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The Sipper or Pit Life Extender : What kind of membranes are we testing?

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There will be two type of Sipper or pit life extender tested.

The first is a simple displacement pump without any form of membrane and where the outlet of the pump discharges directly into a soak away, so as to prevent any waste being dumped near the house. The aim is to test the market and see if HH would buy such a product.

The second will contain the membrane and this is where compromises will have to be made. The most likely would be micro membranes with the larger pores which would stop the bacteria, but not the viruses. These are cheap and durable and the main issue may be the surface area of membrane needed to achieve the required water discharge rates and how to clear the membrane fouling. Ultra filtration removes viruses, but likely to require power and a cross flow approach to make it work. This makes it more complicated and more expansive, but there may be market with richer HH living in higher rise blocks.

We do not want to get burdened by the need to producer a discharge of drinking water quality - this is where the Gates Foundation seem to be getting stuck. Apparently even conventional treatment plants are not effective in removing viruses and they are hard to detect using simple tests.

The moral question is perhaps around the poor have higher standard imposed on them than the rich. Also - the one step at a time is a better approach.

See link below for more details on membranes -

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So just for visual clarification, as a customer I am paying for a displacement pump installed in my latrine, a soak away (assuming I don't already have one), and all the plumbing works to connect the two together?

As an industry facilitator for pit emptying businesses, how could Sanitation Solutions introduce the Sipper in Kampala? The two approaches will be in competition with one another.

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You could view it that way, just like the canal owners opposed the building of the railways. The Sipper does not remove the thicker sludge and this remains in the pit and will need an emptying service to remove it It is a complementary product to the emptying service and SSG could make money from their sale and introduction. The market is large enough for both.

Steven Sugden gravatar imageSteven Sugden ( 2015-04-15 04:56:03 -0500 )edit
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Just to clarify - what we are now looking at whether the sipper could be used as a flush mechanism with the Sato pan. As long as the water pumped up was not too smelly and relatively clear it could be pumped out and re-enter the pit straight away as it washed the shit off the flap

Steven Sugden gravatar imageSteven Sugden ( 2015-11-27 06:10:18 -0500 )edit

Overall, Washi in India has undertaken some interesting research into the application of membranes in extracting the water element out of pit latrine whilst leaving the sludge and pathogens in situ within the pit.
A single membrane was found to clog with organic matter very quickly so a one stage process was not possible within the cost and design constraints. Their solution involves a three stage process, which has an impact on the devices design and how it can become a commercially viable scalable product.

First stage, a form of roughing filter to separate the highly contaminated effluent from the liquid. Washi tried a sand filter, a 800 µ cloth filter and a porous concrete filter. The sand filter clogged, the porous concrete gave poor results and the cloth filter worked best.

Second stage, activated carbon filters to remove the odour. No coliform reduction.

Third stage, a 5µ micro filter together with UV or a batch chlorination process to remove coliforms. The chlorination result were good but it required a long settling time and is fail to danger ie people will not buy the chlorine and discharge highly contaminated effluent.

Experiments were also carried out using aeration to increase treatment around the cloth filter.

The net result is a prototype continuous filtration process which can take effluent straight from the pit and discharge water which complies with India discharge standards. The prototype can has a discharge rate of 1.2 litres per minute.

For more info see

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This is the latest presentation of results from WASHI in India using membranes. They have also developed a mobile unit which replaces the need for using a treatment plant.

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Latest report on membrane research from WASHi in India

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2015-04-15 03:37:56 -0500
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Last updated:
Jul 07 '16