Dear Colleagues,

Here is a picture of my colleague Patrick Onyango (GIZ) explaining to colleagues from the water utility (Oloolaiser Water and Sewerage Company) about UDDTs in peri urban areas. The book is truly a gift that keeps on giving. Once more thank you so much particularly to Christian and Elisabeth for putting so much effort in book.





Best regards,

Doreen

Dear All

We wish to bring to your attention of the addendum which has now been inserted at foot of the Technology Review of Urine-diverting dry toilets (UDDTs) in the Africa Water, Sanitation & Hygiene Vol.8 No.3 June 2013 edition.

The addendum is even more pronounced as the Review has been extracted from the magazine, posted separately and titled June 2013 pages 18-22.

Kindly view the revised extract in the attachment. The revised copy of the complete publication also appears in our website http://www.afriwater.org/publications.

Kind regards

Mwaniki

Hi Everyone,

(I will try to recreate my message, which got lost, as the system had logged me out. Very frustrating. Of course, I should have copied it first, but the screen said I was logged in.)

Congratulations on this new version of the GIZ UDDT Review, as the English has improved significantly.

Some of my previous points have been integrated to some extent, but the text still portrays single-chambered UDDTs as a second-class system that produces inferior and more dangerous biosolids.

Why not simply state that this is due to the use of sealed, air-tight buckets that do not allow humidity to evaporate out, nor oxygen to filter in? One could also suggest that 10 cm of soil be added before storage without the lid, protected from the rain. For more security, one could tie a plastic mesh around the mouth of the bucket, to prevent emergence of flies or spillage.

Here are a few suggestions on the text:
(1) "asfresh" needs a space, to become "as fresh".
(2) Footnote 20 seems to cite my blog, but its address is inodoroseco.blogspot.com , not .de. Also, it would be more correct to cite the scientific papers I provided previously.
(3) At one point, it mentions a "buffer", between the bench and the receptacle. Do you mean a "chute"?

Elisabeth mentioned the following in a recent email: "It’s true the interchangeable containers that are mentioned in the document is primarily with plastic buckets (although we did mention sacks as an option). I discussed your proposals with the other 2 authors, but they felt that we should focus on the systems that are proven at a rather large scale – as our focus was on scaling up. That’s why we often referred to the Durban case or also Peru and Bolivia (El Alto). For your system, it was felt that the numbers was not there to prove how it works on a large scale where you don’t have dedicated users."

In response to this last point, we have thousands of non-dedicated users at the Omaere Ethnobotanical Park, many of whom have never seen this system before. It is true that I mostly change the sacks myself, but sometimes interested volunteers do so with no problem. In scaling up, trained staff would perform this simple task.


I would also like to mention that with the Pachamama Foundation we have built 25 UDDTs with interchangeable sacks in 2 indigenous Achuar communities in the Amazon. All of the users previously defecated in the open. They were very doubtful about this at first, but now they like and use our system and have no trouble changing the sacks. Only a couple of families still need to "get with the program".

This UDDT Review is an important document, with much effort from many people. With these last few corrections (from my perspective), I could recommend it to interested persons to read.

I would like to close with a thought-provoking quote from an analysis of Human Microbiome studies, which is very interesting from the perspective of sanitation (Courtney J. Robinson et al. 2010. From Structure to Function: the Ecology of Host-Associated Microbial Communities. Microbiol Mol Biol Rev. 74:453–476.
www.ncbi.nlm.nih.gov/pmc/articles/PMC2937523/):

"WAR NO MORE: HUMAN MEDICINE IN THE AGE OF ECOLOGY

... In this final section, we propose how consideration of the ecology of the human microbiota can help to inform future approaches to the prevention and management of human disease.

Understanding the role of microorganisms in human disease represented a revolution in medicine... However, this also led to the paradigm that views infectious disease therapy based on a war metaphor. Microbial pathogens are viewed as the enemy that needs to be eliminated in order to restore health. Increasingly powerful weapons in the form of antibiotics with increased activity and spectrum were felt to be necessary in order to win this war. However, as has been learned through warfare throughout human history, collateral damage to innocent bystanders increases the cost of success on the battlefield. In terms of the human microbiota, the rise of antibiotic resistance, the appearance of opportunistic organisms such as Clostridium difficile and VRE, and an increase in allergic diseases (via the hygiene hypothesis) and autoimmune diseases, such as inflammatory bowel disease, are all thought to be a reflection of such collateral damage.

As we gain an increased understanding of how complex, host-associated microbial communities assemble and maintain structure and function, it is likely that a new paradigm for the prevention and treatment of microbe-associated diseases will arise. In certain cases, the war metaphor will be replaced by a paradigm where management is the key concept. With this new paradigm, the human body can be considered akin to a national park. The management of the ecology of the human microbiota becomes the focus of both prevention and therapeutics. For example, a focus on maintaining beneficial bacteria during targeted antimicrobial therapy of clinical infections could prevent infection with C. difficile or VRE. Conversely, once the host-associated microbiota has been altered to a deleterious community structure (dysbiosis), a therapeutic approach of restoration ecology could be initiated. Approaches using probiotics and prebiotics, rationally designed based on knowledge of the ecology of the community, could fit under this rubric of restoring community balance."

This also says a lot about the recycling of cover material, to inoculate the new feces with beneficial decomposer microbes, the same ones that broke things down in the previous cycle, plus natural selection and evolution with make them more efficient.

As always, please do not hesitate to correct me on any of these points.

Best wishes,
Chris Canaday

Dear All

These pages have been extracted from the Africa Water, Sanitation & Hygiene Vol.8 No.3 which was posted to the forum only last week.

We have been requested by the authors to inform you that you can use any of the photos, provided you cite the source correctly. You can download them in their original size here: www.flickr.com/photos/gtzecosan/sets/72157628912448797/

Thanking you

Mwaniki



++++++++++++
Note by moderator (EvM): Christian Rieck has a few days ago (on 18 June 2013) uploaded an improved version of the technology review. It is still available at the same link here:
www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=874

The improved version has addressed some of the short-comings that were discussed above.

Dear Steven Mwaniki,

first of all thank you for bringing us back “to the roots” – in the review we resumed knowledge about “UDD” solution(s) with the aim to show the possible impact for more holistic sanitation approaches, where we see the UDD-toilets “not instead of”- but “in addition to” other technologies. Certainly the different approaches can be confusing; on one side we have to decide for or against sewer network and centralized or decentralized wastewater treatment plants (WWTP) and on the other side about how to realize fecal sludge transport and treatment and always about disposal or reuse. And in addition there are new technologies, as UDD-Toilets. And yes, UDD solutions have been proven in the last 20 years in many projects worldwide, but until now mainly from a technical and perhaps “cultural” point of view and less from financial and institutional of up scaling. There is a clear lack of proven up scaling projects in UD Technology.

In an holistic approach each solution can has its place and for decision it needs knowledge about the specific conditions (environmental, financial, social, health, institutional... ). In the reality the given conditions often limit the options and on the other hand conditions are changing form one part of the city to the other and have to be respond with different solutions. For instance: One part of the city has water supply and families already invested into water toilets; so, wastewater MUST be treated, sewer could be the only option and the kind of the WWTP depends on local conditions. In another part, families use pit latrines and the most urgent solution could be to organize fecal sludge management. In other parts leachate from Pit Latrines are a risk for public health or people perhaps have nothing that deserve the name sanitary facility (nor water supply) and a UDDT-solutions with adequate treatment could be the only option.

In this case we are still faced with questions as: How to finance or how to stimulate families to invest in own UDD-toilet? What is the adequate treatment? How can this be financed? How can it be controlled? Who has the institutional responsibility? Just to create a base to answer these questions, we resumed in the review the current technical status of UD-twin vault, UD-single vault and UD-VIP and all related treatment necessities. There are still different opinions, as you can see in the forum, but we tried to focus on those with upgrading potential. All decisions in sanitation should be taken on the assumption that all products (onsite or offsite) do not cause harm to health or environment, or at least the related risk must be acceptably low. In an urban context the “acceptable risk” should never be a personal decision, and the argument “still better than a given situation” is not valid for public investments.

In Durban/South Africa the utility for instance decided that onsite disposal of dried faces and urine has acceptable low risk for the whole city to justify public investment in 80.000 private UD-twin vault toilets. Another situation perhaps justifies support for private UD-VIP (more economic, but only possible in mostly dry and rural areas) which also are based on on-site disposal, which means: no public service effort. In El Alto/Bolivia the decision was to support the weekly collection, transport and offsite treatment of feces and urine from 1.000 single vault UD, but not (or only partly) the private UDD Toilet. At last but not least: mobile UDD solutions often aim to finance the toilet and the treatment service by selling the treated products, which is not working until now, as I know, but nevertheless it is an important vision.

Finally, lack of sanitation is primarily due to a lack of public responsibility, awareness and planning, and less (or not anymore) due to the lack of technical options, and not even necessarily due to the lack of financial resources or possibilities to get financing. Therefore upgrading projects must involve the institutional responsibility, and this is perhaps the biggest challenge with which we are facing now.

Heike

Dear All

In his Forward, Mr. Conrad Thombansen mentions that the 'Technology' is intended for the developing and the countries in transition. So, could this point be emphasized that this 'Technology...' is applicable worldwide?

And in thermodynamics, we learnt that 'matter and energy can be transformed, and energy can be converted from one form to another but the total of the equivalent amounts of both must always remain constant’. So, with all the advantages of UDDTs, we still have to deal with the problem of collection,transportation and storage of the faecal material in urban areas especially in Africa where resources are scarce.Could point be revisited?

On wastewater there are interesting reports such as FAO Water Reports # 35 (The wealth of waste - it talks of economics of wastewater use in agriculture) quote.
And IWA also had a Technology review on wastewater treatment in 2011.

These reports support wastewater reuse. Is it a mistake especially for the developing countries to continue entertaining this as an evolution? How do we convince these countries to desist from investing in large wastewater treatment plants and go for the UDDTs?

Kind regards

Mwaniki

Dear Elisabeth (and everyone),

Thank you for looking at all of my numbered points (but also please have a look at the lettered points, in response to Heike, when you have a moment).

My intent is not that my options be stated in the Review as the best or only way to proceed, just that they be included in the list of viable options. In our desire to break Modern Society's status quo of water-based sanitation, I suggest we not make a new iron-clad status quo for UDDTs. Instead, I think it is better to say “Design options A and B work well and there are thousands of successful units in use in C and D conditions. Design options E and F are newer, but are promising especially for conditions G y H.”

We should acknowledge that, although the UDDTs we currently build are very functional, there are things to be improved upon if we want to reach a broader audience.

(1) I still see no justification for saying that the “biosolids” from interchangeable containers are less safe than those of two-chambered UDDTs, unless the containers are impermeable and sealed, such that humidity cannot get out (in which case, I would agree that they would be inferior).

The photo you attached of the basket with liquids coming out is clearly a problem. What would have happened if the builders had saved a considerable amount of expense (and environmental impact) and had simply not put the cement floor in that chamber? I imagine that the presumably dry African soils would have absorbed these excess liquids before anyone even knew they existed. To solve the problem now, I would suggest putting cut-off plastic jugs under these baskets to catch the leachate, without the basket sitting all the way down in, to keep the solids dry. Optimally the basket would fit snugly into the mouth of the plastic bin, so that smells cannot easily come out, and the liquids could be dumped into a soak pit when the basket is changed. By the way, the chamber is so large that many containers could be stored right there, maybe pushed into place with a stick and then pulled out with a hook on the same stick. This would also be a good case for woven sacks, placed in the basket when in use, then stored tied shut and marked with the date.

In new units like the one you showed, if it is preferred to have a cement floor, this could slope slightly toward the center and drain to a soak pit. Also, since this is almost certainly urine leaching out, more education is needed so that the students use the UDDTs correctly.

Thank you, Elke and Markus, for your comments concerning the benefits of interchangeable containers (forum.susana.org/forum/categories/34-uri...stion-on-squat-plate). Please feel free to write that novel, Markus, and post it here.

(2) About using compost as cover material, this could also be compost from kitchen scraps (although fecal compost would arguably be better microbiologically) or fertile soil (sifted and dried), plus it could be mixed with sawdust, rice hulls or other more conventional cover materials and still inoculate the feces with beneficial microbes and help to control odors.

Of course, we have to be careful about all the potential diseases, but the current system in Developing Countries of directly dumping into rivers or open defecation is a recipe for spreading disease. We should remember that all the worst microbial diseases, like diarrhea, cholera and typhoid, die in less than 2 months in the conditions found in a UDDT and we aim for over 6 months or a year to also wipe out helminth eggs, which are the most resistant of our pathogens but are also not so life-threatening (Esrey et al. 1998. Ecological Sanitation; and why was that table taken out of the revised edition?). The scientist who did most of that research, Sir Richard Feachem, is still a professor at the University of California San Francisco (profiles.ucsf.edu/richard.feachem) and could be interviewed about the current state of knowledge on this (even though he does not respond very well to emails).

Furthermore, if we are aiming at scaling up UDDTs, this is a big solution to avoid having to constantly transport material to and from the city, in who knows what vehicle, with who knows how much petroleum. Also, where could we get enough wood ash or sawdust to supply the UDDTs of a big city, whereas, if the soil city-dwellers produce themselves does the job, the problem is solved. In addition, it is feasible to add cover material mechanically, without having to touch it with our hands.

(3) Elisabeth, you stated on this forum (1Mar13) that the Review says that the dried feces from a UDDT should never be considered pathogen-free, although it may not be stated exactly this way in the Review itself. Here is an excerpt of your post (with my underlining and emoticons) :

“What makes this technology review unique compared to other documents which speak about UDDTs:
1. I think we really explained well that a UDDT will not, never, get "complete" pathogen kill and one should not expect that from a UDDT.
2. A UDDT can but does not have to be operated in conjunction with reuse. Even without reuse, a UDDT can be a very good toilet with plenty of benefits compared to other toilet types.
3. The differences between single vault and double vault UDDTs, their pros and cons.
4. Explanations on UDDTs with containers inside the vaults and without.
5. It is extremely comprehensive, covering all design and O&M aspects in different contexts.
6. It contains a good section on costs - something with other publications about UDDTs often gloss over or omit completely.”

A lot of discussion has centered around the study in El Salvador that showed that users of 2-chambered UDDTs that used their compost in agriculture had more helminths (www.watersanitationhygiene.org/Reference...al%20Medecine%29.pdf). However, in reading the details, they were not even trying to apply any certain minimum detention time, but instead the feces were only stored "weeks to months and then emptied" (page 1822, first paragraph), presumably whenever the other chamber filled. Any system can go wrong, if not used right.

This whole discussion (and mystery ) of when or if treated feces can be considered safe rides on the fact that the diseases we are most worried about (e.g., cholera, diarrhea, typhoid, etc.) cannot easily be tested for in these “biosolids”. On the other hand, I believe there is an ample consensus that Ascaris eggs are the most resistant of all the fecal pathogens, so testing for these should give us sufficient peace of mind, since they can be seen conclusively under the microscope. (I also think that the methods for testing for Ascaris eggs can be refined and made more efficient, forum.susana.org/forum/categories/17-fer...xt?limit=12&start=12)

I suggest more testing be done of Ascaris egg die-off over time under different conditions of cover materials (sawdust, rice hulls, soil, ash, recycled cover material, mixtures, etc.), treatments (solarization, thermophilic composting, earthworms, Black Soldier Fly larvae, etc.), and in the different climates of the world.

In any case, we should realize that, if we have a mindset that “once feces, always feces”, that would mean we are gradually converting the entire planet into feces, which hopefully is not entirely true.

Instead of worrying about the theoretical persistence of some microbial pathogen, we should first focus on the very real threat of fresh feces going straight into the environment, as it does today in much of the world. If someone actually gets sick while following our guidelines, we can revise them.

Rephrasing President Franklin D. Roosevelt, let me assert my firm belief that what we most have to fear, is fear itself.

We do not have a publication about the Ascaris study we did. It was part of the project of a student intern. I could potentially copy the relevant part and circulate it. Other confirmations of the absence of Ascaris eggs after 6 months were done independently in private laboratories in the cities of Puyo and Cuenca, here in Ecuador. I would be happy to send samples to anyone in the world who would like to analyze them.

(4) Thanks for contacting Sanergy about the Fresh Life UDDTs … and to them for their informative response.

(5) I think we could call this inertia.

(6) I do think it is worth stating clearly that this is a batch system, in which we have distinct collections of feces that are treated as units, as opposed to a continuous system, like the Clivus Multrum.

(7) I am glad you agree. One could potentially level the pile via the small door for digging out the biosolids, except that the pile often reaches above the bottom of this door … and this door is sometimes sealed with clay or something similar.

(Eight) Yes, there are many small errors in English that add up to the document not appearing very polished, even though it is not horrible.

Here is a sample. The Review says: “The toilet also includes a sub-structure that houses the necessary components for the collection and storage of excreta, so called faeces vaults.”
The use of “so called” indicates that this name is used, but is not correct. The text is generally too long, in my opinion, and I would suggest dropping this final clause. If one were to keep it, the term would be “faecal vaults”, to use the adjective. Also, the word excreta is being used incorrectly. Excreta is defined as “Waste matter, such as sweat, urine, or feces, discharged from the body” (www.thefreedictionary.com/excreta), whereas I believe we are referring here only to feces (or faeces in the British spelling which you seem to prefer). One could also drop “the necessary components for”. Why use the confusing term of "sub-structure" instead of just saying "underneath" or "in the lower part"?

I would be glad to help with such a revision of the text, if you want.

On p. 2, the Spanish word is Baño, with that hat on the n. I, personally, prefer not to use this term, as the UDDT is generally not a place for bathing. I call it “Inodoro Ecológico Seco con Separación de la Orina”.

I have no trouble calling the openings on the backs of UDDTs “small doors”. Other words, such as hatch, would be unnecessarily confusing for non-native English speakers, especially if we think of flies hatching out inside the hatch. Thank you, Tony, for confirming that it is correct to use the word “door” (Post #4215)

(9, new) The Review mentions several times the promotion of UDDTs in developing and transitional countries. I agree that this is where it is most urgent, but the UDDT is a great improvement on water-based toilets, especially in terms of environmental sustainability and public health, which should be promoted everywhere, not just where people are so poor that they cannot afford anything else.

As always, if any of these points need to clarified or corrected, please do not hesitate to tell me.

Best wishes,
Chris Canaday

Elisabeth,

With regards to the use of the term ‘vault access doors’, I believe this is the most accurate, appropriate, and common term to describe that particular UDDT hardware component, though other terms are also acceptable. I have provided a complete justification below.

The Oxford English Dictionary defines a ‘door’ as:

“A movable barrier of wood or other material, consisting either of one piece, or of several pieces framed together, usually turning on hinges or sliding in a groove, and serving to close or open a passage into a building, room, etc.”

A few things of note about this definition: 1) It is framed to be broadly applied, encompassing a number of different materials and opening-closing mechanisms; 2) It is used to describe a removable barrier to a building, room, etc.; and 3) There is nothing inherent to the definition regarding size, whom, or what is intended to pass through the entry.

When I reviewed the Tech Review, the word seemed appropriate and, therefore, I did not put much thought into the semantics. After evaluating this definition, I am confident that this is a good word choice to describe this particular UDDT component.

However, if you have reason to believe that the word ‘door’ is causing confusion for the readers, it could easily be changed to another word that is, at least, comparably descriptive. Elisabeth, you have suggested ‘vault access hatches’ and ‘vault opening covers’.

The word ‘hatch’ is primarily applied in nautical and aeronautical settings, and describes ‘…a square or oblong opening in the deck, by which cargo is lowered into the hold’ (marine) and ‘…an opening or door in an aeroplane or space capsule’ (aeronautics) (source: OED). Though there appears to be a few antiquated definitions that treat a ‘hatch’ as a cover to a small access port in, for example, a furnace, most modern usage defines a ‘hatch’ as the opening itself, rather than the cover. Therefore, the word ‘hatch’ is not appropriate here.

The term ‘vault opening covers’ appears to demand less scrutiny. All words in this phrase are well understood in the English-speaking world and are unlikely to be a source of confusion. One clear advantage of this term is universality: it effectively describes all hinged doors, as well as those covers that are plastered or cemented in place. ‘Vault access covers’ could be used synonymously.

I think there may be some value is establishing consistent terminology for different UDDT hardware components across different organizations and publications. A cursory review of literature found that the ‘vault doors’ and ‘chamber doors’ appear to be the most common terminology, and are used by Stockholm Environment Institute, Netherlands Waste Partnership, WaterAid, Japanese Association for Drainage and Environment, eawag, and many others.

In summary, ‘vault access doors’ is accurate, appropriate, and appears to be commonly used. If you receive feedback from readers that find this term confusing, ‘vault access covers’ would be just as accurate and appropriate, but would deviate from the bulk of literature on the subject.

Hi Elke,

Thanks for these photos.

Is anything done to the inside of the cut steel oil drum to keep it from rusting? I have thought of applying a thin layer of a liquid solution of standard Portland cement (maybe with a mix of latex or resin, as used with paint).

This half barrel would be water-tight (as many prefer), but a layer of dry straw, leaves or finished compost could be added before use, to absorb excess liquids, if this is a problem.

It would seem that a half barrel would have to be changed before it is half full, so as to not be too heavy. Several round poles could also be placed under it, for it to roll on.

(My responses to Elisabeth's comments are coming soon.)

Best wishes,
Chris Canaday

Dear Chris,

I really value very much the time and effort you have taken (in several rounds) to review this document. Thanks a lot! So just to add to what my co-authors Heike and Christian have said, I also want to respond one by one to the comments you made above on 15 March:

You said:

1. In the previous round of editing, we achieved the inclusion of single-chambered UDDTs with interchangeable containers, together on equal footing with two-chambered UDDTs. The current draft, however, states many times that the process of using interchangeable containers produces inferior, less-sanitized compost, without apparently giving any justification for this.

Yes this is true. We struggled for a long time with this issue, how single vault UDDTs and double vault UDDTs can be described side by side in one document. At first we had even removed the single vault UDDTs, as you know. Finally we wrote it like this, where we think it is a "fair" description of the pros and cons of both options. In most cases, I would say that the single vault UDDTs achieve a product that is less well treated than in double vault UDDTs - which does not have to be a problem; depends on the objectives and what you do with it afterwards. Your case might be the only case that is an exception (with the sacks), but in our view it is not sufficiently proven with independent research or that it is in fact achieveable on the large scale with thousands of users. We tried to learn mainly from the large-scale examples which exist, mainly the eThekwini case (Durban) with the 75,000 UDDTs as well as Bolivia (El Alto, www.susana.org/lang-en/case-studies?view...eitem&type=2&id=1583) and Peru (Rotaria).

You said:

I obviously disagree with the following point in Section 4.7 (page 18): “The containers should be watertight to prevent leachate resulting from misuse or diarrhoea from leaking into or even out of the vault. If porous materials such as sacks or woven baskets are used for faeces collection, a watertight receptacle should be placed underneath to catch possible leachate.” The amount of leachate is minimal (unless there is gross misuse) and, if the floor of the chamber is simply soil, it can just soak in, thus avoiding anaerobic conditions and the corresponding smell.

I am a bit undecided here. I can see your point and perhaps the wording should be made less firm here. But how about this photo - check the urine leaking through the basket onto the floor of the vault (I took this photo last year in Kampala; this is the design with woven baskets which was promoted by the Austrian Ecosan Club):

Faeces basket in vault. Vault door missing (stolen). Note urine on the ground. by Sustainable sanitation , on Flickr

You said:

(Has anyone else noticed that new UDDTs have a greater risk of problems with smell, as compared to UDDTs that have been used for years?)

I haven't noticed this. Could it be because novice users simply make more mistakes and therefore there is more odour? And if the toilet has been going for years then it is a sign that the users know what they are doing and thus there is less odour?

You said:

2. Section 6.2 states on page 25 that “There is some anecdotal evidence suggesting that the use of compost as cover material may adsorb odours very efficiently.” I recommend strengthening this in the following way:
“Finished compost is an excellent cover material that efficiently absorbs odours. [...] Canaday uses and promotes the use of finished, pathogen-free faecal compost as cover material, to inoculate the new faeces with beneficial, decomposer microbes and to more sustainably reduce the transport of materials to and from each toilet or neighborhood (forum.susana.org/forum/categories/34-uri...er-material-in-uddts). This will be more acceptable to the average user with mechanisms that add the cover material mechanically, thus avoiding contact with the user (e.g., www.susana.org/images/documents/07-cap-d...n-terris-ecuador.pdf).”

Again, I see your point. I think we should probably at least add a link to one of your publications as a footnote, so that if someone is interested they can find out more about your work (your paper from the SSP journal is already included in the reference list). I think our hesitation to recommend compost as a cover material is that we felt the users are anyway unlikely to have access to high-quality compost (in most cases; your case may be an exception). And if they use lower-quality compost with their bare hands when they grab a fist full from a bucket (even with a scoop), they could end up with pathogens on their hands. An average user has no way of knowing if a compost is "finished and safe" or not (yet), i.e. whether it still contains Ascaris eggs or not. So could be a little risky.

3. I do not agree with the statement that compost from UDDTs should never be considered pathogen-free.

I don't think we said that anywhere, did we? Where? What we did say is "Regardless of the on-site storage ducation, containerised faeces from single vault UDDTs must be post-treated prior to disposal or reuse" (Section 4.5.3).

We don't consider the material coming out of UDDTs as "compost".
We felt that for large scale applications it is important to rather be safe than sorry. Hence, our rather "conservative" approach here. Imagine the court cases when someone gets sick from UDDT use and they blame it on the recommendations made by engineers or scientists who were overly confident with their UDDT designs...

You said:

In a brief study we did of our compost, here in the Amazon, no Ascaris eggs were found beyond 4 months of detention, and independent trials confirmed that 6-month-old compost was free of Ascaris eggs. This may be due to the greater biodiversity of soil organisms found here or the better conditions for composting inside woven sacks (see 1, above).

Interesting. Do you have a publication from this that you could share? (taking into account the difficulties in enumerating Ascaris eggs, like we discussed elswhere on the forum here: forum.susana.org/forum/categories/17-fer...s-in-a-reuse-context)

You said:

4. Sanergy's “Fresh Life” UDDT seems very practical and well thought-out. Thank you for adding this to the text. How did they make such a strong but lightweight and hygienic plastic floor?

I have sent an e-mail to Laura Kraft from Sanergy for explanation. Her answer is now here on the forum: forum.susana.org/forum/categories/52-mob...posting-updates#4157

You said:

5. At the risk of starting a polemic, I would like to state a preference for saying “two-chambered UDDT”, instead of “double vault UDDT”. “Double” makes it sound like it is twice as big (“double whiskey”, “double bed”, “double room”; would a double pole vault be with two poles or two jumps?), but not necessarily that it has 2 chambers.

I see your point. But the word "double vault" UDDT is so wide spread now, that I don't really feel like promoting "two vault" instead... And I agree that "chamber" is probably better to understand than "vault" for non-native English speakers. But again, maybe too late to change that now, as it is more commonly used in all the literature on UDDTs.

You said:

6. I recommend clarifying, early on, that this is a batch system and not a continuous system (as in the Clivus Multrum).

Really? The word "batch" might not appear often, but we often use the word "alternating" which is the same thing, isn't it? If not, where exactly do you think it should be added and how? Is it really important?

You said:

7. Section 8.3.1. states among Daily and Regular Tasks “Checking the volume of faeces in the dehydration vaults and levelling the pile when necessary”. This is an important point in the use of two-chambered UDDTs, which deserves more development in the text, since the feces tend to form a mound under the drop hole. This levelling might optimally be done with a stick that is kept in the chamber itself (to avoid fecal contamination elsewhere) and can be reached and used via the drop hole, but how can the same stick continue to fit as the chamber fills?

Good point. We can make some changes/additions there I think. I would have thought that the levelling takes places via the vault access hatches rather than via the drop hole?

You said:

8. The text could be improved considerably with further proofreading for English grammar and style. I would be glad to help with this, if you like.

I have been reading through it again, after a break of some months, and yes, I have also been finding small errors here and there. But not that much. Did you really find lots of sentences with poor use of the English language?

One question that occurred to me today in this context: We have used the term "vault access doors". Is the word "door" in English rather for something that is big where people can walk through or also for such small doors? I am wondering if the better term might be either "vault access hatches" or "vault access covers" or even "vault opening covers". Or is "doors" OK in this context? I mean something like this:

Doors of faeces chambers by Sustainable sanitation , on Flickr

Is this really a "door"?

By the way, here you see all the photos that are used in the technology review on UDDTs:
www.flickr.com/photos/gtzecosan/sets/721...797/with/5811897698/

And I agree with you that it is an important and useful document. According to the SuSanA library stastics, it is very popular already: Views: 2262 • Downloads: 502. I am so proud of Christian (Rieck), the principal author, for having produced this document!
Let me give the link again in case someone has missed it:
www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=874

Kind regards,
Elisabeth

Dear Heike, Chris and Elisabeth,

I am only now finding the time to review your interesting discussions. Heike's last post has clarified the open points quite clearly, especially the different user perspectives (the faecal waste managers (us ) and the average users ). As I do not have the enourmous first hand experience as Heike and Chris I have nothing to add here.

The purpose of the technology review publication was to give a neutral view on the state of the art of UDDTs. I think we have captured most of the issues to a quite detailed level, but certainly not for all circumstances e.g. for very humid climates as Chris is referring to. So if there are relevant new additions to make I welcome everybody to send your prosposals (text passages) to This email address is being protected from spambots. You need JavaScript enabled to view it..

Thanks Heike for making the case of upscaling! I also find it important to now think in line of upscaling appropriate sanitation solutions as our pioneers do in South Africa. May it be UDDTs or other dry or wet sanitation systems. Our GIZ colleagues in Kenya are e.g. in the process of incentivising water utitlities to introduce UDDTs in secondary towns www.ubsup.go.ke/. This is all not a challenge of technology but more of O&M management and sufficient financing mechanisms.

Cheers
Christian

Dear Heike and everyone,

Thank you for responding, but please have another look at my questions. I did not only mention the use of sacks (and this option was already included in the Review).

Here are some further responses:

A) I suggest that this Review be as inclusive as possible, mentioning many different design and management options that help to adapt to different climatic, budgetary, cultural and sociological situations.

I recommend we refrain from writing things off as “disgusting” (especially if one has not actually tried the option in question), taking into account that many members of the general public may consider the very concept of UDDTs as disgusting, as seen through the lens of conventional thought. The other side of the “disgusting” coin is the humility to deal with our bodily waste, rather than dumping it into the environment. Changing our babies' diapers may seem disgusting at first, but we do it, and changing woven sacks really is not disgusting at all, since the newest feces are already covered and we only need to touch the clean lip of the sack that was folded over the perforated plastic bin that holds it open.

C) The most disgusting thing is for a UDDT to have smell and flies. This is what we had after we built our two-chambered UDDTs here at our ethnobotanical park in the Amazon, likely in large part due to the high humidity, the great diversity of flies, and the rapid turnover of tourists and volunteers who do not always follow the instructions. So I started using the sacks to have a more orderly, dry and aerated column of feces, in which they all get covered better, and, whenever there is a problem with smell or flies, the sack can simply be changed and the problem is resolved immediately. When flies start to emerge from a large chamber, there is almost nothing one can do to stop them, since they continue to crawl out. (One could put traps, but it is better for them to simply not be there.)

D) Interchangeable receptacles are especially convenient for tourism installations, since empty ones can be placed before new tourists arrive, so they need not worry about who has been there with what disease. It is essentially the same amount of material to be moved, we just do so bit by bit, instead of the massive job of emptying out a whole chamber all at once.

E) If we are aiming at longer detention times (as you say), almost nothing could be better than the woven sacks that I buy at the local bakery for US $0.14 each, as full sacks can be stored as long as desired, while more are bought and filled. (Also these sacks are so ubiquitous that used ones are often available for free.) On the other hand, the chambers of a two-chambered UDDT may get filled too quickly (for example, due to a party or a public event) and the air-tight, water-tight buckets that you would prefer may cost $5 each.

F) Another advantage of using sacks is that they take up nearly no space when empty. Many of the units we have built are in jungle villages only accessible by small planes, so the weight and bulk of materials is very limited. In the last couple of years, we have built 37 for use with sacks among the indigenous Achuar Nation, together with 15 two-chambered units, to see which they like better (and because some of the planners could not imagine them changing the sacks) and some of the two-chambered units are now operated by the Achuar with sacks.

G) None of the factors you mention impede humidity getting out of, or oxygen getting into, woven sacks, especially over the course of 6 or more months. For example, when storing grains under high-CO2, low-oxygen conditions, simple woven sacks cannot be used, but instead containers made from sheets of PVC or similar plastic, nearly 1 mm thick, and then there is still measurable movement of oxygen and humidity through these sheets (Jonfia-Essien, W. et al. 2010. Hermetic Storage: a novel approach to the protection of cocoa beans. African Crop Science Journal 18:59-68. www.ajol.info/index.php/acsj/article/view/65797/53504)

H) In terms of dehydration, we store the sacks on sticks laid on the ground, under a building that protects them from the rain, so humidity can exit in all directions and not just upward (as in two-chambered UDDTs).

I) Why would you worry about cleaning the sack, if it has been stored long enough for pathogens to die and it will just be receiving new feces and cover material again? Any remaining compost would help to absorb liquids and inoculate the new feces with beneficial, decomposer microbes (see previous point #2).

J) I would like to reiterate the question at the end of my previous point #1: Has anyone else noticed that new UDDTs have a greater risk of problems with smell, as compared to UDDTs that have been used for years?

I will try to post a video of our system with the sacks, including the changing of them, which is really not terrible. If anyone wants samples of finished compost, I would be glad to send them. Investigators are welcome. More info on inodoroseco.blogspot.com.

Sorry for such a long message, but this is an important document we should all be able to refer to, once it is polished. If I am wrong on any of these points, I invite corrections.

Best wishes,
Chris Canaday