Introduction to Hygienic Water Free Toilet (Reinvent the Toilet Challenge India) - Institute of Chemical Technology, Mumbai, India

  • vishwanathdalvi
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Introduction to Hygienic Water Free Toilet (Reinvent the Toilet Challenge India) - Institute of Chemical Technology, Mumbai, India

Hi All,

We are a group of scientists from the Institute of Chemical Technology, Mumbai. We have come up with an idea to use air to convey away fecal matter instead of water. Here is our introduction sheet:

Title of grant: Hygienic water free-toilet
Subtitle (more descriptive title): Using air to “flush” and a particle bed to seal.
Name of lead organization: Institute of Chemical Technology, Mumbai
Primary contact at lead organization: Dr. Parag R. Nemade
Grantee location: Mumbai, India
Developing country where the research is being or will be tested: India
Start and end date: December 2014 to December 2015
Grant type: (e.g. Global Challenges Explorations, Reinvent the Toilet Challenge, Other): RTTC
Grant size in USD: $30,000/- The grant is not listed in the database (it is given by the BIRAC organization of the Department of Biotechnology of the Government of India. The Grant reference number is BIRAC/GCI/0063/02/13-RTTC - Hygienic Water-Free Toilet)*

Short description of the project:
We propose to develop an advanced version of the dry toilet which is substantially maintenance free. We will do so by using a gentle stream of air to fluidize a bed of dry disposable particles onto which the fecal matter is dumped upon use. Due to variations in density and consistency of the fecal matter and the fluidized bed, the fecal matter will sink (a well known phenomenon in fluidization technology). We will devise a selective valve system at the bottom of the bed so that only the fecal matter and wetted particles of the bed will fall through leaving a clean dry surface for the next user.

Goal(s):
Our ultimate goal is to develop a hygienic toilet that can be “flushed” entirely by air and will result in a small volume of concentrated fecal matter, making disposal/treatment manageable in underserved localities especially where there is no plumbing infrastructure.

Objectives:
1. To demonstrate the proof of concept of this idea.
2. To optimize the valve design to minimize concomitant loss of bed material per “flush”.
3. To identify a library of non-toxic, widely available granular materials for use as bed-material.

Research or implementation partners: There are 6 scientists at the Institute of Chemical Technology who are involved in this project:
Dr. Parag Nemade (lead),
Dr. Vishwanath Dalvi ,
Dr. Ashish Misra,
Dr. Siddharth Kasthurirangan (now at the University of Mumbai),
Dr. C. S. Mathpati and
Dr. N. Jha.

Links, further readings – results to date:
We have been able to demonstrate/validate that wetted bed material and fecal matter analogues (e.g. flour dough) do indeed sink in a fluidized bed. We have just received our first prototype of the valving mechanism which we will test out and refine in the next month.

Current state of affairs:
We have just installed a prototype made out of glass and we will be conducting experiments and refinements over the next month.

Biggest successes so far:
Preliminary experiments gave us a number of ideas on how to keep bed material from falling out without using a physical barrier (e.g. a trapdoor). This was important since such a barrier would be prone to breaking/jamming. Our current prototype depends entirely on gas-flow to achieve the valving effect.

Main challenges / frustration: For the first couple of months the main challenge was poor access to prototyping facilities. That hurdle has been overcome and we have found a glass-blower who has shown great enthusiasm for implementing our ideas. Our next challenge is going to be setting up an automation system to control the air-flow. But that is several weeks away.

We will be putting up photos and videos over the next few weeks and months. Looking forward to your feedback.

With kind regards,

The ICT team


* See here on the discussion forum about the group of six sub-grants under BIRAC which were made as part of the Reinvent the Toilet Challenge India grant scheme:
forum.susana.org/forum/categories/139-gr...nda-gates-foundation

Vishwanath H. Dalvi
R. A. Mashelkar Assistant Professor
Department of Chemical Engineering
Institute of Chemical Technology, Mumbai
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
LinkedIn: in.linkedin.com/in/vishwanathdalvi
RTTC Project: forum.susana.org/forum/categories/141-ot...gy-mumba-india#13252
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  • JKMakowka
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Re: Introduction to Hygienic Water Free Toilet (Reinvent the Toilet Challenge India) - Institute of Chemical Technology, Mumba, India

This sounds like a great idea.

Will it require a compressor for the air-flow or would a fan be sufficient?

How do you plan to deal with the urine, and what do you think will happen in case of watery diarrhoea?

Maybe instead of trying to minimize the loss of material, use one that has moisture adsorbing qualities to aid the drying? That way one could probably also easily recycle a large part of the flushed material with a sieve.

Have you tried using commercial available clumping cat-litter/ silica-gel litter for it? en.wikipedia.org/wiki/Litter_box

Edit: The air should probably be sucked from the top of the bowl to remove smells and any dust that the air might blow up from cover material abrasion, i.e. you don't want your bathroom to be always covered with a thin layer of dust blown up from your toilet.

Microbiologist & emergency WASH specialist
Visit the new WASH Q&A at: WatSan.eu
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  • vishwanathdalvi
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Re: Introduction to Hygienic Water Free Toilet (Reinvent the Toilet Challenge India) - Institute of Chemical Technology, Mumba, India

"Will it require a compressor for the air-flow or would a fan be sufficient?"
We have tested it with a cheap leaf blower. Works fine.

"How do you plan to deal with the urine, and what do you think will happen in case of watery diarrhoea?"
Urine and ablution water (and watery diarrohea) will make the granular particles stick together, hence these will sink and the dry particles will remain on top. The wetted particles could be removed via the valving mechanism.

"Maybe instead of trying to minimize the loss of material, use one that has moisture adsorbing qualities to aid the drying? That way one could probably also easily recycle a large part of the flushed material with a sieve."
We would ideally like to have a solution in which the particle could be completely recycled. We have toyed with the idea of embedding iron filings in polymer beads so that they could be magnetically separated and returned to the user interface.

"Have you tried using commercial available clumping cat-litter/ silica-gel litter for it? "
We have 5 kgs of cat litter in our lab right now! Will keep you posted :)

" The air should probably be sucked from the top of the bowl to remove smells and any dust that the air might blow up from cover material abrasion, i.e. you don't want your bathroom to be always covered with a thin layer of dust blown up from your toilet. "
That is a really good point. We may need to make it so that the flushing action starts only when the toilet lid is closed ...

And thanks for the feedback and the sharpening!

Vishwanath H. Dalvi
R. A. Mashelkar Assistant Professor
Department of Chemical Engineering
Institute of Chemical Technology, Mumbai
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
LinkedIn: in.linkedin.com/in/vishwanathdalvi
RTTC Project: forum.susana.org/forum/categories/141-ot...gy-mumba-india#13252
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  • ekellogg
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  • I and my firm are interested in growing sustainable businesses that supply toilets to Africans of all income levels, especially those of low income.
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Re: Introduction to Hygienic Water Free Toilet (Reinvent the Toilet Challenge India) - Institute of Chemical Technology, Mumba, India

Have you any further progress since your last report of ~ a year ago?

Edwin Kellogg, PhD
Partner, Kellogg Consultants, LLC
Boston, Massachusetts
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