All the papers can be downloded from here for free

Thanks for bringing this paper to our attention. I include here your Figure 1 from the paper to draw more attention to it:



If someone wants to see all the papers from this project what's the easiest link for them to see them all together?

We've had a few publications from the Nano Membrane Toilet team recently but I think this one will be particularly interesting to the SuSanA audience:

Field testing of a prototype mechanical toilet flush

The Nano Membrane Toilet needs a waterless flush to reduce the amount of liquid that needs to be processed subsequently. A prototype was tested in a semi-public, institutional setting and in selected peri-urban households in eThekwini municipality, Republic of South Africa. The mechanism's functionality and users' perception of the flush were assessed. User perception varied depending on background: Users accustomed to porcelain water flush toilets were open to, yet reserved about the idea of using a waterless flush in their homes. Those who commonly use Urine Diversion Dehydration Toilets were far more receptive. The user-centred field trials were complemented by a controlled laboratory experiment, using synthetic urine, faeces, and menstrual blood, to systematically assess the efficiency of three swipe materials to clean the rotating bowl of the flush. A silicone rubber with oil-bleed-effect was found to be the best performing material for the swipe. Lubrication of the bowl prior to use further reduced fouling.

The full paper is available to download for free:

Jan Hennigs; Kristin T Ravndal; Thubelihle Blose; Anju Toolaram; Rebecca C Sindall; Dani J Barrington; Matt Collins; Bhavin Engineer; Athanasios J Kolios; Ewan McAdam; Alison Parker; Leon Williams, (2019) Field testing of a prototype mechanical toilet flush, Science of the Total Environment 668, 419-431
www.sciencedirect.com/science/article/pii/S0048969719307077

Thanks to all for your comments and interest!

The membrane will be modular. However, we would be nervous about installing the toilet without the membrane as the untreated liquid component will still be pretty nasty - basically feacally contaminated urine, which could cause significant groundwater contamination, depending on the local conditions. Our energy modelling suggests we will be able to get enough energy out of the faces to enable the membrane processes.

The membranes are hydrophobic so fouling is not too much of a problem (a paper on this is in preparation).

Alison

Dear Alison, dear Ecowater and all,
The idea of turning human waste into usable water, dry fertilizer and energy is great and the prototype of your design is beautiful. Congratulations!
As a membrane manufacturer, I agree with what Ecowater concerns about, the energy cost.
Very few water would go through the membrane fiber unless there is a pressure to force them to. To maintain the pressure consumes ennergy.
I see Alison and her team has been working on it to find the proper "selectivity". I think it might depend more on field data and sometimes, individual cases may differ a lot from each other.
Then it comes to the pollution resistance ability of the membrane itself. For a daily device for everyone, the least troublsome way is that it can clean itself when the fouling against the membrane module reaches a redline and we press a button for it to clean itself for two minutes and then it could go for another week. During this week, we may call and wait till the technician to arrive and replace it with the regenerated membrane module.
The called technician could be delayed by everything while the call of nature is absolutely not.
We have projects in Cambodia for membrane treated drinking water. The energy problem is tackled with bicycle generator.
Membrane technology opens a new gate to solve clean drinking water crisis and I'm happy to see that Alison and her team is working with it on human waste problem. I would be glad to share what we found in our application practice for this great idea.
Good luck!
Jack

Have you thought about making the membrane part modular? I guess in many cases the water recycling aspect is not that vital and a more simple filter for soil infiltration would do. However in cases where the water recycling is needed, a larger version that can also recycle various sources of grey-water in addition would be a good idea?

Dear Prince,
You might have overlooked Alison's response to your earlier request. She wrote on 6 December 2016:

Prince and Orchha - We're still in the development stage but I hope we'd be able to brign it to Kenya, Uganda and India in the future.

So I think you still need to be a little bit patient.
Regards,
Elisabeth

As interested persons in this project,we request if such can be replicated in Uganda or Kenya it can be of great value to communities of two countries.We too have great passion to recycle human urine into valuable products to generate job opportunities and reduce poverty. We shall be happy to have partnership with you on this project. Prince Maloba

We're still deciding on which membrane to use, but all the ones we are testing are off-the-shelf, none are bespoke. One of the key factors is selectivity - the more selective the membrane, the more energy is required, byt the better quality the output water.

Just to note that's its not an MBR process - more similar to pervaporation.

Aren't the membranes expensive?

How much energy is used to push the liquid through the membrane?

MBR for wastewater is running into all sorts of challenges in the U.S.

The screw is a critical component in the toilet, allowing the settled solids to be removed from the bottom of the holding chamber and transported towards the gasifier/combustor. This separates them from the liquid. Traditional source separating designs require a change of user behaviour, whereas our aspiration is to make using the Nano Membrane Toilet a comparable experience to using a "conventional" water-flush toilet.

We have been doing experiments on the screw to determine the best charactertistocs to transport the solids but minimise the transport of liquids. This has included changing the taper of the central shaft, makig the flights closer together near the top of the screw, and changing the rotation speed. the results are described in this recently published, free-to-access paper:

Mercer, E., P. Cruddas , L. Williams , A. Kolios , A. Parker , S. Tyrrel , E. Cartmell , M. Pidou and E. J. McAdam (2016) Selection of screw characteristics and operational boundary conditions to facilitate post-flush urine and faeces separation within single household sanitation systems , Environ. Sci.: Water Res. Technol., 2, 953-964

The membrane module is a core component of the toilet, allowing us to get clean water from faecally contaminated urine. Experimental work has defined the tube-side mass transfer coefficient derived in hollow fibre membrane contactors of different characteristic length scales (equivalent diameter and fibre length) under the slow flow conditions that are expected in the toilet.

The work is described in detail in a paper in the Journal of Membrane Science, which is free to download:

Yang, C.Y., E. Mercer, F. Kamranvand, L. Williams, A. Kolios, A. Parker, S. Tyrrel, E. Cartmell, E.J. McAdam Tube-side mass transfer forhollow fibre membrane contactors operated in the low Graetz range , Journal of Membrane Science 523, 235–246