CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

  • christina von heyden
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CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear SuSanA,

we are currently in the process of developing a small community based sanitation project in the slum of Kibera, Nairobi. Therefore, we are trying to figure out suitable options for the specific site including pros and cons of different ecological sanitation models as well as costs. I would very much appreciate expertise in this regard.

The site is located on a former swamp area, meaning groundwater is rather high and a connection to a sewage system is not possible. There is a dirt road nearby but the site cannot directly reached by a vehicle. As it is on the edge of Kibera, there is no lack of space.

The toilets will be used by the community as well as by school children, all in all appr. 100-150 people per day.

It seems to me that there are two possible options, one would be UDDTs, the other one might be Biogas / Dewats. Pit latrines or septic tanks do not seem desirable or even possible. As for now, there is no Biogas plant in the area, where the faeces could be brought to and used for energy purposes.

The community is fine with the idea of separating urine and faeces, also with using urine as fertilizer. There is a rather small agricultural business on the site where urine could be used for that. There might be more possibilities in the near future. As for now, the UDDTs would probably best designed as an Arborloo as there are not enough business opportunities for the reuse yet, but developing income generating activities with and for the community are high on our and our partner organizations agenda.

As mentioned earlier, I would very much appreciate advice in this regard starting with simple questions like: How is „washing“ best accomplished in UDDTs? How many UDDTS will be needed for 100-150 customers? Does Biogas/ Dewats sound like an option? What are production and maintenance costs for the different models (I have read UDDTs in Kenya cost around 500€ for a two chamber system)? How to handle a high ground water level or floods? What other aspects should we take into consideration? (In case of UDDTs, I am aware of the high need for awareness raising and education). Are there more ideas for a suitable ecological sanitation model fitting to the above mentioned circumstances?

More details on topography, groundwater und sewage system are available.

Thanks for your support!!!

Christina

Christina v. Heyden
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  • Florian
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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Hi Christina,

never easy to give clear advise based on limited knowledge of the situation, so just a few considerations:

As for UDDT with 2 chamber system, they are usually above ground, so no problem with high groundwater table. The chambers should be high enough to be above flood level. If UDDT are the best option depends on the attitude of the people (happy with waterless system that needs high maintenance) and the possibility of reuse.
As for the number of facilities, best is to aim at each household having a toilet rather than providing shared facilities. If shared community facilities are really the only option, then you need to think carefully about a robust maintenance system with clear responsibilities.

Arborloo is maybe not a good option with high GW-table, especially if the groundwater is used for water supply.

You are mentionning sewage, is that for greywater? For greywater systems without or with black-water (in case people want to have flush toilets and have enough water for that), there are various treatment options and combinations(constructed wetlands, differenty types of septic tanks, biogas digesters, etc.) High groundwater tables will cause some difficulties for most of these options, but do not exclude any in principle.

For an overview on technology options, the SANDEC compendium is a good starting point: www.eawag.ch/forschung/sandec/publikatio...ompendium_e/index_EN

In any case, spend as much energy and thoughts on operation, maintenance and financing as you do on technology choice.

Wish you success!
Florian


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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear all,

I agree with Florian's responses, thanks Florian.
First I would go back a step and ask Christina to explain who is "we", i.e. you started your first sentence with "we are currently in the process of developing a small community based sanitation project in the slum of Kibera, Nairobi."?
How is this financed, is it all "donor driven" from the outside or are the users contributing? How is the longer term operation and maintenance going to be financed?
Florian mentioned this as well: this O&M aspect is totally crucial, otherwise your beautiful toilet (whatever technology you choose) will not be beautiful for long...

Are the 100-150 users per day connected in some way to each other (like part of a clos-nit community or even a clan) or could they be anyone, like in a public toilet? Will they have a pay per use scheme or pay a monthly fee or something like that?

Now I need to find out if you already know these publications:
SuSanA case studies from Kenya (most of them co-authored by Christian Rieck who also uses this forum):
www.susana.org/lang-en/case-studies?show...&vbl_0=0&country=113

Do you know the ecosan Kenya blog?
ecosankenya.blogspot.com/

This document will tell you something about costs of UDDTs, it is the GIZ technology review on UDDTs (unfortunately still not yet totally finalised):
www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=874

Which Kenyan institutions are you going to involve and how?

An Arboloo works with a different concept than a UDDT. There is no urine separation in the Arborloo and groundwater pollution can occur (as a pit is used). So probably not suitable for you here.

UDDTs will be cheaper and easier to construct than Biogas systems or DEWATS.
For the later you need flush toilets (is water supply easy or difficult?).

Washing in UDDTs? Use a third hole for anal washwater (see photos here:
www.flickr.com/photos/gtzecosan/sets/72157625967050794/ ) - but the users must be taught that this is important (whereas for flush toilets you need no further education on this). Do you have many washers in your area?

Do you want your system to take care of greywater as well (showers?) or only excreta?

Remember to consider aspects of inclusion for the toilets (please don't build them all with steep stairs! --> people with disabilities).

Now I am curious to hear your further questions and points of clarification.

Regards,
Elisabeth

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  • christian.rieck
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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear Christina,
Florian and Elisabeth have already described some technical options. You can also add the option of lined pit latrines that also allow fairly easy sludge removal (if the pit is made accessible), requires little space and can hardly be misused no matter how much trash or wash water is going into the pits. However they need to be emptied regularily. What is feasible at the end depends very much on the locality (space, groundwater, accessibility) and the willingness to pay for faecal sludge serives.

There are pit emptying services available in Kibera which need to be paid for (by the school or by fees from the users). The disposal of sludge from pit latrines, UDDTs and biogas systems is a huge challenge. Certainly dry faeces from UDDTs are the most easiest t handle. Urine and washwater can be socked away. Currently all almost all the sludge is dumped in rivers and manholes. It will be almost impossible to address this problem with a single small scall problem like your proposed one.

Ecosan is hardly a solution if closeby space for agriculture is missing and assurance of the hygienic quality of fertiliser products is hardly achievable. Other projects like peepoos ( www.peepoople.com ) have however a pretty smart self-sanitising solution that seems promising. They currently work on reuse of the filled bags in tower gardens (soil filled bags) that fit in front of almosst every door step. Or peri-urban farmers who can pick up the bags for agroforesty and flower farms. Get in touch with them for more info.

I would not recommend biogas systems in Kibera as it is complex to operate and maintain, requires kitchen and animal waste to produce sufficient biogas (this waste is rare in slums), water, is expensive and produces a highly polluted waste water which would need treatment. It also needs space which is limited. DEWATS is similar but focuses on cleaning the waste water.

Working in slums ususally requires a strong CBO or NGO that can coordinate and manage tensions and conflicts that definetly arise during such projects. How is the situation in your case?

Cheers
Christian

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  • christina von heyden
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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear Florian, Elisabeth and Christian,

thank you so much for your answers as well as the various links, both of which are of great help.

Let me try to clarify on a few issues and give answers to your questions:

„We“ means the Berlin based Noah Foundation and KDI (Kounkuey Design Initiative), a US/Kenyan initiative/NGO who has been working closely with this specific – and other -communities in Kibera for the last 6 years and will be the project leading organization on the ground.

The target group of the project is an organized community of around 30 people as well as appr. 80 school children. The community expressed the need for toilets and will be responsible for operation and maintenance in the long run. The project will not be 100% donor driven, the community will have to contribute financially (as they have done in former projects with KDI). There will be a pay per use or monthly fee system - which is very common in Kibera - the school children will be able to use the toilets without paying. As the toilets will be in the ownership of the community, shared community facilities are really the only option.

As for now, there is no connection to the sewage system at the site (no greywater, no blackwater), a connection to a freshwater pipeline is being established at the moment. Showers are not high on the agenda yet.
I am not sure if the accessability is suitable for pit latrines (for sludge removal), also – as mentioned above, there is no connection to a blackwater sewage system at this stage. The peepople option is quite visible in Kibera, actually there is a peepoo drop of very close to the site. Nonetheless, this is not the option prefered by this community. People I have talked to about it do not consider it as a very valuable solution as you have to pay for the bags, so many prefer to use normal plastic bags instead (flying toilets).

Actually, the idea of ecosan toilets does sound most appealing to us, it is also being favoured by members of the community who has seen UDDTs in Kibera. As the community will be responsible for O&M in the long run and income generating activities are very important for them in general, the idea is to not only use fertiliser products for the small agricultural business on the site but to also look for a market outside (compost from the garden is already being sold by the community).

The above information given, what do you think? How many UDDTs would be needed for the number of users (100-150)? What are the challenges of assuring hygienic quality of fertiliser products which can actually be used for agriculture? One more detail: People will use tissue to clean themselves inside the cabin.

In case of interest, I am happy to also share documents on topography, groundwater und sewage system (maybe better by email though).

Thanks a lot for your help!

All the best

Christina

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  • christian.rieck
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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear Christina,
Firstly how much monthly fee are you talking about? What services will these payments cater for?

Secondly the hygienic quality of fertiliser products, especially the faecal matter, can hardly be achieved due to heavy contamination with resistant parasites and other pathogens. The dried faeces from the vaults of the Urine diversion dehydration toilets (after at least 6 months storage) are not safe enough for commerical use e.g. for purchase or own use of urban agriculture. Even a secondary treatment via composting is a challenge since you need to follow a strict composting procedure to ensure complete hyginisation. You could however check out the hotbox from Richard Higgans who promises complete hyginisation after 2 weeks. I have not seen research and credible analysis about that yet. Check here www.susana.org/images/documents/04-meeti...ggins-composting.pdf

So I think reuse is in general problematic for large-scale systems other than household systems. Similarly urine get easily contaminate with pathogen via faecal-cross contamination which will affect urine quality and causes need for treatment (storage of 4 weeks).

UDDTs are however also a very good option if you only opt for disposal of urine and faeces. Urine can be infiltrated. And faecal matter buried or taken away by pit emptiers. The emptying of vaults is far easier and much less offensive for the service person - thus also less expensive. Since has been done in large-scale in eThekwini, South Africa. See the SuSanA case study www.susana.org/lang-en/case-studies?view...peitem&type=2&id=791 .

In case you have sufficient space (which I doubt) you can bury the faeces on the same plot of the school. Per year you would have about 10 to 20 cubic meter per year from 150 people (considering 100 kg/person). The pit would need to be around 3x4x1,5 meter big and can be planted on top with fast growing trees. With school children and day school the amount of faecal matter certainly decreases. The Water research commission in South Africa has researched about the faecal sludge burial from pit latrines and found that burial in soil for 2 years caused Ascari-die off which is the main indicator for pathogens. See the presentation from Jay Bhagwan held at the AfricaSan3 conference in Kigali (SuSanA side event) www.susana.org/images/documents/04-meeti...aecal-sludge-mgt.pdf .

I hope to information leads to more informed decision making.

cheers
Christian

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Re: UDDTs, reuse, peepoos CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear Christina,

You said:
"Actually, the idea of ecosan toilets does sound most appealing to us, it is also being favoured by members of the community who has seen UDDTs in Kibera."

Whose UDDTs were they? What were they like, how well are they working? If it works well, can you copy their design? I was not aware that there are UDDTs in Kibera and would like to know more (photos?).

You asked about the number of UDDTs needed for 100-150 users. I would say the same number as if you had any other toilet type. What ratio of toilets to people do you want and what can you afford to build? Maybe 20 people per toilet cubicle, so about 5-7 toilet cubicles?

Are you going to build one block or two blocks (to separate male/female better)? How far will people have to walk to get there? Will they be open 24 hours per day? Will they be safe to use at night? (if not, would people use Peepoo bags during night time perhaps - did you see the other discussion topic on peepoo bags on this forum?)

Whatever you do, please do not build steep stairs which would lead to exclusion of people with disabilities and many elderly people. This is a common issue with UDDTs in my view - even though UDDTs can also be built without stairs if people think about it.
To read more about this issue see our new factsheet on "making sustainable sanitation inclusive for people with disabilities":
www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=1210
One option for UDDTs without stairs are the bench UDDTs.

Also I think Christian painted a picture that is too bleak regarding safe reuse...! I do believe safe reuse can be achieved if the multiple-barrier approach is applied diligently. He said "heavy contamination with resistant parasites and other pathogens" - here he is referring to the helminth eggs (I assume), these are the most persistent pathogens. I don't think you would want to dive into serious external composting her, like the Hot Box system which Christian mentioned. This would be far too much effort to handle for the community, in my view (unless they are totally committed).

Probably shallow burial of the dried faeces is a good method to be safe but to still make the nutrients available for the roots of plants.

In any case, when it comes to reuse, there would have to be a strong driver, i.e. people practising urban agriculture with a need for fertiliser. Is that the case?

But even without reuse, UDDTs still make a lot of sense due to the much reduced odour and safer handling of urine and dried faeces (compared to faecal sludge).

Regards,
Elisabeth

P.S. As the discussion has moved more towards UDDTs, I have moved this topic from miscellaneous systems to UDDTs (in my role as administrator).

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Re: UDDTs, reuse, peepoos CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear all,

sorry for the delay but I will finally try to give answers to some of your questions (and add a few new questions):

Users will have the option to pay per use or buy a monthly unlimited pass. The fee per use will be 3ksh, the monthly pass would be 300ksh per month per family.

There will be a paid caretaker for the toilet who will be paid from the revenue that the toilet generates. The caretaker will operate the toilet (collect $, clean, give paper, soap etc) at all times that the toilet is open (from 6am to 9pm daily), large maintenance items for the toilet will be paid for from the revenue generated and saved in the maintenance account.

To make the toilets accessable for the elderly and people with disabilities, we are considering to build them on an artificial hill. This will also protect from flooding and can meet questions of urban design.

Urban agriculture is being practiced at a small scale at the site. There is space for expanding the agriculture activities but options for disposal should also be available. Unfortunately there does not seem to be a market for selling urine or dried feces in Kibera or Nairobi at this point.

It would be important to know if the dried faeces can also be buried if the water level is high (danger of contaminating the ground water?)

Basically, the toilet blocks + urinals will be build for school children and community group members which add together to about 150 users per day. Of course other residents living in the zone where the site is located might also be willing to use them, which might then sum up to 500 - 1000 users per day. There are other toilet blocks in the wider zone so these would not be the only option. Still, the number of possible users remains vague at this point. Could you give advice on the user capacity per double UDDT to keep them working sustainably? Do you think 20 cubicles will be sufficient?

Finally Elisabeth, the UDDTs the community visited were not located in Kibera but close to Nairobi airport.

Thanks for your support!

Best wishes
Christina

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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

(note by moderator: I have merged your 4 posts into one; please don't post 4 times, rather put it into 1; also please introduce yourself with 2-3 sentences)

What they found was that Kenya’s poor were interested in having compact stalls that could fit into the tight spaces of their usually one-room homes, rather than large community outhouses. They wanted a “permanent” feel to the stalls rather than the flimsy feel of a porta-potty.



Auerbach and Vallabhaneni knew what they didn’t know. What they didn’t know was that they couldn’t draft up a sanitation solution in Boston – without the insights and input of those in the developing world. Committed to launching a start-up that would truly work for the poor, the two, along with a team of MIT classmates traveled to Kenya for the answers.




Sanergy team that includes engineers, architects and designers drew up plans for a 3×5 toilet made out of thin shell cement that is locally produced for $200 per unit. Each toilet is designed for a 100 uses per day. They are units, which also collect waste in double-sealed 30L containers, rather than pits, or septic tanks “that are then drained into waterways.” It is this waste collection that is key.


Sanergy produces toilets that are franchised to local operators who charge around $0.06 per use. Currently the company has two toilets serving approximately 150 each day. One is at Bridge International school (a for-profit school supported by the Omidyar Network), the other in Kibera, Kenya’s largest slum.



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Re: CBS in Kibera, Kenya: UDDTs? Biogas/Dewats?

Dear Christine,

Both biogas and UDDT toiltes are already built in Kibera and being used by Umande Trust, local NGO who now have over 50 biogas toilets in slums in Nairobi. Kibera itself has 19 biogas toilets that are owned by community or school. Umande Trust also constructed UDDT in a school in Kibera.

I would suggest that you go to Umande Trust website or contact them This email address is being protected from spambots. You need JavaScript enabled to view it.
for more information.

If you are in Kenya or have opportunity to visit, you may want to visit one of those biogas latrines, average 200-500 people use those latrines.

with regards, hiroko
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