This may help out for your main question. For others, see second attachment.

- Sudhir


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Note by moderator (EvM):
If you're reading this post without being logged in: The first attachment is also in the SuSanA library here: www.susana.org/en/resources/library/details/385

Buckley, C., Foxon, K., Hawksworth, D., Archer, C., Pillay, S., Appleton, C., Smith, M., Rodda, N. (2008). Research into UD/VIDP (Urine Diversion Ventilated Improved Double Pit) toilets, prevalence and die-off of ascaris ova in urine diversion waste. Report to the Water Research Commission by the Pollution Research Group, University of KwaZulu-Natal, South Africa

The second attachment is here in the library:
www.susana.org/en/resources/library/details/1245

Buckley, C., Foxon, K., Rodda, N., Brouckaert, C., Mantovanelli, S., Mnguni, M. (2008). Research into UD/VIDP (Urine Diversion Ventilated Improved Double Pit) Toilets: Physical and health-related characteristics of UD/VIDP vault contents - WRC Report No. 1629/1/08. Water Research Commission, South Africa

It isn't so hard to roughly work out of there is enough oxygen in a confined space to enable aerobic decomposition. Given additional complexity of the movement of air through semi-fluid and partially dehydrated faeces, I think it is a pretty reasonable guess that only the surfaces of material in a vault will be composting. As Clint says, to be reasonably sure that the material is actually composting one would likely need to find a way to force air through the collection chamber and/or agitate the contents.

A UDDT which is not properly dehydrating nor with enough air for composting must be the worst of all possible conditions.

You mention that you are using vaults to TRY to compost without any incorporation for oxygen to be able to COMPOST. From my experience, from Alaska, where it is frozen, to Central America, where it is humid, composting utilizing tanks, which have designs for oxygen to circulate, not only dehydrate the RESOURCES more than adequately, but utilizing vermiculture the end result in a very short period of time is soil and liquid usable fertilizers for non-edible crops.

If you are truly trying to compost you need tanks/vault with adequate ventilation. Our tanks have a suspended perforated false floor bottom for the oxygen to circulate and for the liquids to drip into the excess liquid removal sump and then be pumped into a separate liquid tank for use as a liquid soil amendment. This helps in keeping the composting material moist instead of septic.

I again try to emphasize that human excreta and urine are RESOURCES and not WASTES and if treated as Mother Nature intended, composting, you will recover valuable RESOURCES instead of assuming that ALL animal/human resources are harmful.

Clint

Yes - moisture is the main factor we've been encountering. Ambient moisture, ground moisture, and moisture in the toilet material when the UD mechanism does not work to specification. For example, the OTJI system (that works well in arid environments) produced a fecal slurry in the units observed in Haiti. The material did not dehydrate. The communities were afraid to touch the vaults out of fear of contracting cholera. The toilets were foul and covered with maggots. Over 60 gallons of wet waste needed to be removed from 155 households. It was a hazardous material job and we know the Haitian company dumped it illegally.

In Nicaragua, we were impressed by how dry the vault contents were in the better built units, however all of the "compost" material sampled tested dirty. With the single vault designs the vaults fill and need servicing before the proper storage time is achieved to destroy/reduce pathogens. It most cases, 12 months was not adequate to safely treat the excreta. I'm not sure how any measurement of PH can be achieved in the field or how this can be a practical or even cost-effective monitoring protocol.

Hi all,
It is interesting, so many points coming in. In similar lines, thought of bringing in the following point as well related to “moisture” which seems would be very relevant when we consider practical realities.
This could also be looked at as - one aspect that I would also desire in the criteria such as that of the compendium is the “moisture” content - in addition to the pH, temperature and duration that the WASH practitioners could use in the design, monitoring and evaluation of UDDTs.
In principle, UDDTs are supposed to operate through dehydration and raising of the pH and temp. But in practices where there may be excess moisture (because of misuse or faulty design or construction of the toilets) then the process that would take place in the vaults should tend to be composting (please correct me if this should be otherwise) rather than dehydration which would mean apparently need of a longer retention period (was wondering how this would be different from the pit toilets processes) than one suggested for UDDT [such as that suggested as follows in the Compendium of Sanitation Systems and Technologies - “Faeces that are dried and kept at between 2 and 20 °C should be stored for 1.5 to 2 years before being used at the household or regional level. At higher temperatures (i.e., >20 °C average), storage over 1 year is recommended to inactivate Ascaris eggs. A shorter storage time of 6 months is required if the faeces have a pH above 9.”].
This apparently seem to be demanding for a – measure of dryness to be included in the criteria for UDDT (and how it could be measured/assessed best on site and at the users’ level); and a need to look at the whole process as a continuum ranging from dehydration to composting.

Thank you Chris!

I have been curious about the bag storage method and was planning to try some experiments utilizing this technique. This may be a better solution to composting in some situations because of the space, labor and other inputs (carbon material and transportation) required to collect and treat the material. After a complete cost analysis, our partners realized that re-use of the vault material will be cost prohibitive if high heat composting is the only treatment option available.

Overall, I find these discussions interesting because it's unrealistic to test the safety status of dehydrated and stored feces-material in the field. Yet these toilets are still considered the gold standard. In my opinion, the only real advantage of the UDDT toilet is passive management. However, in the failed schemes we've documented, passive management is just that — and the projects fail because of it.

We have observed many kinds of UDDT designs in Nicaragua and Haiti - ranging from crude cement structures with no ventilation to very nice, expensive designs with exceptionally well functioning toilet seats and UD mechanisms (some costing over US$1,000). We also have extensive experience with a large failed project involving the OTJI toilet design in Haiti (over 300 toilets were installed in one community and abandoned in six months).

We have found that many people like the improved designs over pit latrines, and they tend to keep the toilets very clean at first — until the vaults start to fill up. We've also found that many households are sharing units with two or more families, so the vaults fill much faster than estimated - especially when people add ash, dirt and lime to control odors.

Most of the toilets are single vault units, so these designs present specific management challenges. Perhaps the double-vault design is the only way to ensure adequate storage and drying time in more humid environments.

Recently, the government of Nicaragua installed single-vault toilets in low-lying coastal communities with no vault hatch or mechanism to remove the contents. We're not sure what they were thinking, or how these toilets are supposed to work. We've been told that the toilets are abandoned within a year of installation. For this reason, the local authorities have a bad impression of EcoSan-- one official told me there were too many "toilet graveyards" in the area. People will continue to build flush toilets that lead to faulty and poorly built septic systems or pipe into open sewers.

One international NGO is piloting 1-liter flush toilets in the region but these units cost over $1500 and can only be purchased through a micro-credit program. Clearly this price point is out of reach for the majority of the population, but I think many organizations won't explore EcoSan solutions because there aren't many successful projects to draw inspiration from. It seems that many of the UDDT toilet designs tried in the country do not perform to specification, and the material in the vaults is too difficult to manage — thus the projects have very poor outcomes.

Even when working in high-density peri-urban environments where there is potential demand or need for "compost" and other soil amendments, NGOs need to figure out who is going to manage and ultimately use the end-products from these toilets. Only a small segment of rural households can optimize use of a UDDT. In other situations, we find that market linkages need to be developed - thus safety and quality standards for this material will likely need to be more rigorous. EcoSan project cycles need to be a lot longer in duration and more holistic in scope than a narrow focus on trying to improve toilet coverage. Otherwise they just contribute to more environmental and water pollution if people are forced to dispose of the material themselves in canals, streams and ditches.

Case study data and questions about testing aside, we do wonder if it's possible to generalize about the advantages of specific designs over others, or if the "software" and cultural issues are really the most important. We also question if some designs should be avoided completely unless climatic conditions are ideal. There is value in low-tech solutions and training but sadly most donors only want quick fixes.

Thank you!

Alisa Keesey,
Program Director, EcoSan Consultants INT/GiveLove

Dear Alisa,

Thanks for bringing this to our attention. It is always good to learn from our mistakes and try to correct them, so as to advance more solidly. In this case, it seems the hardware was installed without the software.

Are these Two-chambered UDDTs? Can you post photos please? Are they all the same? Do any ever get flooded or absorb significant moisture from the soil?

As I have mentioned on this Forum, I consider the best use of dried and decomposed feces is to recycle them in the same UDDTs as cover material for the new feces.
forum.susana.org/forum/categories/34-uri...terial-in-uddts#2866

It is now 5 years that I have been doing this at the semi-public UDDTs in the Omaere Ethnobotanical Park I help to coordinate in the Amazonian part of Ecuador. We constantly have new users and we explain how a UDDT works and about the cover material recycling. When they smell that there is no odor and see that it looks like any other fertile soil, they quickly get over any squeemishness over this concept.

For extra peace of mind, we store the feces for over a year in permeable, polypropylene sacks that allow water vapor out and oxygen in. When we open the sack, we find a beautiful, rich soil that anyone would want for their garden.

I do not have quantitative, publishable data, but I am certain that in the first few years, there were fewer odors and flies with each advancing cycle, plus the material was increasingly crumbly and presentable. I attribute this to a natural selection of microbes and fungi that are more and more efficient at breaking down exactly that which is in the feces.

If the ex-feces from these Nicaraguan UDDTs are not safe yet, due to improper management, they could receive secondary treatment, such as pasteurization in solar ovens (Sanivation style), drying thinly spread out in the sun, additional storage, or thermophilic composting.

Education of the users is obviously key, and I would be glad to help write or proofread Spanish-language instructions for them, if you like.

Best wishes,
Chris Canaday

Note by moderator (EvM): the next few posts were originally in this thread dealing with parameters for testing health and safety status of UDDTs but have now been moved into this new thread.

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I'm working in Nicaragua on several EcoSan projects. On the Atlantic Coast there are hundreds of abandoned vault toilets, and even more being installed regularly by NGOs and the government. We've been contacted by several local organizations to help communities manage these toilets and figure out a way touse the toilet contents.

As discussed here, there is a huge misconception about these toilets because people frequently call any dry toilet a composting toilet - and refer to the semi-processed toilet material as compost.

This year we opened 85 vaults and found a very wide range of variation with the toilet material. This makes it quite challenging to standardize a management plan for the communities. In some cases so much lime was added to the matrix (to control odor) it was almost cement-like. When we talked to the households participating in the project, we learned that they were given no training on how to manage the toilets, or how to empty the vaults. They had absolutely no idea what to do with the vault contents.

We carried out the vault contents in sacks and started a pilot project offsite to treat it by thermophilic composting. Next time we will use horse or donkey power to haul the loads. We activated the semi-processed material with market waste and dry cover material. We hope to share our results next year. Due to the high population density in the barrios, we observed that there was not enough space to trench the material safely - and these particular communities were not engaging in small-scale farming, so they have no use for the material. The urine is piped into the ground.

We are now trying to do a pilot study on secondary composting using different bin designs and matrix composition. Compared to our efforts composting in dry tropical zones, the Nicaraguan coast is challenging because of the high rainfall and the lack of dry cover material. While many people in the WASH community are quick to brush off humanure composting, we have observed hundreds if not thousands of failed vault toilet schemes. We are very interested in connecting with researchers who are looking at secondary treatment approaches at various scales.

Vault toilets make household management easier on some level but we still believe that in many situations the reuse of this material is very problematic. The NGOs that we work with planned to harvest this material and use it in bio-intensive farming projects but the test results from the UDDT Toilet pilot showed that all of the contents tested dirty.

We are just starting some small collaborations with similar projects in Chennai and Assam India. Without lab testing and other testing equipment to use on-site, this work is extremely difficult. However we feel that this is a hugely neglected area of study.

Alisa Keesey
Program Director GIVELOVE Humanure Composting & EcoSan Training Program