

Also I'm not sure whether they are talking about household-level treatment units. It seems like they are talking about collecting the UDDT wastes for centralised treatment.

And just to reiterate once again - feeding faecal waste to insects to feed to animals is not a legal problem in South Africa, but is meeting significant legal hurdles in North America and Europe.

muench wrote: Thanks for the detailed description, very interesting. However, are you sure it is not a bit of an overkill what you are trying to measure there?

To be candid, no, I'm not sure. I grant you the villagers are not interested in research; and the toilets are merely devices to separate feces, collect it for later central disposition.

But from what I've read here and elsewhere, there is not a simple reliable method we can recommend to the villagers which will assuredly kill all the bugs, including ascaris. These people walk barefoot, rarely wash hands (our training will change that for many), and children play everywhere unprotected. Without lab tests to verify (or in our case hopefully phylochip verification), and a clear history of time-temperature for the feces that is both in the baskets in home/school vaults, and the central piles that we heat up with solar collectors - how can we objectively assure safety?

Our Rotary standard is to leave the project totally self-sufficient, managed by beneficiaries, continue monitoring for up to 5 years. What will we monitor in this primitive location, that is a real measure of success? [Incidents of diarrhea can't be recorded reliably. Missing school and work is too indirect and sporadic.]

An epidemiologist with field experience and health studies is quite skeptical of ecosan, guiding our NGO partner on another project toward pour-flush. At least we now have a careful trial comparing pour-flush vs. UDDT, 40 of each, develop balanced training program, satisfaction surveys, and give them choice to change at the end. It may lead to an IRB and published paper. Then the "real project" to build toilets and do community training and behavior change will follow.

If UDDTs are to become accepted by school and health communities, and supported more broadly, I think they need to be simpler, more consistently implemented, output and local conditions need to be more easily verified with objective data. Parts like ecosan pans need to be prolific in the usual supply stream. At present there are lots of different approaches, often using homemade assemblages, many papers about the various approaches - but little in the way of training materials, supply-stream parts, and little in the way of simple guidance for how lay people can simply do a UDDT project. I personally think UDDTs need more mainstreaming.

Christoph, did you mean one of these papers which Chris Buckley co-authored on various aspects of UDDTs:
www.susana.org/en/resources/library?search=buckley

Personally, I think all these measurements that you are planning to do, Stew, might be interesting from a research perspective (if someone is doing his or her PhD on it), but in real life it's a total overkill.

We know roughly from common sense what UDDTs and simple driers can and cannot achieve. You will find they give you some pathogen kill but not complete pathogen kill.
Let's not expect too much from UDDTs and small scale household level treatment units. Think about what you are comparing it against and most likely the situation is much better than before, i.e. open defecation or pit latrines?

A UDDT is still (only) a toilet, not a fancy always-reliable pathogen destructor. See also what we wrote on the UDDT page in Wikipedia and in the GIZ Technology Review.

Related to this: At the FSM3 conference that I am attending this week, Dave Wilson from eThekwini Municipality stated that they (the municipality) have recently decided to empty all of the 80,000 UDDTs in their area every two years free of charge.

Formerly, it was expected that the households should empty the faeces vaults themselves. But as they found that pathogen kill is not that far advanced (see what I said above), also after burying of the material on the plots, and to make it fair compared to VIP latrine users (who also get a free emptying service from the municipality - every 5 years), they decided to change their policy.

So they are now going to collect the dried faeces material and then treat it at a centralised level. They are going for black soldier fly treatment (research funding by Bill & Melinda Gates Foundation), making chicken and fish feed - apparently OK with the South African legislation. But that's for another thread.

My point is that when you collect dried faeces from the UDDTs and take it to a more centralised facility, then you have some certainty over pathogen kill and there it makes sense to measure all sorts of parameters in detail. But at the household level? I don't think so. Unless it is part of an interesting research project. As you said yourself, let's not expect too much of the UDDT users, they just want toilets that don't smell and are convenient to use, not be part of a research projects - I would assume.

Cheers,
Elisabeth