Experiments regarding pit emptying devices and clog-proof toilet (mechanical toilet that uses little water) - Ohio, USA

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  • dandreatta
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  • I am a mechanical engineer and work for a consulting company. I do projects around water, cookstoves, and sanitation in my spare time.
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Experiments regarding pit emptying devices and clog-proof toilet (mechanical toilet that uses little water) - Ohio, USA

This thread used to be here ("Who is doing toilet and FSM product and technology design?"):
forum.susana.org/forum/categories/53-fae...you-working-on#13171

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I'll add my 2 cents worth here. I am doing toilet and FSM technology design. I am an independent engineer working on sanitation in my spare time.

I've developed some prototypes of a pit emptying device, see



This is not a universal solution, of course, but should work well in some places, and is certainly better then the poor men climbing down into the pit.

I've also developed a low water clog-proof toilet, see



I've used this for a while and it works well, though it needs some changes.

I'm also working on an above-ground latrine made of a barrel for high water tables, which can be emptied using something like the mechanism shown in



This one is still in the early stages of development, so I can't claim too much yet.

Dale Andreatta, Ph.D, P.E.
Dale Andreatta, Ph.D., P.E.
Mechanical Engineer
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  • vishwanathdalvi
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

I really like the clog-proof toilet with the pivoting seat. Could you make it so that the seat could tip with less water?
Vishwanath H. Dalvi
R. A. Mashelkar Assistant Professor
Department of Chemical Engineering
Institute of Chemical Technology, Mumbai
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

Thanks for the interest in the clog-proof toilet. I've been slow to respond as my regular job has been keeping me busy lately. Since the video was made I've used the toilet for some time. The attached report contains pictures of the whole system and some test results.

The basic results are that the system worked as designed, though a few improvements are needed. The average water usage was 486 grams. Everything flushed (dumped) properly with no splashing or splattering. The odor was mostly contained within the vessel, though reduced gaps around the edges of the basin would have contained the odor better.

Regarding your question about whether the system could be made smaller so as to use less water, the basin could be made a little smaller, but not much. The basin was pretty full at times.

The attached report covers 4 sanitation solutions, the mechanical dumping toilet that is the subject of this discussion is the second solution and starts somewhere around page 5.

Thanks,

Dale Andreatta
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Dale Andreatta, Ph.D., P.E.
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

These ideas are very good as is the fact that you can flush with only half a litre of water. Why do you need to empty out the septic tank then? The fecal matter + water will have a very small volume which will keep decreasing as composting proceeds.
Vishwanath H. Dalvi
R. A. Mashelkar Assistant Professor
Department of Chemical Engineering
Institute of Chemical Technology, Mumbai
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

Dear Dale,
just now I came to read you material and to take a look at the videos. Congrats very interesting ideas. I would like to comment on some aspects. (I think your proposal should have a more prominent space as it is interesting - the titel of the thread is right, but not pointing to a really ineteresting solution)

a) the bucket (first video) really is a very interesting solution as a simple device for emptying dry pits... I think there might be some issues with the durability of the material, but that is all possible to solve I guess even with cheap material.

b) I don´t see the bucket as a good solution as demonstrated for liquid emptying, I guess it would be better to have a stick instead of the rope, by that you can tip the bucket and fill it more rapidly.

c) the tipping device is definitely a very interesting idea for pits in my understanding, I was impressed. I have seen it so often for measuring of volume but it never occurred to me for this application. For sure it is easy to close better the gaps between pit and bowl with a rubber seal (obviously that might be influencing the tipping weight). The bowl must be some sort of very anti sticking material (teflon like?), if not that might be a problem. But even with some “rests” better than an open hole . Attaching a thin rope at the back of the bowl going out below the seat at the back, would not be a solution to tip it without water? (yes a dirty hand could have pushed that rope… but the same hand might have opened the door as well…)

d) for the solar pasteurization device I do have some doubts. First of all I really appreciate the effort you put into that and the results you gained with so little resources. There are some BMG projects with more resources and less results out there. I think the temperature measurements are very interesting… BUT the collusion you are drawing .. I understand based on your trials with water solarization (please correct me if I am wrong) are dubious to me… will say. ..

1) the green curve was not measured, it was plotted due to your experience with water.. right?

2) Did you consider that UV has a strong influence as well for die off of coliforms in the case of water?

3) you speak of pathogens, I think you refer to coliforms? Not helminth eggs.

But again, congrats for the achievements they are food for thought.

To vishwanathdalvi. Do a calculation. 5 persons, 365 days 0,5l /water,use, 0,12 l/ feces,d,pe. = 1,1 m³/year
Where does that go?

Regards
Christoph
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

"To vishwanathdalvi. Do a calculation. 5 persons, 365 days 0,5l /water,use, 0,12 l/ feces,d,pe. = 1,1 m³/year
Where does that go?"

Hi!
I am glad you did the calculation for me :) The numbers line up with what I had imagined. :)

1.1 m3 is not a large volume (its a small water tank occupying about 10 square feet of floor space). Further, a lot of this is liquid, which can be drained and (as you suggested) sterilized with a UV Led.
The solid that is left over will, if properly aerated, degrade to mineral. So that 1.1 m3 can last decades without clearing.

I would love to hear your views on this.

With kind regards,

Vishwanath
Vishwanath H. Dalvi
R. A. Mashelkar Assistant Professor
Department of Chemical Engineering
Institute of Chemical Technology, Mumbai
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

Hi Vishwanath,
I do think you are on the wrong track! It is not possible as you are suggesting. And You misunderstood (maybe :woohoo: ) my obersvation.
a) 1,1 m³ is a lot if you have to get it out without access of a tanker
b) how do you solid separation?
c) how do you treat the liquid? Just to leave no doubt - I did not suggest to treat it with uv! And UV treatment for sure is not enough. you need a secondary biological treatment (as for every liquid which goes out of a solid separation.
d)

solid that is left over will, if properly aerated, degrade to mineral

How do you do that? That would be the solution for our problems!

Regards
Christoph

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Note by moderator: The answer by Vishwanath has been moved into this new thread:
forum.susana.org/forum/categories/53-fae...nd-wikipedia-article
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  • dandreatta
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Re: Who is doing toilet and FSM product and technology design / R&D and what are you working on?

Hi,

Again, sorry for the slow response, my regular job and some other volunteer work has kept me busy lately.

Thank you for the complements. Sometimes having a limited budget saves time by forcing one to work efficiently. Since Christoph has made the most comments, I'll respond mostly to his comments.

First, the 3 videos I presented are 3 separate ideas, they can be used together or separately. The pasteurization ideas (not shown in videos) are other separate ideas.

The pit emptying device has been developed further since the video was made. It certainly does need to be improved in durability and some other things, at this point I'm working on the basic idea to make it functional. There will be videos of better versions coming soon. The newest version is much more compact. To dump the bucket requires only gravity, as about 2/3 of the bucket is beyond the pivots. Pulling on the rope pivots the bucket up, and releasing the rope allows gravity to pivot the bucket down. It seems to work well for both very liquid sludge and more solid sludge. One thing I will do soon is find out how solid the sludge can be, as I have gotten feedback that sometimes the sludge is very solid, almostly like dirt.

Regarding the tipping basin, it was lined with a teflon sheet, and in the week that I used the device as my toilet most things did not stick to the teflon very much. I don't know of any less sticky surfaces. Maybe a surface that is very water repellent? Various levers and ropes could be used for manual dumping with no water, with the disadvantage that your hand or foot would be touching what someone else's dirty hand or foot has touched. Perhaps that is not such a big deal, since each user is touching the same door that others have touched.

Regarding the solar pasteurization, I also see some gaps in that design, mostly related to its performance. Of course, here at 40 degree North latitude we don't have tropical sun, and the performance was pretty marginal here in the northern summer. I did not include any UV effects, as I assume that the UV does not penetrate very far into the feces. According to Feachem and many others, the most heat resistant pathogens are enteric viruses, so the helminth eggs should be well cooked at these temperatures. The green line (showing log reduction of pathogens) was calculated from the measured temperature at the (assumed) coolest spot in the feces. The relationship between time, temperature, and die off was based on enteric viruses and based on data given in the famous work from 1983 by Feachem and others. The mathematics for relating time and temperature to die off are fairly simple, though I'll leave the details for another time.

For reference, I have attached the newest version of the document that talks about all these ideas, including the time-temperature-die off curves from the pasteurization tests. The 3 youtube videos are referenced in this document, as well as my recent tests with the dumping basin.

Thanks,

Dale
Dale Andreatta, Ph.D., P.E.
Mechanical Engineer

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