Documents for "Design and Technologies" (Decentralised Treatment Facilities for fecal sludge) - UBSUP Programme Kenya

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Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

Dear all,

key documents about the design and technologies of decentralised treatment facilities produced in the context of GIZ's water sector reform programme are available in the SuSanA library:
www.susana.org/en/resources/library/details/2448

The library entry contains the following documents:
  • DTF Design Adaption Manual (pdf) • Size: 3.06 MB
  • DTF Construction Manual (pdf) • Size: 11.26 MB
  • DTF BoQ (xlsx) • Size: 0.22 MB
  • DTF 3D simulation (pdf) • Size: 0.21 MB
  • DTF Structural Drawings of Modules (pdf) • Size: 10.12 MB

Kind regards,

Annkathrin

Sustainable Sanitation Alliance (SuSanA)
Secretariat
Located at Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
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  • alexandra85
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Re: Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

Dear all

After a long period of silence, let me give you a short update on the DTF implementation. First of all, a quick reminder on the general layout, the DTF can treat up to 22m3 and comprises the following modules:
1. The Receiving Bay / Balancing Tank: for screening and flow rate control
2. The Settler tank: for separation liquid and solid (sedimentation of heavy particles and flotation of lighter particle)
3. The Anaerobic Baffled Reactor: for the anaerobic treatment
4. The Vertical Flow Constructed Wetland: as polishing step (filtration, sedimentation, chemical adsorption, aerobic/anaerobic treatment)
5. In addition to the main treatment line, the DTF has 2 sludge drying beds (for the desludging of the settler and the ABR), 1 composting shed, 1 incinerator (to get rid of the screened solid waste) and 1 operator office

You can find the description of each module in the DTF poster:


The UBSUP programme (the description can be found here and the explanative video here is implementing 11 of this DTF. As of today 7 DTF are completed and in operation and the 4 remaining are following closely. The overall implementation was not without challenge, however I believe that thanks to our standardized approach and our strategy to build the capacity of the Water Services Providers (WSP: the main implementer), we managed to achieve a lot (consequently reaching a significant number of beneficiaries) in a limited period of time. All implementing tools (trainings material, technical drawings, BoQ, monitoring tools, etc.) can be found either in the SuSanA library or the WSTF toolkit . With regards to the challenges and lessons learned, here is a non-exhaustive list of what comes to mind off the top of my head:
1. It crucial to convince the institutional stakeholders to accept and adopt on-site and decentralised sanitation options, as they tend to hold a strong belief that conventional sewerage is the only option for sanitation. National up-scaling works best with sector structure as they provide an ideal ground to replicate a concept in different areas.
2. In a context where decentralised treatment facilities are not common, it is important to provide the necessary support to the main actors involved in the DTF construction (technical team of the WSP) to ensure sustainability and quality of the implementation. This support can be quite demanding, but the standardized approach enables to reduce the amount of effort: grouped trainings, same design therefore no need for customisation, same implementing tools available online, etc.
3. Proper appraisal of the amount of faecal sludge to be treated is needed before constructing a DTF. The demand should be enough to justify the investment and operation costs of a DTF. The demand should be calculated by the amount of faecal sludge that can be emptied and transported: collection services activities rather than number of inhabitant or even number toilets. We are currently facing the situation where the DTF is operating way below capacity because there are no vacuum trucks available and because of their design, most of the latrines can’t be emptied.
4. In order to achieve maximum efficiency, it is recommended to focus on the main purpose of a treatment plant, which is to guarantee safe treatment and disposal of the waste water and faecal sludge. The topic of reuse and recycling is very trendy nowadays (biogas, fertiliser, briquettes, etc.) and might look very attractive from an external point of view, however it can easily divert the attention from the real aim and consume time and effort where it is most needed. The reuse aspect should be taken on case-by-case basis, it should be considered when socially and economically relevant.
5. A proper business model is required to set a fair tariff while ensuring the sustainability of the activity. The model should be developed with the actors involved in the operation of the DTF for it to suit with the local context.

I have attached the effluent quality test results of one of the DTF (Machakos). As you will see, the final effluent is not reaching the quality standards, therefore the UBSUP team is doing some adjustments in the operation procedures and is also working on a new DTF design to increase the capacity to 50m3/day and improve the general performance of the plant. I will keep you posted on the new design very soon.

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Alexandra Dubois

Technical Advisor
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Nairobi, Kenya
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  • alexandra85
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Re: Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

I am adding some pictures of the DTF in operation to illustrate my previous post:


Aerial shot DTF Chuka © WSTF/GIZ


DTF Machakos © WSTF/GIZ


Faecal sludge discharge in Nakuru DTF © WSTF/GIZ


Anaerobic Baffled Reactor in DTF Chuka © WSTF/GIZ


Sludge drying bed in Machakos DTF © WSTF/GIZ


Vertical flow constructed wetland in Homa Bay DTF © WSTF/GIZ


Operator office in Chuka DTF © WSTF/GIZ


Samples in Chuka DTF: incoming vs treated effluent © WSTF/GIZ

Alexandra Dubois

Technical Advisor
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Nairobi, Kenya
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Re: Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

Hello,
Thanks for the post. Happy to see the machakos plant operating well. I was there when it first received the faecal sludge.
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  • nicolag
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Re: Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

Alexandra, a few questions
1. Can you tell me where are the existing 7 and where the remaining 4 will be?
2. Do you know of other countries with such widespread networks of decentralised FSTPs?
3. In most cases are they now the sole provider of treatment in the towns/cities or a compliment to a central WWTP i.e. are they really decentralised, or more a small town solution?
4. Will they cope with heavy loading from pit latrines or are they design more with sludge from vac tankers in mind? You say you assessed the current market, but having local treatment facility in place puts these cities in a nice place to massively boost pit latrine emptying activities...if they really took off would the facility cope?
5. How are smell and pest issues- how close could somebody live? (not exactly, but could they be placed right beside some homes for example?)

Thanks for providing all of those documents and images -really great to see this well documented !

P.S. - here here...constant issue I encounter.
The topic of reuse and recycling is very trendy nowadays (biogas, fertiliser, briquettes, etc.) and might look very attractive from an external point of view, however it can easily divert the attention from the real aim and consume time and effort where it is most needed. The reuse aspect should be taken on case-by-case basis, it should be considered when socially and economically relevant

Nicola
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Re: Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

Hi Nicola

Nice to see you on the forum, and I am glad if you found the post informative. To answer your questions:

1. The 7 operational DTFs are located in Machakos, OlKalou, Embu, Nakuru, HomaBay, Chuka and Nolturesh. The 4 remaining ones are in Ongata-Rongai, Mwingi, Kibwezi and Molo

2. I don't know of any other country that has undertaken the activity of faecal sludge treatment plant at a national scale, maybe someone from the forum can tell us otherwise. The GIZ Water Programme in Burkina Faso will most likely start a up-scaling sanitation programme from 2019 which will include the construction of standardised decentralised treatment plants for faecal sludge.

3. Very interesting question: initially the UBSUP main objective was to provide improved toilets to people who don't have access to basic sanitation in designated low-income urban areas. While developing the concept, the team realised that in order to complete the sanitation chain, UBSUP could not omit the treatment/disposal aspect. Therefore, we came up with a decentralised low-cost technology to cater for the faecal sludge generated from the newly constructed and the existing toilets of the areas in question. So, to answer your question, the DTF has been designed and is being implemented to offer localised treatment of the faecal sludge produced in specific areas (UBSUP targeted low-income areas). The UBSUP project is not meant to provide faecal sludge and wastewater treatment for a whole town, city or region, it should not replace a conventional treatment plant, and must come as a complementary solution to a centralised treatment plant. However, the reality is that faecal sludge and wastewater treatment plants are too few and often, the DTF is used as the main treatment facility for the whole town (and sometimes the neighbouring towns).

4. The current DTF is designed for faecal sludge from septic/holding tank, meaning that the faecal sludge has a high water content and is brought in the DTF through vacuum tankers. Some tankers bring faecal sludge from pit latrines but with this type of thicker sludge, we are facing the challenge of high grit and solid waste content which tend to clog the control valve. The new DTF design will take care of this issue. Boosting the emptying service activities (mechanised) would be one of the achievement of the DTF and the UBSUP project as a whole. At the moment we are observing that most of the DTF are running below capacity, therefore there is still a certain leeway before reaching the maximum capacity. Once the DTF cannot cope with the demand anymore, it is a good indication for the water company or the local government to consider either some additional decentralised facilities or a larger conventional treatment plant.

5. For the current design, smell is not an issue because most of the treatment modules are enclosed with an adequate ventilation system. Smell is likely to come from the drying beds during a couple of days after sludge has been deposited, however for this design, the sludge drying beds are not used frequently (only for the occasional desludging of the anaerobic modules). In order to avoid any conflict with the community and increase acceptance of the project, it was recommended to construct the DTF at a reasonable distance from settlements.

I hope I managed to answer your questions, don't hesitate to ask more and if you can, try to visit some of the DTFs. I would be happy to hear your feedback and comments.

Alexandra Dubois

Technical Advisor
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Nairobi, Kenya
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Re: Key documents for Category 1 "Design and Technologies" (Decentralised Treatment Facilities)

Hi,
Nicola asked: "2. Do you know of other countries with such widespread networks of decentralised FSTPs?"

India comes to mind. See for example this discussion thread which talks about 78 Fecal Sludge Treatment Plants to be built this year in the state of Andhra Pradesh:
forum.susana.org/280-faecal-sludge-treat...andhra-pradesh-india

Wouldn't it be awesome if we could identify someone like Alexandra who utilises this forum to inform the world about their progress and learnings with these treatment plants?

Elisabeth

Community manager and chief moderator of this forum via SEI project ( www.susana.org/en/resources/projects/details/127 )

Dr. Elisabeth von Muench
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