Improved Pit Emptying Technology - Flexcrevator

  • rochelleholm
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  • Manager of Mzuzu University Centre of Excellence in Water and Sanitation, Malawi. To learn more about the Centre visit
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Re: Improved Pit Emptying Technology

In my observation in Malawi, towns with a population under 150,000 where pit latrines are a primary household system, only one formal emptying provider and a handful of informal emptiers can be sustained. In town of under 50,000 there are no regular formal providers.

In which case, I see that your ‘technology champions' would need to have a base population of more than 150,000 at least in their startup area.


Rochelle Holm, Ph.D., PMP
Mzuzu University
Centre of Excellence in Water and Sanitation
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  • shaji
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Re: Improved Pit Emptying Technology

Interesting . Can we change the final shape of the containers.
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  • nicolag
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Re: Improved Pit Emptying Technology

Rochelle - thank you ,that is a useful way to think about defining the market for one unit.

Very helpful Georges - thank you! I agree with what you say; I think those are similar thoughts to mine but expressed a lot more clearly. It seems like the next stage would need to a technical validation stage with those 'ideal' partners I think the question applies not only to the Flexcrevator, but maybe also to the eVac, the ROM, the Earth Auger etc.

There are some nifty products out there but the hurdle/expense to actually reach the market post product development seems universally underestimated. Do we have any success stories of new tech penetration via partners in this sector (or similar?!) Do we have any organisations specifically focusing on bridging this early stage market entry gap? Also interested if anyone has recommended reading around this, or indeed, business contacts who have gone through this process with tech before.

@georges in terms of those 'easier' market partners - who do you think we are looking at...
- Sanitation Solutions Group
- Pit Vidura
- Practica
- Sanergy

@shaji - what configuration is preferable to you? Similar to the unit that @JKMakowka pointed out in the thread? That group reconfigured to pump directly to the road. For now the set -up of the Flexcrevator is to those barrels but that suits some markets and not others. I'd be interested to know what set up you would want.
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  • FrancisdelosReyes
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  • I am a professor and environmental engineer at NC State University, USA. I am interested in wastewater treatment, WASH, microbial ecology.
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Re: Improved Pit Emptying Technology

Hello all,

We (Flexcrevator team from NC State) have been quiet for a while as we did field testing of several designs for trash exclusion.
We're happy to report that we have a nearly complete design that we tested in June/July in Kisumu, Kenya, taking the learnings from the previous testing in Lusaka, Zambia.

We hope to present the design at FSM5. Results from testing in Kisumu, Kenya (with assistance from WSUP and KIWASCO) are summarized below:

The prototypes were tested in several wet and dry pits with trash. The clearing auger-Flexcrevator was able to successfully and completely exclude trash in wet pits, with flow rates ranging from 3 to 4 lps. Emptying 1 m3 of FS took a total pump time of 3.8 min, and a total time (including handling barrels) of 27 min. Thus, the pump time was only 14% of the total operation time.

The Flex Excluder was attached to a commercial vacuum truck, and 4.7 m3 of trash-free FS was pumped out in 14 min (5.6 lps). In thicker sludge (> ~12% solids) the flow rates were much lower, ranging from 0.2 to 0.75 lps. Blocking due to fibrous material such as hair and food fiber were also a challenge in thicker sludge. The results of field testing, including the effect of sludge thickness and solids content, hole sizes, auger material, auger clearance, trash types and amounts, deflection vs. clearing, operation, user and customer feedback, among others will be presented at FSM5 (hopefully).

We apologize that we cannot share final design yet- we are in the process of making some tweaks to solve the issue with hair and fiber in thicker sludge (not watery sludge).

Francis de los Reyes III
Professor/TED Fellow
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