Dear Hector,

Thanks again for your insightful question. We're still not concerned about biofouling due to the membrane materials. But we are a bit concerned about the formation of salt crystals on the membrane surface - these would be derived predominantly from urine. So this is what one of our post docs, Olivier Autin, is looking at.

I hope this clarifies this and if you have any other questions then Olivier and I can try to answer them!

Alison


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Note by moderator: This thread is now closed. Further discussions can take place in this thread:
forum.susana.org/forum/categories/105-pr...lts-publishing-stage

OK thanks.
I read from previous posts that you mentioned that there was no risk of biofouling (due to the material being used), which was the first thought I had when "membrane" was mentioned. However, I see that there are biofouling experts on the project team. So, is this a potential problem now?

Dear Hector,

I'm sorry if the posts above are not clear. The membrane is still a core part of the toilet, allowing us to dewater the waste for combustion and produce clean water. The membrane relies on nano scale processes for its operation.

I hope this is clearer but if there's anything else just post here or drop me an e-mail!

Alison

If there is no more membrane, then what is the innovation? What does the nano refer to?

I've just made a new blog post about the team's visit to Ghana to gain perspectives of potential users:

nanomembranetoilet.blogspot.co.uk/2015/0...potential-users.html

Hi Dennis,

Thanks for your questions and your honesty. It is much appreciated and I do share some of your concerns! I've just updated our blog with some of our latest development activities which might interest you.

denniskl wrote: I see that the grant period was extended to March 2014; I went to your website but didn't really get a sense of where you are, progress-wise.

are you field trialling yet? if so, where and what results?

Our phase 1 grant finished in March 2014, and our Phase 2 grant started in September 2014. We decided (together with BMGF) to not move into field trials yet but to spend some more time developing prototypes in the lab. However, we have a team traveling to Ghana in January to get a better understanding of target users' needs.

denniskl wrote: and did you sort out the likely production costs?

I acknowledge your financial modelling sees a less than 5c per day per user outcome, but the sheer tech involved frightens me:) from the capex (initial purchase / installation), a transportation and installation viewpoint and an ongoing maintenance / servicing / operational cost perspective

Yes, 5c per day is our target but we're still at a relatively early stage of development. However, we're looking at using off the shelf components where possible to keep costs down.

denniskl wrote: Membranes, beads, scrapers, rollers - really? in the remote communities of developing countries? (Note my bias here?

The servicing, spare parts, harsh environments, damage from floods, and just general wear and tear must see high servicing requirements (not to mention the possible damage en-route, incorrect installation and usage, etc).

Has the team explored these areas of actual implementation?

Our target market is not remote areas, rather urban areas. The toilets will be rented to the households and the rental cost will include servicing by a local technician who will also be on hand to deal with any faults.

denniskl wrote: I think your design is wonderful and in certain settings (even developed countries) it looks a viable alternative to minimise waste of treated water and even re-use of nutrients (can you re-use faces after you polymer wrap them?) but as a solution for an outlier village with 100% OD, I have to say I'd be more than a little sceptical (as I am with most of the Gates design winners, so it's not just yours) (Bias rears its head again here:)

Just one point here - we're not developing the polymer wrap any more - we'll now be combusting the dried faces directly in the toilet, as explained in an earlier blog post. an earlier blog post

Hope this helps, do keep asking questions!

Hi again alison; just following up on last post requesting update?

FOR FULL DISCLOSURE - I should advise that I am not a fan of the Gates "Redesign the Toilet" competition - I felt it was biased towards "sexy" designs rather than actually useful ones, so the below may come across as biased (and it probably is); I leave you to decide whether to answer:)

Not politically correct to be anti-the millions of $$ being shovelled to toilet designers by the Gates foundation, but there you are...

But notwithstanding that, I have some specific questions Alison if you don't mind

Q's;

I see that the grant period was extended to March 2014; I went to your website but didn't really get a sense of where you are, progress-wise.

are you field trialling yet? if so, where and what results?

and did you sort out the likely production costs?

I acknowledge your financial modelling sees a less than 5c per day per user outcome, but the sheer tech involved frightens me:) from the capex (initial purchase / installation), a transportation and installation viewpoint and an ongoing maintenance / servicing / operational cost perspective

Membranes, beads, scrapers, rollers - really? in the remote communities of developing countries? (Note my bias here?

The servicing, spare parts, harsh environments, damage from floods, and just general wear and tear must see high servicing requirements (not to mention the possible damage en-route, incorrect installation and usage, etc).

Has the team explored these areas of actual implementation?

I think your design is wonderful and in certain settings (even developed countries) it looks a viable alternative to minimise waste of treated water and even re-use of nutrients (can you re-use faces after you polymer wrap them?) but as a solution for an outlier village with 100% OD, I have to say I'd be more than a little sceptical (as I am with most of the Gates design winners, so it's not just yours) (Bias rears its head again here:)

Hi Alison, it's probably elsewhere in the forum but how is the progress?

I think you were due to field test in 2014?

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

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

[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.

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