Dear Chris

Sorry for not having spotted your questions and remarks on our post earlier. I will rush to answer them now.

1) We will be working on the final version of the cartridge later. At the moment, we are striving for a new version of the entire toilet, which will be field-tested in Nairobi in March (in cooperation with Sanergy). The smell was already no problem in the first field-tests. The little bit of energy, which we spend on a forced air-vent takes care of this. I have no doubt that the clever colleagues at EOOS and Tribecraft (a new cooperating company) will solve the problem, but you are right that it is very challenging.The idea is that people will be able to exchange cartridges themselves; exactly for the reason you mentioned.

2) You are right that in principle there are four barriers. However, the membrane is such a powerful barrier that we did not mention the biological treatment. The main function of biology in this system is to degrade the pollutants and to keep the membrane open for water.

a)+b) Please let me answer these two questions together. Electrolysis can be used for many things, not only the production of oxygen and hydrogen from water. In this system, we mainly produce chlorine in order to remove the rest of the organic matter and disinfect the water. This is important in order to remove the color from the treted water (increase acceptance and thus compliance) and to prevent re-growth. Especially Legionella could be critical, but also other pathogens could move backwards through the system. In the present system, we automatically dose chlorine when there is not enough solar energy for electrolysis. This may seem ‘too much’, but for a long time to come, we will in reality do field-experiments involving real people. How it will look in a few years when we hope for the system to be multiplied depends a lot of the experience gathered in the field and in the lab.

Chlorine in moderate amounts is no problem for the biological reactor. It will immediately be eaten up by the large amounts of organic matter in the tank. We have more problems of securing the little bit of excess chlorine in the clean water tank necessary for controlling the biofilms in the piping (in your own drinking water system, biofilms are probably controlled the same way).

c) The membrane is very reliable if not mechanically damaged. Since we have no long-time experience in the field, we cannot quantify the risk of such damages. Your idea of a warning system is very good. I am not quite sure that it is necessary; the water would probably get turbid if the membrane would get damaged. We will however keep your idea in mind.

d) We are testing your idea of biological activity in the clean water tank, albeit in a less spectacular way, without plants and without fish. It could work the way you suggest and at least reduce the requirements for electrolysis. However, at the moment, we work more concentrated on reducing the energy requirements for electrolysis. I do like your wild idea, but since we are working under extreme time constraints, they will have to wait a little - perhaps somebody else could test is?

The next version comes with a hand rail (the first working model had two).
We will inform about the next generation blue diversion toilet towards the end of March when we have done the first tests in Nairobi.

Kind regards and thanks again for all your great comments and questions

Tove

Dear Everyone,

For your info, that Tove took part on the second expert chat with a group of BMGF grantees on September 12.

She took this opportunity to present the current state of the project and to answer to several project-related questions by the moderators and participants of the chat.
A video of the expert chat is available on youtube – please find it under the link below, starting exactly at Tove’s presentation. Unfortunately some sound cross-overs occurred.


Find a pdf of her presentation here:
forum.susana.org/forum/categories/139-ge...te-sept-12-2013#5624

Additionally to the information Tove and Bernhard have posted already in this thread, the following project news and questions that were raised during the chat might be interesting for you, too.

The team around Tove at Eawag in Switzerland is developing a dry source separation toilet with on-site ultrafiltration water recovery. It collaborates with EOOS, an Austrian designing company and Makarere University in Uganda. A shared toilet for 2 families was developed, for which resources are recovered at a larger scale in a Resource Recovery Plant (for 175 families). Also a logistic concept has been established for transporting dried faeces and undiluted urine from the shared toilets to the Resource Recovery Plant. From the urine, fertiliser is recovered at expense of energy generated from faeces.

With regard to the toilet design: to increase hygiene and comfort the toilet can be flushed. Urine and the flush water is not mixed but separated by a technical device. Water can be used for hand-washing as well as anal cleansing. The water is recovered on-site in the water wall of the toilet by an ultrafiltration membrane treatment tank which functions exclusively by gravity – a method developed by Eawag for drinking water production. The polluted water is pumped up with a foot pump and the ultrafiltration membrane is kept open by higher organisms grazing on the membrane so one doesn’t have to maintain it. The water comes out of the membrane virus- and bacteria-free but slightly coloured. Electrolysis then removes the colour and at the same time the traces of organic matter and produces chlorine for disinfection.

Very early in the process of designing the UDDT, they interviewed potential users in Kampala, Uganda, on their attitude towards the toilet. The general feedback was positive; the interviewed person especially liked the convenience of a water tab and the flush button.

The maintenance interface is very important so that the people collecting the urine and faeces twice a week will not be sick. The toilet can be opened only if the rim is pulled. If the rim is pulled the faeces container is sealed automatically and the urine can be pumped from the bottom of the container. The container can also be removed by the users themselves in case they are having a party with many guests, for example.

Field testing was started in spring 2013 in Kampala, Uganda, in cooperation with Makarere University. The feedback by the users was again positive, but many details needed improvement. The toilet pan looked slightly different to the initial design: People open the faeces lid with the foot and when they use the shower or flush afterwards this lid will close automatically and only the front part is flushed. This is an advantage as both washer as well as wipers can use the toilet.

The business model is set up as a rent-a-toilet model, because very few people will be able to buy the toilet. Also, they can be placed in any superstructure.
A business case in Uganda was set to see whether the cost of using the toilet of 5 cents per person per day was realistic. It is a challenge, but because urine and faeces are diverted it could be possible due to the income of selling the recovered nutrients as fertilisers. Also, it is important that there will be a profit for the entrepreneur who runs the business. Operational costs are relatively high; therefore it is necessary that funding for local maintenance is available.

Question 1: Is the membrane a very expensive unit? And what is it?
Answer 1: These are the normal membranes, which one would also use for drinking water production in a normal drinking water plant in Europe. They used to be expensive but prices have been falling a lot in the last time. 20-25 % of the construction costs of the toilet will be for the membrane but at the same time it will last for 10 years. The important thing is that the membrane will not have to be maintained (cleaning not needed).

Question 2: When you say people liked the toilet, how many people did you talk to?
Answer 2: 400 people were using the toilet, some of them only once and 6 families were using it for 2 weeks (3 x 2 families, each 2 weeks). About 1500 people were being interviewed, also about the willingness to pay, which was quite high; about as high as it needs to be in order for the toilet to be implemented. Eawag financed an additional social science study that will look into all the interviews that have been made. There will be a report, when all responses have been analysed.

Question 3: Might the toilets not be too advanced for the context in Uganda? People might be hesitant to use it. And do you know what the costs will be to set the toilet up in that local context?
Answer 3: Target costs are 500 USD per toilet and a lifetime of 10 years. The project team is currently not only improving on the design but also on the technology so that target costs can actually be reached. A mechanical engineer is working on this now and the project team hopes that they will soon get an additional grant so that they can really go into the reengineering which will need professionals. At the moment there are still too many parts.

Question 4: With regard to the business model and costs: In the current phase you are also developing a partnership with other projects for the treatment for the urine and the faeces. Do you already have any indications how feasible these end product sells and how to integrate this into the 1.3 resource recovery plant costs? Can fit with the current technologies you are looking at. And regarding the service fee of 5 cents per person?
Answer 4: They think that this is feasible. In the business plan, reasonable cost targets for the technology at the Resource Recovery Plant was set, including typical costs for operation and maintenance. At the moment, only pilot plants exist, the team used normal scaling of costs from pilot plants to industrial equipment in order to calculate the costs for a number of different technologies. There were a number of technologies that could potentially fit the cost targets. At Eawag, technologies for urine treatment is developed, whereas faeces treatment is done by other grantees (e.g. Climate Foundation). In both cases, the team is optimistic that financially viable technology can be developed. Existing technologies like anaerobic digestion of feces would also fit well together with the urine treatment at Eawag (for more information: www.eawag.ch/vuna).
For the logistics they did a model study and it showed that they could get down to around 1 cent per person per day for collection and transport. And on all of these prices and the business model they are now working on. In phase 2, they got additional funding from SDC (the Swiss Agency for Development and Cooperation) in order to set up a really robust business model. There is one part of the toilet where they have problems to get costs rapidly down and that is electrolysis. But there are so many electrolysis experts in the RTTC grant who could possibly help.

Greetings from seecon,
Naomi

Dear Tove

Thank you very much for your participating in this interesting expert chat. (for more information about the expert chat, please see here: forum.susana.org/forum/categories/139-ge...te-sept-12-2013#5624)

I really hope we can fix the sound so as it does not seem anymore that we talk at the same time. And I can only confirm that we were actually very disciplined!

In the meantime, let me ask some further questions for which was no room during the 1 hour chat:

Compared to the other presenters, you are already qui in advance concerning the aspic of reusing not only the water, but also the nutrients.
-> Can you tell us more about the technologies your are looking at for the recovery and reuse of urine and faces?

Moreover, in the business model presented, you mention and end-product price and indicated that this is has been calculated on market prices.
-> Can you give us further information regarding how you measured this market prices. I.e. where this local prices from the testing sites? And based on what: nutrient/energy equivalents?
-> Have you already been thinking of how to accessing the local nutrient market to achieve the target revenue prices or did you already establish a partnership to think about this "piece of the puzzle" (e.g. wholesalers, other, …)?

Best regards
Dorothee

Dear Tove,

Thank you for your helpful response.

1) I look forward to seeing the new version of the feces cartridge. This is a big challenge to make the feces disappear and control smell without cover material.

With respect to volumes and maintenance frequency, we also have to remember that people will have parties from time to time. Could the users have extra cartridges on hand and change them themselves when needed?

(You may want to dust the interior of the empty cartridges with finished fecal compost to introduce beneficial decomposer microbes, plus it may be beneficial to add another dusting of it after each use, for the same inoculation and to help control smell.)

2) Please allow me to retract my disparaging comment about the use of recycled wash water. This is one of the great strengths of your design, which allows it to stand alone anywhere, without constantly adding more water or dealing with effluent.
I realize that there is biological treatment given by the biofilm upstream of the filtering membrane. So you currently have a 4-barrier system (not just 3 as stated on www.diversionsanitation.com/): biofilm, artificial membrane, electrolysis, and chlorine. I would suggest that one reliable barrier should be enough and two would be great: the biological filter and the artificial membrane.
a. I see no reason for the chlorine, if the membrane reliably keeps all microbes and viruses out. The chlorine would not be good for the biofilter at all, would represent an added expense, and could from time to time run out or be neglected.
b. Electrolysis of water, per se, is the splitting of H2O by electricity into H2 and O2, but you are obviously doing something different. Please give us more info on this. Where does the electricity come from? Why is this necessary?
c. How reliable and long-lasting is the membrane? Does it have no seams with bigger holes from the needles? A stable, non-reactive, inorganic dye, with molecules or fragments the size of viruses, could be placed in the treatment unit to warn users when the membrane has become defective and needs replacement.
d. I suggest expanding the biological filtration to the clean water holding tank below, by converting it into an aquarium, with a clear panel in front of it and adding lots of aquatic plants and a couple of small, hardy fish. The plants would help to consume the nutrients that would get through the membrane, plus would foster the growth of beneficial, cleansing microbes.
www.fao.org/docrep/003/x6862e/X6862E11.htm
www.ehow.com/info_7931670_aquatic-plants-clean-water.html
www.drsfostersmith.com/pic/article.cfm?d...y=327&articleid=2309
The fish would eat the algae as it develops, add life and fun to the toilet, and would serve as a “canary in the goldmine”. (If the water is good enough for that fish, it must be good enough for my bum and hands.) By the way, for years now we have a fish in the rainwater tank for handwashing at our UDDT (mainly to eat mosquito larvae) and people really enjoy seeing him there, plus there are no known diseases that pass from fish to people during handwashing.
The aquarium would have a little refuge of water for the fish at the bottom, which cannot be pumped dry. I know this is a wild idea, but it would improve water quality and user acceptance, at a lower cost than electrolysis and chlorine.



Note from the attached drawing that I am also suggesting putting some optional poles for people to hold on to, especially thinking of the handicapped, the old and frail, and the Westerners.

Please keep us informed of the project’s advances. If I can be of any help, please do not hesitate to let me know.

Best wishes,
Chris Canaday

Note by moderator (EvM): Tove's post was moved into this thread to stay with the other posts about this project. The questions that Chris Canaday had asked to Tove, as a result of watching the recording of the expert chat, are here:
forum.susana.org/forum/categories/139-ge...te-sept-12-2013#5637


Hi Chris

Thanks for your questions, which are all very relevant. I will answer them as well as I can. The technical problems with people talking at the same time is an artefact from processing of the tapes. I hope it will be corrected soon. In reality, we were all very disciplined!

1) First of all: The feces container will not look like this. It is a simple model showing the principle we are aiming for. We are aware of all the aspects, you are mentioning and trying to find solutions (reduce visibility of feces; make the container large enough without increasing the size of the toilet; give feedback when the container is full). The container will be designed for containing around 4-5 days of feces from 10 people, i.e. roughly 16 kg of feces (+ toilet paper). We plan for an emptying service twice a week, meaning that the container will normally not be full and thus less heavy.

2) We do have biological treatment in the water wall. The water, which will be chlorinated in the electrolysis process has already been biologically treated and ultrafiltrated. Chlorination is meant as the last disinfection step similar to what is done in water distribution networks in order to prevent re-growth of pathogens. We do not expect recycling to increase the risk of resistence, because the microorganisms will not pass the ultrafiltration unit. The critical issue is biofilms and we will keep an eye on them.

3) We chose a principle of water recycling in order to set up a system, which has a good chance of providing hygiene in a dense urban slum. With no emissions to the environment, we have a high degree of containment of fecal pathogens. Nobody has to buy water (river water will be good enough to replace any lost water in the system) and still there will be water enough for flushing, anal hygiene and hand washing.

4) We are reengineering the blue diversion toilet for the next field test in February-March 2014 and already then it will look quite different. In the short development time, which we have had available (from July 2011), it was not possible to get everything perfect from the beginning - and it will probably not be in February either.

I hope that this information is suitable to answer your questions. And I would like to thank Arno Rosmarin and the other organizers for setting up the webinar, which I enjoyed very much. It was great to hear the news from the colleagues.

Dear Bernhard, Tove and team,

You will be pleased to know that your toilet featured on the news in the US yesterday! It has such an attractive design, I think this makes it easier for journalists to pick up on it...

The title of the article is "Gates Foundation offers locals opportunity to learn", and it comes with a nice 4 minute video which includes your toilet:

www.king5.com/news/cities/seattle/Gates-...learn-213190711.html

The kids are out of school for the summer and many parents are looking for ways to keep them occupied. The Bill and Melinda Gates Foundation Visitor Center gives families an opportunity to learn what people around the world face on a daily basis.

"Whatever the conditions of people's lives, wherever they live, however they live, they share the same hopes, the same dreams as you and I," Melinda Gates said.

Millions around the world do not have access to clean drinking water and billions do not have safe sanitation facilities.

I saw it on Twitter (@gatespoverty).
It's always a good thing to get this topic (sanitation) into the mainstream news to raise awareness.

Regards,
Elisabeth

It was nice that you could visit our first field tests in Uganda!

I agree that Gravity Driven Membrane (GDM) filtration is an excellent technology for drinking water production. I very much hope that this technology will soon come to maturity and become wide-spread - my colleagues are working hard on this. What we try to do with the blue diversion technology is to solve the problem of sanitation in a comprehensive way. We are not only providing clean water for personal hygiene (hand washing and anal cleansing); we are also treating the higly contaminated wastewater, which arises from these activities. We can do this without much energy because urine, feces and water are not mixed in the system. Furthermore, we hope that our system promotes actual hand washing (and not only the theoretical possibility) by offering clean water directly on-site. I do agree that the system is too complex at the moment. What we are testing now is whether people like the services from blue diversion. If we obtain the necessary funding, we hope to be able to start the technology-simnplifying process in June this year.

gitum wrote: Before reading the comments and watching the videos, the first question came to my mind was how you were dealing with the fouling problem of ultrafiltration membrane. I assume it is a dead end filtration and hence it would be fouled in a short time. It really impressed me to hear that your system has minimum 10 years life time.

I have by now seen the system here in Uganda, and as expected it is based on this technology:
www.eawag.ch/forschung/eng/gruppen/gdm/index_EN
(with an added aeration pump and electric oxidation as polishing post treatment).

Personally I think such an advanced system should be better used to treat drinking water (here in Uganda), than recycling small amounts of wash water that is abundantly available anyways... but that is another discussion

Dear Tove,

thank you very much for the further information. I am looking forward to follow the upcoming news from March 2014.

Best Regards,

Gökce

Dear Gökce,

thank you very much for your nice remarks on our project. I am afraid that we have not had time to update our homepage on the urine treatment methods, which we are working on in the RTTC project. However, they are derived from the main Vuna process: Stabilization of urine followed by evaporation of water (www.eawag.ch/vuna). We stabilize with partial nitrification and use the RTTC as an opportunity to work on a reduction of the size of the nitrification reactor. The Vuna evaporation is a classical distillation with energy recovery. In a combined RTTC-Vuna effort, we work on heat-driven evaporation in order to become less dependent on electricity. For feces treatment, we rely on other RTTC groups working on different pyrolysis and combustion methods. We will use the heat generated in these processes for evaporating the urine. The results of the work will be presented in March 2014.

Kind regards
Tove

Dear Bernhard and Tove,

it is very interesting and impressive to see the technologies like ultrafiltration and electrolysis applied in such a feasible and a practical way.

Before reading the comments and watching the videos, the first question came to my mind was how you were dealing with the fouling problem of ultrafiltration membrane. I assume it is a dead end filtration and hence it would be fouled in a short time. It really impressed me to hear that your system has minimum 10 years life time.

I know the focus of the project is user interface but I still want to ask which processes are used to produce fertilizer? I saw you applied cost analysis and I accept you applied it according to the selected treatment options and their end-products. Do you apply only urine as fertilizer or do you also benefit from faeces? I saw in the previous comments that you were considering different treatment options for faeces and I wonder which one have you came up with? It would be also great to hear whether you apply a process to urine or not.

Thank you very much in advance.

Regards,

Gökce

+++++++++++++
Note by moderator (EvM): I just came across this nice 1-minute video clip about the project; it is a bit old (from August 2012), but so professionally done that I thought it should be shared:
1-minute video about the concept (produced just after the Reinvent the Toilet Fair in Seattle, August 2012):

We are happy to announce that we brought our toilet prototype to Uganda, Africa for user testing.
The feedback we got so far is very positive but we also learned some valuable lessons that will help us to further improve the design.