I have a concept in mind for solar thermal treatment and assisted dehydration within the urine diverting dehydration toilet (UDDT).
Using a 12v 100w silicone heating pad inside the UDDT chamber and a designated solar panel for the energy source I believe it may be possible to kill all pathogens using a 2 chamber system. The heating pad that I purchased is like the one sold on this link:

www.aliexpress.com/item/100X100mm-100W-1...ment/2052207844.html?

I have not yet tried this and it is merely a hypothesis at this stage. The reason for us wanting to try this system is to enable micro dwellings (tiny houses) to be placed anywhere because they comply with health standards. We just want to kill the pathogens; fast.

The 100 watt 12 volt solar panel would be designated to the silicone heat pad. The pad would only heat up when the sun provides sufficient energy.

I would like your thoughts regarding the feasibility of the concept.

Harry Tams
Youth Futures Inc
Tasmania

Dear Kevin,

Currently, there are only a few application of solar drying for faecal sludge treatment. The sanitation group PIVOT in Kigali, Rwanda, employs greenhouse for the drying of dewatered faecal sludge. The group SANIVATION applies solar thermal energy concentration for the pasteurization of sludge. The group SANDEC has led trials of faecal sludge drying in greenhouses in Dakar, Senegal. So far, these are the unique cases that I have in mind. I know people from these groups, so I can put you in contact with them if you are interested.

I don't know about any commercial available product for fecal sludge solar drying. However, you can find some options in the case of sewage sludge (mostly greenhouses). In fact, solar drying in greenhouse has been applied in sewage sludge drying with quite positive outcomes.
My advice is to design your own solar treatment. You can get inspired by what has been done for sewage sludge and food products (the major applications are there).

One of my areas of research is solar drying of faecal sludge as I found a great potential on it, particularly in countries with important annual sunshine.

I am available to have a discussion with you and give you guidance. Please send me a private message if interested.

Kind regards,
Santiago

Did you install a vent pipe to get rid of the condensate? In doing a UDDT I did not find a large amount of condensate, especially enough to require a drain at the bottom. Most of the moisture is in the urine and if it is separated that takes care of the moisture and most of the odors.

Yes odours got out and it did smell. They seemed to reduce once a crust had formed on top of the sludge.

I sloped the glass from back to front, only because it seemed easy to make the still that way.

There is a balance to made. Too much ventilation and the temperature does not build up in the still , too little and the condensate runs back into the sludge and drying out process takes longer. If I was to build another, I would have a steeper glass slope so the run off was faster and have an internal drainage channel which would then collect the condensate and run out through a drain plug at the base of the unit. I would collect and bottle the condensate and sell it to Bill Gates who seems to like drinking such stuff.

You have two choices, time or temperature or a combination of the two. Heating the feces to 160F will kill all pathogens. Another option is lower temperatures for a longer time. If you have a window to the south and allow 6 months for heating and cooling the pathogens will be destroyed and dry product will be safe to use as a human fertilizer. Go to www.sanitationhealthintransition.com and under "sanitation" chapter 2 you will see a diagram that will give you the time and temperature to destroy the pathogens.

hi kevin,

not sure about the solar treatment but with the technology called aquatron i can manage to decompose the dry faecal that to without any chemical, mechanical or electrical parts. the solution is in the nature itself and the inventor of this technology is able to find it.

here the link you can check every detail: www.aquatron.se

i guess solar treatment system might create an issue during mansoon as myanmar known for high rise rainfall.

thanks,
Akshay.

Hi Steven,

This is very impressive, especially given its simplicity and the temperature logger.

Were there any odor issues? If the humidity can get out, it would seem that odors could also.

You said that condensate flowed across the under side of the glass because it was tilted. What angle was that? Was it tilted laterally or longitudinally? Was only the lower edge of the glass separate from the box to allow condensate and humid air to get out?

Has anyone ever done similar temperature logging of Unplanted Drying Beds? What about the effects of the UV?

Best wishes,
Chris Canaday

Here is a low tech piece of basic research which may be helpful. I undertook the work in my spare time whilst I was working on another project in Tanzania. The temperatures reached within the cooker were high enough to destroy Ascaris, but I'm not sure how practical solution would be in dealing with large quantities of sludge.

Dear Kevin,

Here is a presentation from Sanivation: www.susana.org/_resources/documents/defa...740-7-1488812968.pdf , in case you did not find it yet. To the best of my knowledge, Sanivation has a functional treatment facility set-up at Kakuma refugee camp in Northern Kenya. However, since they produce a biochar from the fecal sludge, their process may involve more than just solar heating. Since there are multiple Sanivation staff members on this forum, maybe they could give us all some more info?

There was also this BMFG supported group from the USA: forum.susana.org/169-production-of-bioch...har-uni-colorado-usa But, their approach seems a bit high-tech to me.

Regards
Marijn

Hi F H,

thanks for the paper.

However I am talking about dry feces and not about waste water.

And I thought more of a solution like a solar cooker. So something like this: solarcooking.org/plans/

So my idea, would be to essentially boil the feces for X minutes to break down the pathogens. Since it will have more than 100°C, I think this goal will be achieved. But I don´t know if there have been any trials with heating feces.

I hope anybody has experiences with that topic or knows a relevant research paper.

Thank You!

Dear Mr. Kevin,

Please check this link: www.bvsde.paho.org/muwww/fulltext/repind...erial/bacterial.html.

It is the paper by Polprasert, M.G.Dissanayake, and N.C.Thanh, who were, back then, the faculty members of the Environmental Engineering Division, Asian Institute of Technology, Bangkok. The title of paper is: Bacterial die-off kinetics in waste stabilization ponds

Regards,

F H Mughal

Hello,

I am looking for a solution to treat feces with solar energy in order to kill the pathogens in the feces quickly. The feces would come from UDDT toilets, but can not be composted/treated inside the toilet. The project is located in Myanmar, so therefore we have enough heat and solar power. Thats why I thought of having a central treatment facility inside the village and using a solar powered system.

By searching in the forum I came across the company "Sanivation". However, I can´t find any updated news about the progress there.

Are there any other commerically viable products with solar energy?

Thank you!
Kevin