The Nano Membrane Toilet (Cranfield University, UK) - new phase of funding until Jan. 2016
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The Nano Membrane Toilet (Cranfield University, UK) - new phase of funding until Jan. 2016 08 Feb 2013 12:52 #3409

  • AParker
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Our team at Cranfield University has been challenged to "Reinvent the Toilet". We propose a solution that uses membranes and electro-spray technologies to treat human waste on-site without external energy or water. The university received $810,000 funding from the Bill & Melinda Gates Foundation in August 2012 to produce a prototype in the UK by the end of November 2013 (in the Reinvent the Toilet Challenge (RTTC) Round 2 grant scheme).

Grant period: August 2012 until November 2013 (will apply for Phase 2 funding). Now extended until March 2014.

Overall goal:
Overall we will create a full on-site toilet system that turns faeces and urine (as a mixed stream) into pathogen-free water and sludge that cna be safely removed and converted to energy.

Short description:
Solids separation (faeces) is principally accomplished through sedimentation. Loosely bound water (mostly from urine) is separated using low glass transition temperature hollow-fibre membranes. The unique nanostructured membrane wall facilitates water transport in the vapour state rather than as a liquid state which yields high rejection of pathogens and some odorous volatile compounds. A novel nano-coated bead enables water vapour recovery through encouraging the formation of water droplets at the nanobead surface. Once the droplets form a critical size, the water drains into a collection vessel for reuse at the household level in washing or irrigation applications.

Following release of unbound water, the residual solids (around 20-25% solids) are transported by mechanical screw which drops them into into a coating chamber lined with a replaceable bag. Once inside the coating chamber, the solid matrix is periodically coated with a biodegradable nano-polymer. The nanopolymer coating serves to block odour and acts as a barrier to pathogen transport. The toilet will be powered using a modular hand crank or bicycle power generator supplied for household use that can also power other low voltage items (e.g. mobile phones).

The replaceable bag comprising the coated solids is periodically collected for transport to a locally sited small scale gasifier sized to accommodate around 40 toilets. Both toilet maintenance and solids collection will be undertaken with a trained operative responsible for the franchised area.

Research components and activities (all carried out at lab-scale in Cranfield):
- Testing of membrane pervaporation for separation of pure water from faeces and urine
- Testing of zeolite nanobeads to condense water and adsorb ammonia
- Development of electrohydrodynamic spray atomisation technology to eliminate odour
- Design of human powered electricity generator
- Overall toilet design, focussing on usability and desirability to get ready for demonstration and field-testing in UK (technology readiness level, TRL 6)
- Selection of technology for getting energy from sludge.

So far, we have presented the concept the Faecal Sludge Management Conference in November 2012:
www.susana.org/images/documents/07-cap-d...ld-university-uk.pdf

Video of my presentation at this conference:



Website:
The project has a website including a blog to which regular progress updates are posted:
www.nanomembranetoilet.org

Lead organisation: Cranfield University in Cranfield, UK
Project leader: Alison Parker

We welcome any comments and feedback.
Last Edit: 10 Dec 2013 15:42 by muench.
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Re: The Nano Membrane Toilet 10 Feb 2013 14:09 #3436

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AParker wrote:
Our team at Cranfield University has been challenged to "Reinvent the Toilet". We propose a solution that uses membranes and electro-spray technologies to treat human waste on-site without external energy or water. The university received $810,000 funding from the Bill & Melinda Gates Foundation in August 2012 to produce a prototype in the UK by the end of November 2013.


I would love to be able to "field test" the proposed solution. I am interested in seeing these types of technologies out of the laboratories and into lavatories.
Rowan Barber
Australian Sustainable Business Group
Engineers Without Borders Australia

Re: The Nano Membrane Toilet 11 Feb 2013 11:14 #3442

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Good day,
I find your proposal quite interesting, but have a problem with some of the aspects (personal view / opinion).
Firstly, you are expecting the user to provide the required power by having to use the hand powered generator. If the user does not do so, what then?
Secondly, and more importantly, you are proposing to encapsulate the briquettes sludge with a product that would contain plastic. This means that if introduced into the ground as a fertilizer, you would be introducing plastic into the ground, which will never break down, or, if used as a fuel, would be exposing the users to potentially dangerous gasses / fumes.
We have been processing human waste for some time, successfully, and know that to briquette sludge at 25% is not so easy.
Finally, most of the rural toilet users don't have ready access to toilet paper, and you will also find that many use the toilet as a garbage pit! So, a large amount of detritus will make up the bulk of the waste that needs to be processes. How do you envisage tackling that problem.
Looking forward to your responses to the above.
Massimo
www.parsep.co.za
Massimo Zanette -Parsep / LaDePa

Re: The Nano Membrane Toilet 11 Feb 2013 12:50 #3443

  • AParker
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Rowan - thanks for getting in touch. We're not planning on field testing until at least 2014 so I'll remember your offer then!
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Re: The Nano Membrane Toilet 11 Feb 2013 13:07 #3444

  • AParker
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Massimo - many thanks for your valuable feedback.

Massimo wrote:
Firstly, you are expecting the user to provide the required power by having to use the hand powered generator. If the user does not do so, what then?


We are planning to add some mechanism by which the toilet cannot be used if the battery is not charged. Obviously this needs to be accompanied by careful user education! If it transpires that the human powered generator is not going to be workable, we could use a solar panel (though these have their own accompanying challenges) or grid electricity (though this is outside the scope of the Reinvent the Toilet challenge). We also have an idea that the generator could also be used to charge mobile phoens, which adds extra utility to the toilet and potentially a source of income to the owners.

Massimo wrote:
you are proposing to encapsulate the briquettes sludge with a product that would contain plastic. This means that if introduced into the ground as a fertilizer, you would be introducing plastic into the ground, which will never break down, or, if used as a fuel, would be exposing the users to potentially dangerous gasses / fumes.


The plastic we are planning to use (polycaprolactone) is biodegradable so should not cause a problem for fertiliser and will be safe to burn.

Massimo wrote:
We have been processing human waste for some time, successfully, and know that to briquette sludge at 25% is not so easy.


I would be interested to learn about your experiences with 25% solids sludge. Are they documented anywhere? If necessary we may be able to extract more water so have a higher solids' concentration sludge.

Massimo wrote:
Finally, most of the rural toilet users don't have ready access to toilet paper, and you will also find that many use the toilet as a garbage pit! So, a large amount of detritus will make up the bulk of the waste that needs to be processes. How do you envisage tackling that problem.


At this stage we are not planning to deal with the type of detritus! But it is certainly not impossible and we may be able to deal with it in the future. Having said that, I think again user education is absolutely vital, accompanied in this case by a well managed solid waste programme!
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Re: The Nano Membrane Toilet 11 Feb 2013 17:17 #3447

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Dear Alison

Thank you for sharing your experiences on this ambitious invention!
I can understand that one might get critical as it sounds all quite complicated and high-tech! You may have already some ideas about futures maintenance requirements...

Besides using the hand crack - what other daily maintenance is required?
What are the expected overall costs for maintenance – does the usage costs remain under 0.05$/person/day as allowed by the Bill & Melinda Gates Foundation?)
What are the costs for the replacement of the membrane every 6 month and is this a membrane that would be easily available at large scale?
What other spare parts one may need and what about their availability and the skills needed for their installation?

With other words, where do you see the biggest niche or application area for the Nano Membrane Toilet?
And what planned (?) or potential collaboration with providers (i.e. spare parts / services) would be required to bring the Nano Membrane Toilet once out of the scale and up to scale?

Cheers, Dorothee
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Re: The Nano Membrane Toilet 11 Feb 2013 17:37 #3448

  • AParker
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Dear Dorothee,

Yes, I do feel a bit under the spot light. It would be good to hear from the other RTT grantees But it is good to have our ideas challenged!

I think that the hand crank will be the only daily maintenance requirement but we will see how the final design works out! The briquettes will need to be removed regularly as well, depending on the size of the collection hopper.

The membrane and beads do not need to be replaced - actually they are just regenerated at a central processing plant. We envision they will be replaced by a trained technician every six months. The polymer is a consumable but we are not sure of the cost yet as it depends on volumes used. The TRL 6 testing will reveal any other parts that are likely to fail and need replacing.

The toilet is designed for dense urban areas where pit latrines are not realisitic. I know B&MGF are already thinking quite hard about how to bring the Reinvented Toilets to scale and what local partners will be needed.

I hope this answers your questions!

Re: The Nano Membrane Toilet 12 Feb 2013 06:50 #3452

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Hi, Thank you for your response to my comments. One last item which I forgot to raise was the issue about pathogens, and the other nasty things. Your write up states that some of these would be killed off in the proposed process. I think this is probably the most serious part of human waste management and handling / disposal. Tests conducted by a university here in South Africa found that 15 years after human waste has been buried, the pathogens still thrived in the soil adjoining the buried waste! You should give this a bit more though with regards treatment for pasteurization.

Keep us in the loop. Thank you
Massimo Zanette -Parsep / LaDePa

Re: The Nano Membrane Toilet 12 Feb 2013 10:30 #3454

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Hello,
This process looks very interesting. Can it work with urine only ?
I ask that because if we do not mix urine and feces, it is quite easy to dry feces but urine is still a problem.
Do you do some test ?
Thank you and congratulation for this idea

Emmanuel
Ecodomeo
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Ecodomeo - France
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Re: The Nano Membrane Toilet 12 Feb 2013 13:53 #3457

  • AParker
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Massimo wrote:
Your write up states that some of these would be killed off in the proposed process. I think this is probably the most serious part of human waste management and handling / disposal. Tests conducted by a university here in South Africa found that 15 years after human waste has been buried, the pathogens still thrived in the soil adjoining the buried waste! You should give this a bit more though with regards treatment for pasteurization.


Thanks for hihglighting this. I would also be interested to see your results showing that pathogens are not killed even after 15 years! (As well as your experience with 25% sludge, above.)

We are not intending to pasteurize the sludge. This would be quite energy intensive! Rather the coating of the sludge briquettes will contain the pathogens so they are safe to handle.

B&MGF are supporting a disinfection working group made up of RTT grantees so it would be interesting to hear from members of that group.

Re: The Nano Membrane Toilet 12 Feb 2013 14:00 #3458

  • AParker
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emmanuel wrote:
Hello,
This process looks very interesting. Can it work with urine only ?
I ask that because if we do not mix urine and feces, it is quite easy to dry feces but urine is still a problem.
Do you do some test ?


Emmanuel - we have decided to design for a mixed stream of urine and faeces and avoid urine separation and its associated problems. If the toilet was used simply for urine the membrane could still work and extract pure water but the resultant "sludge" would not really be sludge, just very concentrated urine. So you'd need to develop a different way of dealing with this, I don't think the coating mechanism could work.

Re: The Nano Membrane Toilet 12 Feb 2013 14:20 #3459

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Thank you for your answer.

It is interesting to notice that you can concentrate urine with your membrane.
I work myself to develop a urine separation toilet without problem. I know that urine treatment (reuse or other) is the problem now in my case.
I keep that in mind when I try to star new research on urine treatment.
Thank you

Emmanuel
Ecodomeo
Emanuel Morin
Ecodomeo - France
www.ecodomeo.com

Re: The Nano Membrane Toilet 12 Feb 2013 15:20 #3462

  • AParker
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Please do stay in touch. We have an extensive research activity on membranes so may be able to help out with your future research.

Re: The Nano Membrane Toilet 15 Mar 2013 12:16 #3902

  • AParker
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The video of my presentation in Durban is now online if anyone wants to see it:

Re: The Nano Membrane Toilet (Cranfield University, UK) 04 Jun 2013 13:53 #4599

  • AParker
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See the latest blog post about the team's trip to Ghana to see sites where the Nano Membrane Toilet might be used:

nanomembranetoilet.blogspot.co.uk/2013/0...o-see-challenge.html

Re: The Nano Membrane Toilet (Cranfield University, UK) 22 Oct 2013 15:20 #6082

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Hi Alison,

I shortly want to go back to Massimo’s comment on the introduction of plastic to the ground through the briquette coating.

You mentioned that the coating you are using is biodegradable and that you were also considering recycling plastic bags as a coating. Those are generally not braking down fast and are not “biodegradable”. Are you still considering the recycling option bearing this in mind? Or would it require additional treatments to make the plastic biodegradable?

I have little knowledge in this field thus the answer might be obvious – still I am curious!

All the best,

Naomi
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Re: The Nano Membrane Toilet (Cranfield University, UK) 29 Oct 2013 17:11 #6196

  • AParker
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Hi Naomi,

Thanks for your question. Actually, we are now moving towards combustion/gasification as our final treatment method for the sludge so the biodegradability of the polymer will not be an issue. But you're right - using recycled bags would be a problem for biodegradability.

Alison

PS Keep up to date with what we're doing on our blog:

nanomembranetoilet.blogspot.co.uk/

Re: The Nano Membrane Toilet (Cranfield University, UK) 30 Oct 2013 00:19 #6200

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Hi Alisson,
Are you the principal investigator?
"The university received $810,000 funding from the Bill & Melinda Gates Foundation in August 2012 to produce a prototype in the UK by the end of November 2013."
Can you give us a sneak preview of the prototype? We are almost in November...
How would you explain "pervaporation", "super hydrophilic nanobeads" and "electrohydrodynamic spray atomisation" to a layman?
Do you have an idea of the projected range this is expected to cost?
Also, this project seems very ambitious (and it should considering the scope of the challenge), but I'd like to know, now that you are a year in, what compromises have you had to make in view of the initial idea and the practicalities of making this into a real system?
Thanks in advance...

Re: The Nano Membrane Toilet (Cranfield University, UK) 30 Oct 2013 13:47 #6212

  • AParker
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Hi Isis,

Yes, I'm the PI, so I'll try to answer your questions.

There's a photo of our works-like prototype on our blog:

nanomembranetoilet.blogspot.co.uk/2013/1...nearly-finished.html

The looks-like protoype is in the final stages of the design so I'll post an image of it soon.

To define the terms simply:
Pervaporation is a process by which water molecules are transported through a thin membrane wall. Pathogens and large molecules are excluded. This allows us to extract almost pure water from the waste, though that water is a vapour.
Super hydrophilic nanobeads are glass beads with a nanotechnology coating to which water vapour is attracted. When enough water has been attracted it forms a droplet which then drains downwards through gravity. We collect this water so it can be used in the home.
Electrohydrodynamic spray atomisation is a process by which very small bits of plastic (polymer) are sprayed onto the sludge. This stops odour and pathogens escaping.

The cost of the toilet is estimated at $750, though this does not include the gasifier that we are hoping to develop in the next phase of the project to extract the energy from the waste and complete the pathogen kill. However, we don't expect households to shell out this money upfront, rather it will be recouped through a service plan which as well as covering the capital costs will also cover the removal of the sludge, the servicing of the membrane and beads and the replacement of the polymer.

Compromises - I think the main one is the realisation that the dewatered material from the membrane may not have sufficient structure to stay together as a briquette. We've added a dewatering screw press (we needed this to move the material through the toilet anyway) and we're now going to collect the sludge in a bag rather than as a fully sprayed briquette that could be handled. We would also like to develop a community scale gasifier which will be fed by this waste so we don't really see this as a compromise. The remaining challenge is to reduce the energy demand of the whole system so it can truly operate off grid eelctricity, powered by our human generators.

I hope this answers your questions but happy to answer more!
Last Edit: 11 Dec 2013 12:11 by AParker. Reason: link was wrong

Re: The Nano Membrane Toilet (Cranfield University, UK) 31 Oct 2013 14:07 #6232

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Hi Alisson,
Thanks for your email. Your idea sounds amazing, btw!
So, from what I got from your explanation, the pervaporation process is akin to a membrane filter. In this case, as you are excluding most microbes, what is the risk of "biofouling" your pervaporator? How will this be addressed?
Nanotechnology, pervaporation and electrohydrodynamic spray atomisation aside, how easy will this design be scalable? That is, do you envision someone being able to replicate it as an open source technology or will there be a "monopoly" of the market by the business that has the specialised knowhow? (not that a monopoly is necessarily a bad thing)

Re: The Nano Membrane Toilet (Cranfield University, UK) 04 Nov 2013 15:09 #6264

  • AParker
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Hi Isis,

Yes, we'll exclude all microns - they are much too big to fit through the membrane! There is no risk of biofouling as the water passes through the membrane as a vapour.

We see the business operating as a franchise. There will need to be a certain number of toilets within a geographical area for it to be profitable, so I think they would have a monopoly for that geographical area.

Alison
Last Edit: 05 Nov 2013 10:38 by muench.

Re: The Nano Membrane Toilet (Cranfield University, UK) 05 Nov 2013 04:39 #6269

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Thanks Alisson for this. However, in order to form a biofilm in addition to the obvious microbes, a surface, moisture and a substrate are needed. It seems to me that all of these "ingredients" will be present on the retentate side of your membrane. What you are describing is not very different from most conventional membrane applications. Not sure I follow how there will be "no risk of biofouling."
From what you describe it seems that once the water passes it will be in the form of vapour, but before that it could be potentially available for a biofilm, no?

Re: The Nano Membrane Toilet (Cranfield University, UK) 05 Nov 2013 13:58 #6276

  • AParker
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Hi Isis,

Sorry, should have explained further - the membrane is also hydrophobic so is not wetted.

Re: The Nano Membrane Toilet (Cranfield University, UK) 07 Nov 2013 22:51 #6303

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Hi Alison,

think that the approach is interesting: it's novel, but also leading to add-ons like filters and catridges, and thus requires logistics. So there is a business model needed to cover for such expenses. Presume you have compared this approach with more common approaches, eg seperate liquid solid fraction toilet and composting, how does it compare?

best regards Winfried
Awaiting your suggestions, comments,

best regards Winfried Rijssenbeek

Re: The Nano Membrane Toilet (Cranfield University, UK) 08 Nov 2013 14:27 #6309

  • AParker
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Hi Winfried,

You're correct, we are also devleoping a business model for servicing the toilets.

Of course UDDTs and composting toilets are other options. I think there are some places where they've worked really well, and others where they've worked less well. I see the whole of the Reinvent the Toilet Challenge as broadening the sanitation technology options available, so there is a solution for all the diffferent contexts we find globally. Maybe other RTTC teams have something to add here too?

I'm not sure if that answers your question - was there a particular aspect you wanted me to compare the Nano Membrane Toilet and UDDTs/composting toilets on?

If you're interested to hear more we'll be part of the fourth webinar on 26th November (see here: forum.susana.org/forum/categories/139-ge...day-26-november#6427) and there is now an option to follow (subscribe to) our blog:
nanomembranetoilet.blogspot.co.uk/

Alison
Last Edit: 18 Nov 2013 14:03 by muench.

Re: The Nano Membrane Toilet (Cranfield University, UK) 17 Nov 2013 11:26 #6408

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Hi

You mentioned its for dense urban areas, which part of the world are you looking at?

What roughly will be the cost.

Living in Africa, people have mixed feelings about using bio-gas, I know of one hospital where they have a Bio-gas plant installed to use for cooking, but the staff wont use it because of the different odour it gives off, are afraid of getting some ailment or disease from it.

So handling the briquettes will pose another problem. Human waste is different from animal. Talking of briquettes, people here don't see sawdust briquettes as a source of cooking, a lot of sawdust and shaving wasted.

You said it will be franchise, the final costs will escalate.

Thoughts on the end product

Pete
Last Edit: 17 Nov 2013 11:26 by peteuk.

Re: The Nano Membrane Toilet (Cranfield University, UK) 18 Nov 2013 13:48 #6430

  • AParker
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Hi Pete,

We haven't desigend it for a particular part of the world though a lot of our work has bene informed by a visit the team made to Ghana:

nanomembranetoilet.blogspot.co.uk/2013/0...o-see-challenge.html

We are not generating biogas so we won't be affected by the taboos surrounding biogas which we are well aware of.

We've also changed our plans so we won't require the users the handle the briquettes - the sludge will be collected by a waste collector. You can read our latest description of the toilet here:

www.nanomembranetoilet.org/index.php

I'm interested in your throughts that with a franchise the final costs will escalate - can you explain more?

Alison

Re: The Nano Membrane Toilet (Cranfield University, UK) 19 Nov 2013 09:21 #6439

  • dorothee.spuhler
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Dear all

I would like to announce that Alison Parker will be participating in the next expert webinar hosted by SEI on Tuesday 26 Nov at 16:30 CET.

During this webinar, you will get the chance to see a live presentation of the project and recent achievement and ask questions. The programme is the following:
Introduction
Presentations (5 min presentation, 10 min discussion)
(1) Nano Membrane Toilet (Cranfield University), Alison Parker
(2) New concepts for on-site sanitation based on bio-additives and pit design (London School of Hygiene and Tropical Medicine), Jeroen Ensink
(3) Sol-Char Toilet: Using Concentrated Solar Energy to Stabilize Fecal Waste and Produce a Valuable Soil Amendment (University of Colorado, Boulder, USA), Richard (Chip) Fisher and Ryan Mahoney
Wrap-up

Attendance at this webinar is open!
Once recorded, the webinar will also be put online on the SuSanA Youtube channel.
See here for more information: forum.susana.org/forum/categories/139-ge...day-26-november#6427 or contact: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Best regards
Dorothee
Dorothee Spuhler
WG1 Co-lead
Working with Sustainable Sanitation and Water Management (SSWM) based at at seecon, Switzerland
www.sswm.info / www.seecon.ch
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Last Edit: 25 Nov 2013 23:41 by dorothee.spuhler.

Re: The Nano Membrane Toilet (Cranfield University, UK) 24 Nov 2013 09:23 #6517

  • AParker
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Lead post on this thread now updated, i.e. this one:
forum.susana.org/forum/categories/105-pr...d-university-uk#3409
Last Edit: 24 Nov 2013 14:46 by muench.

Re: The Nano Membrane Toilet (Cranfield University, UK) 10 Dec 2013 22:48 #6662

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Dear all,

I am writing this post to provide people who don't have access to Youtube videos with a quick overview of what Alison presented during the fourth webinar that SEI organised on 26 November (see Arno's post about it here: forum.susana.org/forum/categories/139-ge...12&start=12#6564).

Alison’s presentation starts exactly here in the Youtube video:
youtu.be/5BSbcB1H4kQ?t=3m32s
(the total duration of presentation and Q&A session was 16 minutes)

Title: Nano Membrane Toilet
by Alison Parker, a lecturer at Cranfield University

The powerpoint slides that she used:

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Note a more detailed presentation from November 2013 is available here on the project's website:
www.nanomembranetoilet.org/publicationsandreports.php

Schematic of the different components making up the system (taken from the more detailed presentation mentioned above):

reinventingthetoiletecrwash.jpg



Notes that I took from her presentation to explain the processes/toilet:
  1. This will be a household scale toilet, which should fit into a bathroom. It should be aspirational and desirable.
  2. They thought it was critical to have a flush mechanism – but not with water. The “flush mechanism” separates the waste from the user (both visually and in terms of smell). There is no urine diversion. As the lid closes, the bowl rotates; it is subsequently scraped clean (follow-up questions: do you have photos of this? Does this scraping mechanism really work well in the longer term?)
  3. The waste enters a chamber where the hollow fibre membranes are located. These membranes are there to reduce the liquid content of the waste. The membrane is hydrophobic (= repels water) and it doesn’t foul. Water vapour goes through the membrane, but water in a liquid state doesn't; this water vapour is condensed on beads which are in bead columns. They are experimenting with different materials for the beads: glass, silica. The beads are super-hydrophilic to attract the water.
  4. The driving force to push the water vapour through the membrane is a sweep gas. They had initially intended to use a vacuum pump but a sweep gas is proving more efficient. (I don't know what sweep gas is, Alison told me: A sweep gas is a dry gas that’s passed along the inside of the membrane fibres – it has the same effect as the vacuum).
  5. The water that is condensed on the beads from the vapour is extremely clean (could in theory even be drunk) – could be used for washing clothes or around the house in general (follow-up question: how much water would be “generated” in a normal household in this way? As it is only the water from the urine and some from the faeces, it is only 2 L per person per day or so? Is it worth all the effort for this small amount of water? Is it mainly because otherwise one would have the issue of having to transport this liquid out of the house?).
  6. The remaining solids sludge (25% solids content, i.e. 75% water) goes to the nanomister via a screw conveyer: here a mist of water and polymer is applied with nano-particles (this is where the term “Nano-Membrane Toilet” comes from). This creates a coating over the solid waste to limit pathogen spread and odour. (follow up question: 25% solids content strikes me as quite low, given that normal faeces has already 20% solids content. This is telling me that not much water is removed in the process with the membranes? Only the liquid from the urine really and nothing from the faeces, correct?)
  7. In the photo of the works-like prototype (see below) you see in the front middle the chamber with the membranes (currently at the end of a cycle); towards the bottom you see the solids that have settled; towards the right is a screw press to move the solids to the nanomister; on the right side you see the nano mister to apply the coating. The flush mechanism is not shown in the prototype. - Do you have a photo of the flush mechanism?
  8. Power for the toilet will be by human power (hand crank or bicycle); only minimal power is required: for the membrane (to supply the sweep gas, for the screw pump and for the nano-mister. (could you quantify the total power requirement by comparing with a 60 W lightbulb?)
  9. The coated solids would be removed from the toilet about once per week (by a service provider). Then they want to extract energy from the solids in a more centralised facility, e.g. for 40 households (why only 40?). They are talking to different companies like Janicki Industries (www.janicki.com/) and Uniliver (or in fact DPS Ltd - a company who are, like Cranfield Uni, a subcontractor on Unilever’s Reinvent the Toilet grant); also looking at a small pyrolysis unit.

Questions from the audience:

(1)
Question by Luiza Campos: "How is the water treated for reuse?"

Answer by Alison:
"Water that passes through the membrane (as vapour) is pure water – maybe only still containing some volatile organic components and ammonia, but nothing else; The ammonia and VOC are adsorbed on the beads. The beads are there to condense the water that has passed through the membrane.”

(2)
Question by Luiza: "How does the cost of such a toilet compare to a UDDT?"

Answer by Alison:
"Like all the grantees, we are aiming for less than 5 cents per user per day – we think we can make that. It may look high-tech but all the components are off the shelf components, including the membranes. The energy generation from the faeces could offset some of the costs in future. We still have to do detailed financial modelling.”

(3)
Question by Dorothee: "What actual testing have you done so far – with real faeces?"

Answer by Alison:
"We have only tested the system with synthetic faeces. We would like to use real faeces but we don’t want to make the unit unclean because it will need to be exported (to India for the fair in March) and we might have problems then with the transport.”

(4)
Question by Marc Deshusses: "Have you observed a decrease in permeability of the membrane over time due to a growing biofilm?"

Answer by Alison:
"We are not expecting problems with fouling because the membrane is hydrophobic and doesn’t get wetted. Only the water vapour passes through. But we haven’t done long-term tests yet. However, this is not a novel membrane, it exists as an off the shelf membrane.”

(5)
Question by Nelson: "Is the recovered water really pathogen free?"

Answer by Alison:
"As we have not tested the toilet with real faeces we have no proof but it is theoretically not possible that pathogens pass through the membrane (the holes are too small). So the liquid will be pathogen free." [Obviously for the faeces, they still contain pathogens, although this is coated with the nano-polymers to provide a barrier].

(6)
Question by Nelson: "Have you done tests on the nutrient value of the faeces product (N, P, K)?"

Answer by Alison:
"We will thermally process the sludge and the nutrients are not of interest to us (they will be lost). We think that this will be more cost effective, i.e. that energy recovery from the faeces will be more cost effective than trying to reuse the nutrients in the faeces. We think that reusing nutrients in urban areas is too challenging, although we would be happy to hear from others about cases where this has worked.”

If anyone has further questions or comments, then please put them here by replying to this post.
Thank you again to Alison for giving this presentation and for answering our questions!

Regards,
Elisabeth
Dr. Elisabeth von Muench
Independent consultant
Frankfurt, Germany
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Last Edit: 11 Dec 2013 12:30 by muench.

Re: The Nano Membrane Toilet (Cranfield University, UK) 11 Dec 2013 11:38 #6669

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Thanks for this great summary, Elisabeth!

To answer some of your outstanding questions:

The flush mehcniams is still beign built so we don't have any photos of it yet but there's a video of how it will work on our blog.

Yes, it is just the urinary water and some of the faecal water that is separated out. But this vastly reduces the volume of the unsafe waste that needs to be dealt with and provides waster in hioems where otherwise water can be expensive, time consuming to collect and only available intermittently.

We're still working on reducing the energy requirement of the toilet so we can't publish the total energy requirement yet.

Happy to answer any other questions this raises!

Re: The Nano Membrane Toilet (Cranfield University, UK) 24 Apr 2014 17:40 #8323

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See our latest blog post with photos from the Reinvent the Toilet Fair in Delhi, a video tour of our stand (made by Elisabeth and Arno) and downloads of the posters and brochures we had there.

nanomembranetoilet.blogspot.co.uk/2014/0...reinvent-toilet.html
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The Nano Membrane Toilet (Cranfield University, UK) 26 Apr 2014 22:04 #8342

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I am attaching some photos of Alison's exhibit from the Toilet Fair below, for people who cannot view the Youtube videos that are included in her blog post.

You find them all in this album on flickr:
www.flickr.com/photos/gtzecosan/sets/72157644242995466/

The vision of a toilet that is small - and pleasant - enough to fit inside someone's home (prototype but not fully functional) by Sustainable sanitation, on Flickr

Inside the Nano Membrane Toilet with bowl in mid-rotation of flushing mechanism (no water used) by Sustainable sanitation, on Flickr

A prototype of the flushing mechanism by Sustainable sanitation, on Flickr

Solid-liquid separation and diffusion of water through hydrophobic membranes in the front unit. Deposition of water droplets on nano-coated beads in the tubes in the back. Transport of solids through the mechanical screw that points up and to the right. by Sustainable sanitation, on Flickr


P.S. Here is the link to the interview I did with Alison about the research project in general:



And here is the technical explanations on their exhibit:



And here is a professionally done promotional video explaining the concept:

Dr. Elisabeth von Muench
Independent consultant
Frankfurt, Germany
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Last Edit: 26 Apr 2014 22:06 by muench.

Re: The Nano Membrane Toilet (Cranfield University, UK) 29 May 2014 14:30 #8776

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The Nano Membrane Toilet will form part of an exhibition for Universities Week 2014 at the Natural History Museum in London from 9 to 13 June.

Researchers from Cranfield University will join teams from 44 other UK universities represented at the Museum during the week. The exhibition will include research stations, pop-up performances, debates and live research demonstrations, covering a range of research themes.

The exhibition will be open every day from 10am to 6pm, with late night opening until 10pm on Wednesday 11 June. Cranfield’s Nano Membrane Toilet exhibit will be part of the ‘Environment and Sustainability’ theme and will be based in the Atrium. We’ll have all our prototypes so plenty of chance to try them out. You can see how much power you can generate with our hand crank generator. You can try our waterless flush. You can see our hydrophobic and hydrophilic coatings in action. And you can even sit on our toilet!

There’s a full list of all the events happening for Universities week here:

www.universitiesweek.org.uk/

Re: The Nano Membrane Toilet (Cranfield University, UK) 30 May 2014 11:20 #8791

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Hi Alison,

Congrats on this event. It is great to get the word out.

You say "We’ll have all our prototypes so plenty of chance to try them out" and then you say "And you can even sit on our toilet!", which seem to contradict each other a bit. Optimally, all the users who like should be able to use the toilet and see what the user experience is like. Any chance of that?

Good luck with the exhibition,
Chris Canaday
Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com

Re: The Nano Membrane Toilet (Cranfield University, UK) 30 May 2014 11:26 #8792

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Hi Chris,

The exhibition is open to the public so anyone can come to visit, but I appreciate that the average Londoner probably isn't our target user! BMGF don't want us to do full scale field trials yet, but we hope to gain a lot more user perspectives in our next phase of work. I can't publish our full plans yet as they are still under discussion but I'll keep you updated. If there's any aspect you think we should be specifically seeking user feedback on I'd welcome your input.

Alison

Re: The Nano Membrane Toilet (Cranfield University, UK) 19 Sep 2014 16:35 #10245

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[Start of Page 4 of the discussion]


We are delighted to announce that the Nano Membrane Toilet has received further funding from the Bill and Melinda Gates Foundation to continue the development of the toilet. This next phase will take us to January 2016 when we will have a prototype ready for field testing. We're really excited to be starting work again after a 6 month break.

Read more about our plans on our blog:
nanomembranetoilet.blogspot.co.uk/2014/0...toilet-receives.html

As ever, happy to answer your questions and receive your feedback on this forum.
Last Edit: 22 Sep 2014 13:34 by muench.
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Re: The Nano Membrane Toilet (Cranfield University, UK) 22 Sep 2014 13:33 #10258

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Dear Alison,

Congratulations on receiving this next phase of funding! That's great news for you and your team!

Can you tell us the size of this new grant (it is not yet visible in the BMGF grant database)?

And I read on your blog:
The biggest change is that rather than coating the dried solids, we're now looking to combust them in the toilet using a gasifier - we'll be working with RTI * who are already testing their gasifier in India. This changes the energy balance of the toilet, for example we can now consider recovering the water using a heat exchanger instead of the beads, and we won't have to use the bicycle power generator or hand crank to power the membrane processes.

* The RTI project is described here on the forum: forum.susana.org/forum/categories/105-pr...tional-usa-and-india

Could you tell us a bit more why you abandoned the coating and bead ideas?
And are you going to try and embed the gasifier in your small toilet model? I would find that a bit scary to be sitting on something that operates at high heat and with combustion... Would a unit like that really make sense at household level with all the associated safety issues? And wouldn't it increase the costs a lot?

Regards,
Elisabeth
Dr. Elisabeth von Muench
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Last Edit: 22 Sep 2014 13:34 by muench.

Re: The Nano Membrane Toilet (Cranfield University, UK) 22 Sep 2014 14:53 #10260

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Dear Elisabeth and everyone,

In our latest conversations with BMGF they really liked our small footprint aspirational concept:

1.bp.blogspot.com/-DfAaT4p68uI/U58oK4X1U.../20140609_102615.jpg

But they didn't like our plan to collect the solids weekly. So they suggested we pair with another grantee who could help us process the solids in the toilet, hence the link to RTI. With onsite solids processing there's no need for the coating so we're not taking this any further. We'll need to work hard to keep is both safe and cheap. It will operate as a batch process. So we'll automate it to operate when it's not being used. And we're going to gauge responses from households in Ghana about how they feel about having such a unit in their homes, as well as feedback from, RTI's ongoing field trial in India:

abettertoilet.org/field-work/

Hope that answers your question, do keep asking them!

Alison
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