That's good to hear, Francisco.

A silica-impregnated drying bag system for sanitation was on the market about 10 years ago.

I watched this 2016 video and see they wisely are targeting the humanitarian market for arid climates:

If the bags are not biodegradeable and low cost, the market for them might be limited to humanitarian and camping.

I look forward to learning more as it is publicized. I imagine the $200,000 they have raised will cover the prototype and field testing.

Carol

Hi Carol,

I did not mean to use the MIT and Mass. funding to state that the technology is proven.
In theory, the passive evaporative membrane can work (and it is a polymeric membrane, not a desiccant). The devil is in the details- configurations, actual rates, etc.

In terms of cost, I have no idea. Similarly, in terms of scale up and business models, there are many questions that need to be answered.

I do have some confidence in the team, based on their business savvy and access to solid scientists. I also know that they are not some "fly-by-night" operation and I can vouch for the CEO's integrity

Cheers!

Thanks, Francis.

I emailed her but have not heard back yet.

The fact that it has MIT and state funding does not mean it is pre-proven.
I have two data points about that related to other MIT water-sanitation projects. And my own Massachusetts state-funded projects!
MIT and state agencies have to fund projects. They can only go on what the applicant states.

Could this be a bag material that actively pulls moisture out of the contents without leaking—and fast enough to keep up with the high volume of liquid that will go into it?
(Or is it about a dessicant added to the bags----a product that's already on the market.)

How much will these bags cost?
Sanitation schemes involving imported bags do not seem to catch on without outside funding.

What funding are they seeking now if they've already received funding for proof of concept?
I look forward to seeing the prototype toilets they have in use in Massachusetts, as you report.

We'll see!
I like toilet experiments.

I think skepticism is healthy- after all, "extraordinary claims require extraordinary evidence." (Carl Sagan)

In this case, the group behind this- (change:WATER Labs) include actual scientists and researchers, and the technology (passive evaporation using new polymeric membranes) has scientific basis. The group also has had funding and awards from MIT (Lemelson fund) and the Massachusetts Clean Energy Center, among others.

As a disclaimer, the CEO of change:WATER Labs is a friend, and has asked me to comment on some of their protocols for testing, although I do not have any insider information on the technology. My understanding is that they are trying to avoid funding arrangements and VCs with lots of strings attached.

Their website is here: www.change-water.com/home

Hopefully we will see prototype results soon, and actual toilets being used by more people (it seems like they have prototypes thatchy themselves use).

Best,
Francis

Hi, all.
I suspect this story is over-stated and the solution is not ready for prime time.

If her "breathable bag" system worked, she would show an example: a photograph featuring a mashed banana and some water dehydrating in the bag.

As stated above, this system would require the purchase of special bags. So far, this model has not taken on anywhere without subsidies.

Since the Gates Foundation dropped a lot of money on this topic, so many people have rushed to this topic, mostly presenting technologies and systems that already exist or would not be adopted by users due to expense and complexity.

This reminds me of the over-hyped story of the LooWatt, which is a collection toilet stool from which one removes a bag and puts it into an off-the-shelf biodigester. This grew out of an art student's project, a toilet stool made partly of human feces.
This is an example of how a story is over-interpreted.
It is also a helpful example to those who have viable technologies and solutions to present: that the press likes novelty stories and overstatement.

However, I will reach out to her to find out. (I am in Boston, USA part of the year.) I will report back.

Carol

Dear Diane

I have colleague who also used research on a solar aided toilet technology to dry excreta within the toilet system. However i'm no too sure of the percentage water removal. I will check a share the details of his study for your consideration. In the mean time i have read other document that state the water content of feces as 75-90%. I am not surprised that they are getting 95% liquid removal rate

Thanks for this info., and for the brochure. .It's always good to know what all the options are.

Diane

Dear Diane,

personally I'm not familiar with the technology you are referring to, however from my own experience I can confirm that it is possible to evaporate a significant part of the water content of excrements just by using natural evaporation potential.

Actually we are using this evaporation effect in our Sani Solar System (3psanitation.de/?lang=en) which was developed as a autonomous sanitation solution for countries with arid or semi-arid climate.

Under normal conditions in northeast Brazil for instance, the natural evaporation potential is about 6 to 7 l/ day and m2 in the worst case. To use this potential for sanitation issues it is necessary to provide a extended drying surface or air flow, avoiding contact of flies or other insects with the faecal residue.

Please find attached a brochure with a short description of our system.

Best

Jochen

++++++++
Note by moderator: More information about Sani Solar is also available in this thread:
forum.susana.org/suppliers-of-pans-seats...eas-with-hot-climate

Dear Diane,

If I remember correctly, feces is about 75% water. So, for 200 gram feces and 1.5 L urine per day, I come to about 3% of original volume if fully dehydrated (for which would need an oven). Therefore, a claim of around 5% volume after successful dehydration in their system seems reasonable. (I assumed that the density of solids in feces is close to 1 and that the solids from the urine are nil.)

If both urine and feces go into the bag and you have a family equivalent to 4 people using this bag as their only toilet, you need to vaporize something in the order of 7 liters of water per day. I have no idea how realistic that is, but I guess it should be possible in a dry climate. At first sight, I guess the bag could easily last a couple of weeks for a family. (Back of the envelope calculation says you would have an accumulation of approximately 1.5 kg per week of solids for a family of 4).

Some potential issues I see:

1) Do the contents of the bag dry out fast enough to keep smell at an acceptable level?
2) Do the pores in the bag that help the wicking of moisture get clogged or not?
3) How much airflow do you need around the bag to successfully evaporate the liquids?

It reminds me of this:

forum.susana.org/106-user-interface-tech...elaware-usa?start=36

EDIT:

Regarding cost, if a material that is manufactured in large volumes can be used off the shelf, I guess it would not have to be expensive. What happens with the bags after/during collection may be more of an issue. The material inside the bags will be dry, but not sanitized. Are the bags compostable? Or does a centralized treatment facility have to have a safe way (machine?) to empty and clean the bags. Can the bags be re-used after this, or are they landfill? Burning plastics is always a bad idea, so I would rule that one out.

Regards
Marijn

Can anyone tell us more about this container-based toilet, as written up in the Daily Beast? www.thedailybeast.com/how-a-toilet-that-...rce=articles&via=rss

The article doesn't mention price and doesn't mention how often one might need to remove the pouch of vaporized material (it says 5% of the excrement remains after vaporizing 95%). Sounds too good to be true.

Diane