Moving forward with this discussion, please see link to pour flush toilet video from Partners in Development:



The toilet was modified to have low flushing cistern and was piloted in South African schools. The lessons learnt are available on Susana to download:

www.susana.org/lang-en/library/library?v...eitem&type=2&id=2000

Let me start by wishing everyone a great 2013 and beyond.

In my experience in South Asia there is a strong preference of pour-flush over dry toilets. My feeling is that this has something to do with a very strongly held concept that water has a purifying and (ritually) cleansing effect. For this reason the "wet ecosan" or urine diverting twin pit (UDTP) toilet has been developed in Nepal. This is a traditional twin pit(or Sulabh) toilet with a urine diverting squatting pan.

In Nepal this toilet is readily excepted and appears to be more popular then the UDDT, however in communities where insufficient water for even a pour flush is available (year round!) it is much more difficult to sustain operation.

I have not worked in an African context, but would suggest the following thought process to be included in a discussion on which toilets are more suitable:

1.) Is there enough water available for year round operation of a minimal flush toilet option (squatting or pedestal, based on local preference)? This is not purely yes/no but more on a scale of 1 to 5.

2.) How strong is the "cultural" preference for a water based solution?

After asking these 2 questions I think the community and the project can come to a conclusion about what is best by balancing the wish for flushing (which often exists) against the possible added burden of having to get more water for the household.

Off course other factors, like soil condition, also play a role and should also be discussed.

In short, deciding on which toilet has the best chance of sustained use is likely to be influenced by very local factors and therefore we should start with an open mind and help the community decide between the options available.

Kind regards

Marijn Zandee

Dear Geoffroy,
Thanks for the understanding:
1) I am glad that you understood –and share - the point why urine diversion is not the first issue in these cases.

2) I think it is totally right to question the pollution aspect. We have always to think about this aspect and we have to question us again and again. And difficult situations do not justify hazardous contamination – and it is clear that the word hazardous describes a subjective view.

For me again the eThekwini people are getting it right.

[/ul]When there is no possibility for individual toilets – communal blocks

When there is room for individual toilets (without sewer) – UDDT

Now they are thinking about a collection service for the UDDT for feces and if there is commercial value, as well for urine. They consider the feces (potentially) hazardous (when not well buried) and the urine a potential revenue source (in future).

Christoph

Okay , i will formaly like to introduce my self to the forum.
My Name is Masilu Rocky Malebogo ,stay in South Afrca in Pretoria,in working in a sunitation instutution as a project manager for sunitation project around africa at large.
MY appology for bagging in to the forum without introduction.

Hi Sjoerdnienhuys

My understanding is that the sanitation system used in Zambia in the '60s was the Aqua Privy, a kind of latrine directly above the septic tank which did not use a P-trap of gooseneck type seal. At least I have seen drawings of this kind of design attributed to Zambia, and I have also seen a few in the field here in SA. What I do not like about that design is that if the pit is not water tight then the water seal is lost and then odours and insects become a problem.

Rocky

There may well still be places in SA where water is very scarce, but in my experience in KwaZulu Natal that is not the case. We are after all the country that came up with the concept of 6000 litres free water per month.

DEAR ALL

THE IDEA OF POUR FLUSH TOILETS TO ME IT SOUNDS LIKE WE WANT TO BRING BACK WATER IN THE TOILETS , I HAVE A STRONG BELIEVE THAT A WATERLESS TOILET WILL BE THE BEST SOLUTION AT THE CURRENT MOMENT , LIKE IN SA WATER PROBLEM IS LONGER AN ISSUE BUT A MATTER OF LIFE AND DEATH, PEOPLE GLORIFY A HALF GLASS OF WATER SO IT WILL BE VERY MUCH IMPOSSIBLE FOR THE POOR COMMUNITY TO PUT 2L OF WATER IN THE TOILET, ABOUT THE GRAY WATER IT MEANS ONE HAS TO WAIT FOR ONE TO USE WATER TO BE GREY BEFORE HE/SHE CAN GO TO TOILET, WHAT ABOUT IF I HAVE A RUNING STOMACH IT MEANS I WILL HAVE TO COMPROMISE CLEAN WATER IF I DO NOT HAVE GREY WATER.
GOOD PEOPLE WATER IS LIFE WE TRY TO SAVE EVERY SINGLE DROP OF IT.LETS TRY TO SOLUTION WERE WE WILL ONLY USE AND HAVE DRY PIT IN A WATERLESS TOILET.

ROCKY


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Note by moderator (EvM) to Rocky: Please do not use all capital letters in your post as it looks like you are shouting! Also please still follow my request to introduce yourself, even if it is only a brief introduction. Thanks

Dear Christoph,

Thank you very much for sharing your working situation...I feel sorry to focus on environmental aspect while it is probably unappropriate. I appologize to be out of the theme and hope the collection will work. Thanks again for sharing.

Geoffroy

Dear Geoffrey,

these 2 pictures might give you an idea.





We are working in the peri-urban area of Lima, 10 mm of rain“fall“ per year, absolutely no green… so nothing to fertilize. Rocky area, no groundwater at all (I´m not trying to defend the contamination with N, it might be a real problem in some areas with very shallow bore holes, but even in these cases UDDT are still better as they do not cause a coliform contamination).

The bathrooms (see next 2 picture) we implemented two years ago are in very good shape, the double chambers have been cleaned several times.





In this surrounding even the burrying of the treated material is not easy. We build in this area about 80 bathrooms and currently we are analyzing how a collection service could be put in place. The problem are the low household numbers, 80 households is just not enough to set up a service model for collection every 6-8 months.
Yours
Christoph


P.S. in one picture you might see the toilet bowl of the installation they had before. They used to pour some water after some uses, just used water, as they do have the water by cistern trucks. This is an example of “wealthier” people as they had a toilet bowl.

Dear Christoph,

thank you to make me remember that more essential issues than environmental one still have to be solved.
I have no data on N loss in septic tank. As N is introduced in form of N-org and NH4+, denitrification would not occur (denitrification needs NO3- which needs O2); the main process would be hydrolysis transforming N-org in NH4+. losses could mainly occur in form of NH3 volatilisation if pH is high, but wastewater pH is usualy around 6-6,5; so N loss would be low.

In N pollution perspective, I think the bigger the area of infiltration, the best, and water-based sanitation permit a repartition of effluent to larger area than urine only. But difference could be low.

How could urine/nutrients be re-use in your projects? Is there no fertilizer demand?

Yours,

Geoffroy

Hi Geoffroy,

Just a quick answer. Your calculation of N load... does it not apply in the same way for infiltration after a septic tank? It is exactly the same Nitrogen load.

My main point in promoting UDDT is not the urine diversion (that might be interesting in future), my point is a good, healthy, clean, odorless solution, much easier to maintain than pits and a permanent installation...a real bathroom. Pourflush toilets offer this possibility as well, so they are equivalent in regard to the user comfort, incomparably better than VIP latrines.

From the pollution point of view in nitrogen the solutions are equal.

Regards.
Christoph

Dear everybody,

I feel like recycling of nutrient is being forgotten, and the groundwater pollution dynamic under-estimated. If urine is diverted, it is mainly for reuse purpose, no? I'm ok to say that soil can be effective barrier to pathogens, but not for N : If we say 3kgN/pers/year in urine, let's say 2kg, it would require about 55m²/pers to meet the max agricultural application of 350kgN/ha/year, wich is the highest limitation in Belgium (from the European Nitrate-Directive of 1991) aimed at limiting N contamination to groundwater. Infiltration is quite different than fertilisation as the deep is often much higher (N is then about nearly not transformed nor consumed). If A family of 4 or 5 pers use UDDT with infiltration of urine in 3m² or less, it would be more than likely to be a pollution; . Ok, it depend on the type of soil, density of household, and the depth of soil + hydrodynamic of the area will determine the time necessary to reach the water table (it can be over 20 years). I don't belive ther is no impact. Where goes the N? Ther might be denitrification, but there is an excess....

Again, I'm quite suprised to read that UDDT toilets are used without urine reuse. If it is the case, it would be advisable to create N-contained in C structure like compost; Any material containing high C/N could be used to fix at least some N on C structure to produce something solid like compost which is easy to stock, has a lower volume and is much less reactive than mineral N.

If there is no reuse, in a N water pollution perspective, I think that it is always beter to increase the area of infiltration : so water-based sanitation would be better in that point, even if the difference migh be very small. But is this conventional or sustainable sanitation?

Poor flush toilet seems to be a good solution in towns/village, where density is high and water usefull for transport, especialy if there are buildings. As far as I know, dry sanitation in building of more than 2 floor is difficult to achieve, and it is difficult to find a Urine-diverting-flush toilet that give good performance and is userfriendly.

Stay the question : How to plan the recycling? if nothing is planed, pollution is created, maybe even more than in conventional systems.

Thank you very much for your reply

With my best greatingS,

Geoffroy

Pour-flush was introduced and became more common in Zambia and other central African countries during the sixties when I worked in urban settlement upgrading. The desire for (pour)flush toilets is largely derived from the luxory and water wasting European full-flush toilet systems; these were connected to septic tanks.
Water shortage is already a problem in many settlements and is not resolved by rainwater collection.
I agree with Christop that pour-flush is only one option and I also would advocate the UDDT when it can be kept oudourless. For farming and forestry development there is an increasing large need for fertilizer and in urban environments (housing settlements with over 100.000 inhabitants) there will be no space/capacity for soil absorbtion of the sewage.
When pour-flush is introduced in urban settlements, it should be linked to biogas systems for generation of cooking gas, pathogen reduction and fertilizer production.
In some areas there may/will be night frost, hence the pour-flush system needs to be kept frost free. In low-income housing that may be not always the case.
Like with most technologies, there is no single technology for everybody. Developers should present the various options with advantages and disadvantages.