UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Hi Hajo/Elisabeth,

to clarify, my views are that the Susana wiki should be the central point of knowledge on advances in sanitation, i.e. recording the "cutting edge". Wikipedia requires more substantial references than consensus reached here in this forum by experts, whereas our own wiki would reference the forum.

A wiki can be a very simple thing, it's just an information resource that multiple users contribute to, with the history of changes tracked. This forum is part of the Susana website - as unfortunately is the Akvo wiki. Nobody uses the wiki though, the downfall being the controlling third parties ideas on how a wiki should be managed, resulting in an impossibly complicated mess nicely described here .

Elisabeth, thanks for letting me know my article on Vermifilters/vermicomposting digesters was published on Wikipedia. I tried to contribute a page on vermicomposting digesters to the Susana-Akvo Wiki nearly a year ago... I think my page is languishing in an Akvo sandbox somewhere and has never seen the light of day.

Unless as users we can integrate our knowledge gained from the forum into the wiki then we're essentially wasting our time here because a forum is to discuss ideas, not to record conclusions.

Regarding comparisons, these can be dealt with in a wiki because pages are cross-referenced. You have the individual pages on each technology/method which can include the different contexts, but also have pages comparing the different technology/methods under a specific context. The context could be peri-urban areas in general, and this could be expanded to peri-urban areas with specific conditions. Of course under each technology/method's page the appropriate operational contexts would be listed. The wiki just needs to be set up right.

cheers
Dean

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Dear all, dear Rochelle,

I have downloaded and studied the research paper which you quoted in your posting, drawing our attention to ‘(a corbelled pit latrine targeted for rural areas and) an improved transitional pit latrine targeted for peri-urban areas’ and developed in Malawi.

The paper is mainly about the development of testing methods for materials (and workmanship) used in the construction of these two pit latrine types by local masons in Malawi and where conventional, internationally standardised tests are not possible due to lack of resources. The tests refer to testing of the soil, the mud mortar and the concrete (or better cement mortar as it lacks aggregates).

But I do not want to discuss the appropriateness of the tests for other countries or other types of toilet structures but rather question the fundamental need of having such tests for pit latrines in peri-urban areas which according to the paper are supposed to be emptied (while the corbelled pit latrine for rural areas is not to be emptied)!

My opinion is that we should not promote pit latrines in peri-/urban areas because they are not designed to be emptied. So, why develop solutions for problems of a sanitation technology which is the least developed and users rather would like to see them replaced with something more developed than being ‘improved’?

Therefore I am asking us:

Why designing substructures which do not collapse when the pit is emptied or exposed to heavy rains?

Why developing appropriate local testing methods for local materials and workmanship?

Why designing technologies for the emptying of latrine pits which are only accessible through the squat hole and contain sludge from fluid to muddy state and all sorts of solid waste from gum boots to bones which all cannot be handled by a single device?

Why developing regulations for the protection of the pit emptiers through protective clothing and safe procedures?

Why design and construct conveyance systems for FS which mostly has to be transported in drums?

Why have to develop alternative treatment works when the FS from latrine pits cannot be fed into standard waste water ponds?

We have plenty of threads on this forum where solutions for above problems are being developed, tested and discussed but I don’t see that we find lasting solutions.

I agree that we have thousands of pit latrines in African towns and it will take considerable time to replace them with something more appropriate and sustainable. But in the meantime no more toilets with such inappropriate properties should be promoted and constructed.

Only temporary measures should be taken to protect the population as good as possible from the health hazards of existing pit latrines while more sustainable solutions are developed and implemented.

Ciao
Hajo

We can't solve problems by using the same kind of thinking we used when we created them.
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Everything should be made as simple as possible, but not simpler. :-)
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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Right on Hajo!!

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

It all depends on whether you think that we should start from where people are or from where we would like them to be. Whatever we 'experts' think, many people in peri-urban areas do use some form of pit latrine, in most cases financing and paying for the latrine themselves. There are many issues with this - I would favour efforts to promote low-volume pour-flush rather than direct drop pit latrines for instance, because of the problems with removing extraneous waste dumped in the direct drop latrines. But, the reality is that people do build rather crude on-site sanitation facilities regardless of what official rules and regulations say and there is an argument for intervening to at least ensure that such facilities are as good as possible. In Indonesia, for instance, something like 90% of urban sanitation is on-site and the vast majority of on-site facilities are 'cubluks' - fairly basic pour-flush to leach pit systems. It may be appropriate to suggest alternatives to such systems, particularly where the water table is high and people use groundwater for drinking, but people are aware of the dangers and say that they use drinking water from other sources. If we ignore what people are doing themselves, we run the risk of being completely irrelevant, at least in the short to medium term.

Valid points can be made on both sides of the argument so it will be interesting to hear what others think - preferably on the basis of field experience rather than speculation.

I am looking forward to responses

Kevin

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Dear Kevin,

Thanks for your posting, I am always happy seeing ‘new faces’ on this thread.

I fully agree that we cannot ignore what ‘people are doing themselves’, how they judge their doing, what they want, what ‘official rules and regulations say’, and what the attitude is towards sanitation in general and towards specific solutions in particular.

But I think ‘people’ may not always know about alternatives, what is possible and what is affordable. They may have pit latrines and dream of having a flush toilet (with sewer connection) as we have in Europe and USA. They don’t know about sustainable solutions in between and their politicians and administrators (who have all flush toilets at home and in the office) support their believe that there are only sewers because they don’t want their country being deprived of the development ‘by the flush’.

And I am quite certain that it is an (almost) unrealisable dream to provide a majority of urban population in Africa with sewer connections even in a long run. eThekwini in Durban did the cost estimate for a comprehensive sewer system and concluded to provide the peri-urban population with UDDTs (now about 80,000 Nos) and the respective service chain.

During our city-wide sanitation survey in Moshi, we learned that more than 30% of the households have pour-flush toilets connected to a big ‘soak-pit’. They omitted the septic tank in order to save construction costs and O&M costs for regular emptying of the septic tank and feed the black- and grey-water straight into what was supposed to be the soak-away for effluent from the septic tank only. Now the soak-away becomes a ‘soak-pit’ with the same problems as a latrine pit: it cannot be emptied properly because it is not accessible or the sludge is often too dense to be pumped.

That is what ‘people are doing by themselves’. Can we not try to advise them that they should rather build two smaller pits and use them alternatively (2-3 year cycle), so that the FS dries, turns into humus and can be dug out easily when the second pit is also full? The construction costs are not higher for two small pits than for the big ‘soak-pit’ which they build now and the emptying of the small pit every 2-3 years does not cost more than the futile efforts to pump the sludge from the current soak-pits.

Ciao
Hajo

We can't solve problems by using the same kind of thinking we used when we created them.
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Any intelligent fool can make things bigger and more complex... It takes a touch of a genius - and a lot of courage to move in the opposite direction.
E.F. Schumacher
Everything should be made as simple as possible, but not simpler. :-)
Albert Einstein
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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Dear Hajo

Thanks for your quick reply. First of all, I agree entirely that there is plenty of scope for outsiders to engage with people to develop improved sanitation approaches. That is undoubtedly very important and I have been advocating it for most of the 35 years or so that I have been working on development issues. Like you, I don't think that sewerage is the way forward in many urban situations. I think my initial response was prompted by (1) the many times that I see outsiders coming in with bright new ideas and completely ignoring local knowledge and (2) the tendency for governments to specify high standards and particular technologies without any thought of the mechanisms for communicating ideas to the people who are doing the actual construction.

One of the interesting things that comes out of various discussions is that emptying pits in African countries is more difficult that in Asian countries. (That is a very broad generalisation but it does seem that the sludge in African pits is much less liquid than that in Asia, perhaps because less water is being used. I agree entirely that emptying pits is often the weakest link in the sanitation chain.

Turning to double pit and double vault toilets. The idea has been around for a long time (in Africa it goes back at least to a late 1970s World Bank-funded project in Botswana) and is theoretically very attractive. The challenge, which promoters of the system have arguably not looked at enough, is to ensure that it is used as intended. A couple of years ago, I looked at many double pit systems in low-income areas in Bangladesh and not one was being used as intended, despite the fact that they had been built through a UN/DfID-funded project with apparently high levels of community support. In Lusaka, some double vault toilets were built a few years ago but when I visited the area, none were being used as intended. People would go back to the first vault, which had settled to some degree, when the first vault was full. My assessment is that one of the problems in Bangladesh was that it was assumed that people would empty the pits themselves but the reality was that they would get a sweeper to do it and were not that concerned to ensure that the emptying was safe and hygienic. Also, they had limited space and often built over one of the pits, making the system difficult to implement. In Lusaka, I think there was a lack of support but another issue was that more people were using the toilets than assumed in the design, so that they were filling up quickly. Rightly or not, people thought that the contents were still unsafe.

This is not to say that the basic concept is not worth promoting but we need to be very careful to look at how systems work in practice and to learn from the experience,

Overall, I would still argue for a greater focus on improving the systems that are already there. That is not to say that there should not be parallel emphasis on introducing new ideas to tackle the obvious issues with existing technologies. Perhaps the main point to be taken from both our emails is that it is important to start from an assessment of the problems faced in each local situation and to develop responses to those problems. The sanitation options for a crowded settlement like Kibera may be very different from those for low density peri-urban areas on the edge of towns like Maseru and Gabarone.

Kevin

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

dear Kevin,

I think it is not a specific fault with the double pit or double vault toilets in Botswana, Bangladesh and Lusaka that they don't work when not properly used and managed. Even pit latrines, septic tanks and sewer systems elsewhere in the world fail if they are not properly managed.

And for me sanitation management means a sustainable service chain comprising accessible containments, emptying and transport service, treatment and reuse/disposal organised by a responsible service provider. This must be the local utility with support by the local government authority. They can outsource single services but they are responsible to ensure that the service chains work.

ciao
Hajo

We can't solve problems by using the same kind of thinking we used when we created them.
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Everything should be made as simple as possible, but not simpler. :-)
Albert Einstein
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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

My original point was that pit latrines should not be dismissed out of hand - there are peri-urban situations in which they can be appropriate. Leach-pits are used in many parts of Asia, albeit with water seals. If there is room, Peter Morgan's fossa alterna option is possible - I have seen places where people use this principle themselves. It is not so different from the twin-pit idea but perhaps simpler.

There are indeed issues with most sanitation systems and any system is only as good as the systems that are in place to manage it. My point about twin pit systems is that they are not a panacea and careful attention needs to be given to the systems for ensuring that they are used as intended by their designers. On this, I recommend that anyone who is interested should get hold of a copy of Eric Dudley's book 'The Critical Villager: Beyond Community Participation', which is the best book on the way in which technical ideas are transmitted that I know. He suggests that we should always ask ourselves how a technology might fail and also emphasises the need to identify the 'big idea' behind any technology, the knowledge needed to apply that technology and the practices that are essential if the technology is to work. I have applied this framework to sewerage and it can be applied to other types of sanitation. It would be interesting to hear of first hand experience of examples of twin pit or double vault systems that have been used as intended by their designers. (including Sulabh if there are any independent evaluations).

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

dear Kevin,

I fully agree that pit latrines can be appropriate: wherever a full pit can be abandoned and be replaced with a new pit. But they are not appropriate where a SINGLE pit has to be emptied. This is the ultimate criteria and not whether rural or peri-urban.

Wherever there is no space to replace full pits with new pits a double pit/vault system must be considered. This can be Fossa Alterna, double pit VIP, or pour flush with twin pits... any system which allows one pit to dry out over minimum 6, better 12 months before it has to be emptied for reuse...

..and of course they have to come with a service chain for emptying, collection, treatment and reuse/disposal. Septic tanks and sewers are also not left to the users for maintenance but a formal service is provided.

The book sounds interesting, I will search for it.... already ordered :P

ciao
Hajo

We can't solve problems by using the same kind of thinking we used when we created them.
Albert Einstein
Any intelligent fool can make things bigger and more complex... It takes a touch of a genius - and a lot of courage to move in the opposite direction.
E.F. Schumacher
Everything should be made as simple as possible, but not simpler. :-)
Albert Einstein
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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Dear Hajo and all

I think that we have almost exhausted this subject. I would just like to make two points. The first is that it is dangerous to extrapolate from a specific situation and assume that the lessons from that situation apply universally. This is well illustrated by the example of pit latrines (in which category I include pour-flush latrines). The problem with single pits is that of emptying them and it is clear that this can be an important factor in some African cities, where water use is limited so that the pit contents tend to be consolidated and are only removable by hand - clearly a dirty and unhealthy business. On the other hand, as I think I mentioned in one of my earlier contributions, perhaps 80% of sanitation in Indonesia is provided by pour-flush toilets connected to leachpits. The content of these leachpits is fairly fluid and can be removed by vacuum tankers. In fact, many of the pits are large and I came across several instances of pits that had not been emptied for over 40 years. There are potential issues with groundwater contamination but this applies to any on-site systems, including the Indonesian Government's preferred and more expensive option of providing septic tanks linked to soakaways. (The pathogen reduction through a septic tank is not great). This is an example of a situation in which it would seem to be worthwhile to pay more attention to what people are already doing and explore ways of improving their practice.

My second point is that we must always look at institutional arrangements when considering sanitation options. Hajo - you say that for you 'sanitation management means a sustainable service chain comprising accessible containments, emptying and transport service, treatment and reuse/disposal organised by a responsible service provider. This must be the local utility with support by the local government authority. They can outsource single services but they are responsible to ensure that the service chains work'. This is good in an ideal world but unfortunately we do not live in an ideal world and these conditions do not always exist. They did not exist in the Bangladesh example that I gave earlier, despite the involvement of donors and an emphasis on providing support to the community. They are difficult to ensure in other situations. Work that I did in Kenya a few years ago suggested that local government had a theoretical role in approving sanitation initiatives but no specific responsibility for promoting and providing sanitation. I suspect that the same is true in many countries. In Indonesia, there was virtually no local capacity to advise on what constituted good sanitation. My point is that we often have to deal with imperfect institutional contexts and project and programme planners need to recognize this. I believe that many of the failures of past projects can be attributed to a failure to recognize institutional constraints. Recognizing and responding to those constraints makes action much more difficult but it is a necessary condition for success - if there was one point that I would emphasise to people getting started in the field of sanitation, and indeed development in general, it is this one.

Kevin

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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Dear Kevin and all,

if 'the content of these leachpits is fairly fluid and can be removed by vacuum tankers' then I would say, it is not working as a leachpit. Probably due to high ground water level or because the soil is not permeable or has been clogged by solids in the effluent. But I fully agree with you that situations in each country and even in each town have to be analysed individually to find do-able solutions.

Regarding institutional arrangements, I do not expect them to be there and ideal. I am saying that with the development of technical sanitation plans (infrastructure and service chain), also the capacities of public and private stakeholders have to be build to provide and manage these service chains.

This is possibly one aspect forgotten in the past: sanitation development is not only building toilets but also building service chains and the capacities of potential service providers as well as the strength of sanitation governance. A task for at least 10 years... in one town...

ciao
Hajo

We can't solve problems by using the same kind of thinking we used when we created them.
Albert Einstein
Any intelligent fool can make things bigger and more complex... It takes a touch of a genius - and a lot of courage to move in the opposite direction.
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Everything should be made as simple as possible, but not simpler. :-)
Albert Einstein
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Re: UDDT versus Pour Flush (with vermi-composting) versus ???: which are sustainable sanitation technologies and systems for peri-urban areas in Africa?

Good point about the leachpit. I have had a quick look at the results of a survey that was done in several towns in Indonesia. Certainly, both sludge and supernatant water were present where the water table was high. Just under 60% of pits in areas with low water table had water above the sludge. The Indonesian pits only allow percolation from the base and this may reduce the rate of percolation.

The results showed that the average time to the first emptying of the pits was something of the order of 15 years - I would have to look up the exact figures. After that, repeat emptying was often required after another 2-3 years and this does suggest to me that the need to empty came about because the percolation mechanism was failing rather than because the pit had filled with sludge. That is speculation and is not definite but it fits the observed facts. Whatever the exact mechanisms, it does seem that the sludge accumulation rate is low - less than 20 litres per person per year on average - and this has implications for sanitation design. The available figures for Africa are quite variable but I do think that this reflects the much greater risk of bulky materials being dropped into direct drop toilets.

The other point from the Indonesian experience is that vacuum truck operators did not report problems with emptying pits, although it is possible, perhaps probable, that they were not removing the more consolidated material at the bottom of the pit. However, overall the system works reasonably well and puts relatively small demands on government services, which is a plus when those services are not strong.

Kevin

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