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

  • 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?

Dear all,

This thread about possible sanitation options for peri-/urban areas in African towns is getting longer and longer. For new-comers (and contributors) to have an overview about findings so far, I have compiled a summary of those options which have been discussed so far in more detail:

1 Pour-flush twin-pit vermi-composting (PFTPVC)
2 UDDT
3 Twin pit VIP (DVIP)
4 Double vault vermi-composting (DVVC)

These are not yet all possible options which I can imagine. And although we strive for solutions which use little or no water, and for solutions which close the loop and recover human excreta as resources for agriculture, we have to accept that also other options are sometimes wanted and sometimes even more applicable.

I expect that we will also have to discuss a bit about WC connected to septic tank and soak-away and WC connected to sewer and central WWTP. I will shortly raise these topics and want to discuss with you how service chains of those systems may look becoming as much sustainable as possible.

I attach the overview of above 4 options as PDF file to shorten this post, but if you feel it necessary I can also post the overview, please let me know.

Please let me know where I have recorded something wrongly or where something is missing!

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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  • muench
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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 doing up this summary of the posts in this thread so far. Very useful!

I am now a little bit confused though what you're trying to achieve in this thread. When I go to the very first post in the thread, it was simply a listing of pros and cons of UDDTs, and then a comparison with pour flush toilets with vermi-composting.

However the title of the thread is rather ambitious, being: "which are sustainable sanitation technologies and systems for peri-urban areas in Africa?"
Are we now listing all possible technologies and looking at their pros and cons? Are you replicating or expanding or updating a little bit the Eawag Compendium? ( ecompendium.sswm.info/ ) ;-)

I would say it is a bit hard to have a generalised debate; it's probably easier when we're discussing this for a specific case (perhaps make it specific to the Moshi case?)

Then I am also not sure if you want to broaden it to also consider shared sanitation systems at a community level or several households taken together?
How about those novel container-based sanitation systems (like those of SOIL in Haiti), should they also be included in the menu of options here?

This occurred to me while reading in another thread about pour flush toilets in Africa which has now included discussions on the Indian Sulabh system (with biogas production), see here:

Are pour flush toilets a good idea for (South) Africa?
forum.susana.org/forum/categories/141-ot...dea-for-south-africa

There could be a bit of overlap with your thread in that thread.

Kind regards,
Elisabeth

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  • 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?

Dear Elisabeth,

I thought the thread is clear: I try to compare UDDT with pour flush with ???, i.e. with any other (on-site) sanitation system which may be applicable in peri-urban areas of Africa.

Yes, I want us to discuss pros and cons of the selected systems and I try to build on the EAWAG Compendium, although most EAWAG systems get a bit modified: I prefer the double ‘vault’ UDDT with containers because it is easier for the service provider to empty the ‘vault’. Users who will use the dried faeces in their garden can of course omit the containers. The pour-flush twin-pit system is modified with vermi-composting.

If you prefer, we can restrict the discussion to Moshi or Tanzania if that helps. I want to develop a ‘catalogue’ of options which can be applied in peri-urban areas of Moshi (and Tanzania).

At the moment I want to restrict the discussion to household latrines. Community and shared latrines are not so liked in Tanzania. You find ‘public’ toilets in markets and bus-stops but not so many ‘community toilets’ (as in Ghana). On a plot several ‘households’ may share one toilet but these are then mainly 1-person households of ‘week-end travelers’ who come from the surrounding rural areas of Moshi.

The container-based system by SOIL promotes small containers which are collected weekly and contain still fresh faeces which are taken by the SOIL service provider to a central composting plant. As recommended by Chris P. and Peter A., I prefer to use larger containers (60-90 L) to extend the emptying cycle and reduce transport costs. But eventually we will have to do an economical calculation to establish the better solution. But basically, yes, container-based system are considered (see type 2, UDDT).

Different from the thread you quote, we do not question whether ‘pour-flush toilets are a good idea’ for Tanzania. In Moshi 35% of the households have already pour-flush toilets. What is lacking is the safe service chain (containment, emptying, transport, treatment, disposal/reuse).

And the same aspect seems to me questionable in the thread of the SA sample. They show and say that the receiving pit can be emptied by vacuum truck. I wonder how? Is it lined? Does it use lot of water? In the EAWAG Compendium the pour-flush twin pit system produces dry humus after 2 years of resting. And I have discussed with Dean how we can keep the pit as dry as possible, but moist to ensure the survival of the worms to extend the emptying cycle to 5 years through vermi-composting and also gain better compost.

I find it surprising that SA went to Asia to ‘find’ the pour-flush toilet. They seem to be very common in East Africa (Zambia, Kenya, and Tanzania) as also other posts indicate.

Interesting in the ‘SA thread’ are the discussion by Geoffroy on N-pollution by infiltrating urine and the two papers posted by SudhirPillay on ‘Pollution from On-Site Dry Sanitation Systems’ (127 pages !!) and ‘Characterisation of on-site sanitation material and products in pour-flush toilets’.

Thus, there is a bit overlap between the ‘SA thread on pour-flush’ and our thread but not too much, rather new information and also our thread covers more sanitation options not only pour-flush.

Thanks for your questions and hints,
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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  • Arther1957
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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?

To start with I was wrong, the pour flush the toilet would probably work better in your area. I believe that with 30 inches of yearly rain the environment would be consistently moist appears you have very dry summers (please correct me if I'm wrong about this). As to separating anything out to protect the worms it is unnecessary, they are not only they are semi aquatic they thrive in the muck in lake bottoms. Although they must have oxygen available when they come to the surface. They are used in septic systems in parts of England and British Columbia the only difficulties I could foresee with simply taking your present model and dropping some worms and bedding perhaps some loose paper or leaves to get them started is the temperature they thrive at temperatures between 55 and 80°F they can survive over 100 but they're not of much use to the process because they're not moving or eating. Mind you this is the temperature inside the box. I have to admit I don't understand some of the things that are said here, I will learn! I personally build a toilet using cement or stone or even baked sheets of clay held together by more clay. I don't generally use plastic because it creates an environmental hazard, plastic breaks down into microscopic particles and has a half-life of 30 million years I grant its convenient and cheap. I also admit that I do not have the education most of you do. I spends a couple of months a year building toilets in the Yucatan. And the rest of the time studying because there's a lot I don't know! And you are all professionals, it just occurs to me that there might be a simpler way than dealing with plastic and the refuse from it. If the plastic is simply for a warm sanctuary they need none. If it serves some other purpose that I have failed to understand, perhaps a natural product like clay or cement can be used in its place. Although this would increase the cost initially it would not have to be replaced for a very long time, a cement septic will last 50 to 100 years, baked clay much longer but only in dry climates. To reuse you only need to remove the finished fertilizer dump a few of the worms back into the empty toilet and drop something for them to eat in until somebody comes to feed them. I therefore urge you to use a long-term solution and hope the short-term is not necessary. Also it only takes six months to a year after the system is closed for the worms consume everything so you might consider checking it frequently after the system is not in use.
I hope you will consider some of the suggestions, and informed me as to any mistakes I might have made concerning design environment or my understanding of your particular situation.
Many thanks
Kevin Cleveland
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  • goeco
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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 Elisabeth/Hajo,
I would suggest that the problem here is that there is a disconnect between the susana forum and the susana wiki. Susana appear to be resourced to manage content, but beyond what you (Elisabeth) are doing I don't see anything happening. The susana wiki should progress knowledge by condensing what the forum users contribute. Us forum users donate our time into advancing knowledge but unless the knowledge is condensed into a regularly updated wiki, the threads get lost in the big ball of wool. In this case Hajo has put a lot of effort into updating our knowledge via this topic because he has recognised that the current published best practice is actually behind the state of the art. Until somebody sorts out the susana wiki into a useable resource and then someone is resourced to monitor the forum and update the wiki (with reference to the forum), then going forward neither will be useful to practitioners. Practitioners don't want to troll through tedious forum posts to locate a gem of knowledge. Congrats Hajo on producing your document, your conclusions are good, but unless integrated into a functional wiki they'll be lost.

A Forum progresses knowledge through discussion and interaction.
A Wiki records and updates changes in knowledge and the history of such changes.

They each have a separate role in content management but to both be truly valuable require a level of integration.

cheers
Dean

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  • goeco
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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 Kevin,

The discussion to this point has been around composting worms (tiger worms, red worms), which do not survive in muck. We have been talking about a fecal composter designed for composting worms. You are talking about something different (tubifex worms). I have no experience with tubifex worms but if it were as easy as you say I would have thought someone would have thrown some down every pit latrine in Africa with some leaves and solved the worlds problems by now! Maybe nobody has thought of it?

cheers
Dean

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  • Arther1957
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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?

in reality they cost maintenance keeping it reasonably wet in a dry climate, and the only thing they really do is speed up the decomposition process. Although I have been told that the fertilizer after warm digestion is better than just decomposed fecal matter I don't know. I think the major reason that they're not used commonly is the same reason a few years ago nobody ever heard Of Black Soldier Flies.. They're kind of off the beaten path. I personally think they're great, but I am neither well-educated nor particularly smart which most people on this site are.
Sincerely Kevin Cleveland
by the way I assumed since the subject was turning fecal matter into fertilizer that "Sewer Worms" were the worms we were discussing. Sorry for missing the point
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  • 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?

Hi Dean, Elisabeth,

Yes, I agree that with this discussion we try to find advanced solutions beyond current ‘best practice’ in which we seem to be a bit successful (larger containers as on the Otji toilet, vermi-composting on the ‘UDDT’ and on the pour-flush).

And so far I thought by having the discussion ‘in public’ on the forum, it is sufficient to let everybody participate. But you are right, nobody wants to read through pages and pages on the forum to learn what has been ‘newly’ developed and what is the current, latest status.

But before putting it on the WIKI, we need professional discussions, comments by competent practitioners and professionals. At least I feel the results not yet ‘competent’ enough to put them on WIKI. How do you see it?

And then, who has the time to put them on WiKi? I have glanced at the ‘admin’ of the sanitation project, will take me ages to understand.. :ohmy:

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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  • muench
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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 Dean,

You talk about Wikis but not everyone will know what you mean (actually even I am not sure). Do you mean the SuSanA Wiki pages (e.g. see here: www.susana.org/en/susana-wiki?site=Main%20Page ) or do you mean Wikipedia?

We have discussed here on the forum about the pros and cons of SuSanA Wiki pages and of Wikipedia pages: forum.susana.org/forum/categories/198-wi...ference-between-them

Personally, I think a critical mass of authors is key and I focus my time on Wikipedia. But SuSanA Wiki pages have the advantages of more "freedom", as Wikipedia is quite tightly regulated. So to get working in there could also be worthwhile but might require paid editors.

By the way, I saw that you recently got your first Wikipedia article online, on vermifilters:
en.wikipedia.org/wiki/Vermifilter
Well done! Please do a separate announcement on this when you're ready?

I agree with you that Wiki(pedia) pages would be a great way to make information that has been gathered through forum threads more easily accessible. So I agree in principle with your suggestions in that respect.

However, for what Hajo wants, such Wiki pages would not be sufficient because each of them would describe a technology in isolation but he wants a comparison for a particular case.

Hajo, I think this only works if you have a very particular case in mind, because we cannot generalise what's better, it all depends. So if we take the case of your city, Moshi, have you already described somewhere in this thread what the characteristics of that part of Moshi are which you want to provide with sanitation? If not, could you please summarise it, as that's a key piece of information.

I guess this is the job of a good consultant: you take all the available options and you shortlist them for a particular case and then perhaps come up with the top 3 options. These top 3 options are then costed in detail and put up for discussion amongst the stakeholders. (We haven't yet talked that much about costs in this thread.)

Anyhow, I just think it's important to stress that perhaps the title of this thread is misleading ("which are sustainable sanitation technologies and systems for peri-urban areas in Africa?"), maybe better is "what is the most sustainable sanitation system for peri-urban areas of Moshi, Tanzania and areas with similar characteristics?")

Regards,
Elisabeth

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  • rochelleholm
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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?

As part of the ‘catalogue’ of options which can be applied in peri-urban areas of Moshi (and Tanzania), please consider an improved transitional pit latrine targeted for peri-urban areas which was developed just south of you. Please consider a road trip to visit us in Mzuzu and see us.

Chidya, R. C. G., Holm, R. H., Tembo, M., Cole, B., Workneh, P. and Kanyama, J. Testing methods for new pit latrine designs in rural and peri-urban areas of Malawi where conventional testing is difficult to employ. Environmental Science Water Research & Technology, 2016, 2, pages 726–732. DOI: 10.1039/c5ew00246j pubs.rsc.org/en/content/articlelanding/2...w00246j#!divAbstract

Good luck with your project!

Rochelle Holm, Ph.D., PMP
Mzuzu University
Centre of Excellence in Water and Sanitation
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  • 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?

Dear Elisabeth, dear Dean,

I had a look at the previous thread on ‘difference between SuSanA Wiki pages (AkvoPedia) and Wikipedia’ and I tend to agree that Wikipedia may be the preferred target where (important/relevant) findings of our thread may be recorded for the general public. Especially since the ‘WikiProject Sanitation’ helps to find relevant sanitation information more easily. And Dean has ‘voted’ for it already by putting ‘vermifilter’ online on Wikipedia and I found it also inserted in the WikiProject.
Congrats, Dean!

On the contents and intentions of this thread: yes, I am looking for solutions applicable in Moshi, but I want to keep the discussion as general as possible so that as many as possible readers feel attracted and can benefit from it.

Restrictions which I want to make for the discussion are:

• we talk about peri-urban areas where plots are too small to allow digging new pit latrines when necessary,
• plots are too small for reuse of humanure on the plot,
• or where users refuse to handle humanure themselves,
• which all results in the requirement for a professional emptying and collection service for most of the users of whatever the on-site system produces.

Otherwise we have all sorts of conditions in Moshi which ask for one or prohibit the other option of sanitation system (as in other towns in Tanzania or in Africa):

• we have a sewer system (58 km) in the centre of town where we have to strive to connect as many as possible to make the system sustainable;
• affluent households in the low density areas have septic tanks with soak-aways;
• less affluent have pour-/flush toilets connected straight to the soak-away (which I use now to call a ‘soak-pit’);
• and about 30% of the households have still pit latrines;
• the planned area of Moshi has an extensive water network with 20,000 house/plot connections (serving about 46,000 households);
• while in unplanned areas (of the municipal area) people depend on water kiosks or wells;
• we have areas with rocky underground, with impermeable underground and with high water tables as well as areas which are conducive for infiltration of sanitation effluent;
• we have areas which cannot be connected to the sewer/central WWTP due to geographic restrictions, eventually they could be served by de-centralised systems (sewer and DEWATS).

By starting this thread, I want to discuss which are the pros and cons of different options – even of innovative ones like vermi-composting - in the peri-/urban context considering technique, environmental conditions, service chains and finances (investment and O&M).

Thus, we do here on the forum what ‘a good consultant does’ (‘take all the available options’) and we will then discuss with Moshi stakeholders (utility, municipality, users) which are the most appropriate solutions in which part of the town considering the different aspects and ‘come up with the top 3 options’. Therefore I question whether we have to change the name of the thread, or?

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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  • 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?

Dear Rochelle,

Thank you for your posting and advice on your work in Malawi.

In the page for which you provided the link, I can only find an abstract. Is it possible to get the full report so that we can understand better what an ‘improved transitional pit latrine’ is?

As you may have seen on this thread (page 3, #18675), I am very skeptical about the application of pit latrines in the peri-/urban context and therefore would like to hear from you whether in the frame of your research work you could develop an emptying technique for pit latrines which can deal with the extreme conditions in latrine pits (dry, wet, solid waste, collapsing pits) and which could be the first step in a sustainable service chain (empty, transport, treat, reuse/dispose FS).

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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