The experimental set-up of the plasma gasifier at the TU Delft was shown on German television and dubbed as the 'the toilet of the future'.

www.wdr.de/tv/quarks/sendungsbeitraege/2...ette_der_zukunft.jsp


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Note by moderator (EvM) on 15 Aug. 2013: We are closing the discussion in this thread which concerns their RTTC Round 1 grant. Please continue the discussion in this thread on their RTTC Round 2 grant: forum.susana.org/forum/categories/98-res...d-india-rttc-round-2

Dear Gerwin,
Thanks for your reply and the answers to my questions.
I am looking forward to your future results and lessons from the adaptation to the Indian slum context that you are targeting with the plasma gasifier technology.

Please keep us updated on the progress of your work!
Best regards,
Kim

Dear Kim Andersson,

Thanks for your positive reply!
Regarding your questions about the system that is introduced above, I have to inform you that this was just one of the proposals we have been working on. We're likely rejecting urine diversion as well as the technologies described for drying and water treatment.
Anyway, I'll try to answer your questions for as much as it's still relevant.

- What are the greatest challenges so far in your research work?
Integration of all systems. Closing energy & mass balances. As well as adapting technology to context (in our case, urban slums in India)

- What do you think will be the appropriate scale(-s) of your process system?
Our plasma gasifier caters the waste of at least 2,000 people every day. This could possible be scaled down in the future.

- Will the system be self-sufficient in terms of energy, considering the electricity generation from the fuel cells?
The plasma gasifier generates sufficient energy to sustain itself and possibly a surplus that can used for purposes that could benefit the users or community.

- For the processing of fecal matter: What will the rest product from plasma gasifier unit look like. Will it be possible to reuse nutrients from this step?
A significant amount of P-rich ash that can be used as an enhancement for fertilizers.

- For the processing of urine: The struvite production has high potential to recover phosphorus, but how about other nutrients? Will it be possible to recover the nutrients captured in the filtration process in your White line?
K,N,S remain in the water and can be used for fertigation purposes

We are currently working on a more low-tech proposal (sand filter combined with UV) and might share our findings on the forum at a later stage.

Kind regards,
Gerwin

Dear all,

Many thanks, to all researchers sharing information about yourselves and your innovative research project. You have really been successful setting-up a multi-disciplinary consortium of researchers, which will be valuable to face the different challenges you will face. Maybe you can answer some of the question that I had when reading about your project:
- What are the greatest challenges so far in your research work?
- What do you think will be the appropriate scale(-s) of your process system?
- Will the system be self-sufficient in terms of energy, considering the electricity generation from the fuel cells?
- For the processing of fecal matter: What will the rest product from plasma gasifier unit look like. Will it be possible to reuse nutrients from this step?
- For the processing of urine: The struvite production has high potential to recover phosphorus, but how about other nutrients? Will it be possible to recover the nutrients captured in the filtration process in your White line?

Thanks and looking forward to hear more about your work!
Best regards,
Kim A.

Note by moderator (EvM, 23 May 2013). For clarification from Gerwin Jansen about this post: "He was one of our graduate students that made a proposal for waste and water processing system. He used the Susana forum to get feedback on his work. Meanwhile our graduate student quit and our current system turned out to be different than his proposal."[/color]

Hello everybody,

I'm new here so I will start by introducing myself. I'm a soon to be MSc Industrial Designer at Delft University of Technology, the Netherlands. And I would like to share what I've been doing for the past months. As you maybe be aware or not, TUDelft is involved in the Reinvent the Toilet Challenge, and as a master student I have been developing a toilet system, which main objective is to remove water from solids and dry them in order to meet plasma requirements (Technology proposed by TUDelft for the Bill & Melinda Gates Fundation). To do so, faeces are separated from urine by means of a diverting squatting toilet. The development of two diverting toilets (for children and adults), user research, prototyping and testing was carried out in India.





After processing, faeces are fed into a microwave plasma gasifier to produce syngas. This gas is used to produce electricity with the help of solid oxide fuel cells (SOFC). Processing of faeces involves the screening of unwanted materials (eg toilet paper), wastewater (faeces and flush water) conditioning for an easier separation of solids from liquids, and the use of gravity and compression forces to dewater faecal matter. Finally, all remaining solids are exposed to a couple of heat sources; the sun & plasma technology. In a parallel process, urine is mixed with Mg (Magnesium) to produce struvite. Last but not least, both processes expel wastewater that is directed through a series of filters (gravel, activated charcoal, crushed limestone, and reverse osmosis) and turned into clean water.

Bellow you can find a more detailed description about this toilet system, and a link
to a video (VIMEO) that illustrates the system's main characteristics.

Thank you for reading this, and bear in mind that this is still a work in progress so please share your thoughts, suggestions and questions.

Daniel P.


---Toilet System for Waste Separation and Dewaterization---









Saffron Line

This process line has the objective to extract most of the water content in faeces, and to deliver small pellets for dehydration. These pellets, once dehydrated, can be fed into the plasma gasifier unit. This line starts at a screen mechanism. Here all alien objects can be screened and rejected, and virtually only faeces go through to the next step; conditioning. In this process a polymer is dosed gradually at in to the wastewater. The polymer is applied in the first chamber, where in a rapid-mix the mixing shaft will help to disperse the polymer and achieve coagulation. After coagulation, flocks will start to form. Flocculation occurs in the second chamber. The mixing shaft rotates at lower rpm than in the first one. This allows flocks to form and prepare the mix for the step to follow.

With the flocks ready, the mix can be now thickened. This process uses gravity and a belt to separate water from solids. Water is then directed to the “White Line”, and solids accumulate on top of the mesh. Unlike conventional belt press systems, here the belt is fixed and a mechanical plow pushes the accumulated solids to an opening on the far end of the belt. This mechanism composed of different blades spreads solids evenly across the belt, and at the same time separates solids from the belt to allow more water to flow through.

Eventually, the solids are pushed and dropped into a screw. Second to last, the screw is the step where solids are pressed to form pellets. The screw is a low rpm mechanism, composed of a screw and housing that gradually removes more water. Solids exit through a blade that forms pellets for the dehydration step. Finally, solids (pellets) are dropped into a cart. Here the solids are placed on a tray, and when full the cart's transparent lid is shut. The cart can now be moved by an operator to a different area where the process of dehydration occurs.

First, the cart can is plugged to a heat source. The microwave plasma and SOFC generate heat when operating, thus the need for heat dissipators together with a heat recovery system. Heat recovered can be redirected and feed into a mini-grid, where the cart can use it to dry solids. Additionally, heat from the sun can be used to accelerate the dehydration process. This method was proven effective empirically, considering that India has a capacity of 4.5 kWh p.s.m. The heat mini-grid is placed under the sun and oriented so the cart can face the sun for the most part of the day. When dry, the tray containing the pellets is then removed by an operator and taken to the plasma feeder.

Green Line

The process of precipitating struvite from urine starts in the toilet slab, where urine goes through a small device that works as a sealant for odors. This device uses a chemical agent that has a lower density than water, which will always stay above the urine.

The efficiency of struvite precipitation is dependent on how diluted is urine. This device could reduce significantly the use of water, but users understanding and acceptance is essential. Urine then is directed to a storage tank where it is stored with the sole purpose to increase urea and pH levels. This helps struvite precipitation to be more effective. After storage, with a pH value around 9, urine is sent to a conditioner tank, where magnesium is added to form struvite.

Mg is added gradually with a dispenser and is controlled by a flow-meter. Once Mg and urine are mixed the flow is directed to a precipitation tank. This tank is composed by a frame and a cloth. The frame holds the cloth, which allows water to flow freely, but holds back the struvite flocks. Eventually the cloth will hold enough struvite and will have to be replaced. The cloth that was removed is then left to dry at a temperature of less than 50º. A less harmful liquid for the environment (compared to raw urine) is the byproduct of the struvite precipitation, and it is directed to the “White Line” for further filtering.

White Line

White line is the process of recovering and filtering wastewater, which comes primarily from two sources, after struvite precipitation (Green Line) and from the thickening process (Saffron Line). Water goes through two different stages. The fist stage pre-filters water, and consists on large particle removal by means of granular filtration. Gravel is used for this purpose. The horizontal setting of this stage uses three sizes of gravel (16-30mm; 8-16mm; 4-8mm), where the gravel size is reduced towards the end of the filter. Once at the far end of the filter water is pumped to a storage tank. And from the storage tank the water is pumped to the second and final stage; reverse osmosis. The second stage is composed of four filters, similar to what is often used in households for water purification. The first filter is for sedimentation purposes. A 5 micron filter is used to trap and accumulate suspended solids. Next, a crushed lime filter is used to neutralize pH, chemical precipitation, and odor control. The third is an granular activated carbon (GAC) filter. GAC reduces odors and bad taste caused by chemicals, such as chlorine. It is effective at absorbing organic pollutants, and adds natural minerals to the water. Finally, the last filter is a reverse osmosis membrane of 1/1000 of a micron that removes and filters contaminants. If any, waste water is diverted to the beginning of the process line. Filtered water is then directed to a final storage tank, where it can be re-used for several purposes, such as cleansing and pour flush.

Hello!

My name is Miguel Melgarejo, I am part of the design team from the TU Delft working for the Reinvent the Toilet Challenge. We are working with the plasma gasification technologies and it's possible applications in dense urban Indian slums.

One of the many major challenges of introducing a radically new sanitation system is how to communicate it and engage with the target users/community. Here at the TU Delft we are exploring different possibilities for our system.

Our initial research showed that our target users have access to diverse media channels and are highly influenced by them. That's why we are looking into developing a brand that taps more into their aspirational values rather than just presenting it as a sanitation solution. Right now we are looking further into the branding of the system, it would be good to see who else is looking into this area!

Communication-wise we are looking into new possible channels such as cell phones and smartphones (which are penetrating slowly in urban slum communities). Connecting with users through their cell phones could bring more reliable statistics and even possible fee-payment platforms.

You can see attached some images that summarize our initial ideas in this areas. It would be great to hear and connect with people that are also looking in this areas to exchange some ideas and experiences.

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Note by moderators: This post was made by a former user with the login name miguelmelgarejo who is no longer a member of this discussion forum.

Who am I?
I'm a member of the design team of Delft University of Technology, one of the participants in the 'Reinvent the Toilet' challenge. My role within our team is to integrate the fecal processing technology (we use plasma gasification) and the toilet interface. So my focus will mainly be on the diverting toilet, as well as collection and conveyance of the different streams, and drying of the feces.

In response to Bernard's call for designers, I'd like to share what we have been working on at Delft University of Technology.

One of our team members has made a prototype for a diverting squat toilet for adults as well as one for children (4-6 yrs old). Dimensions are based on anthropometric data he collected himself in the slums in New Delhi. Maybe it's good to mention that involving children is much easier (especially when making the measurements part of a game) than measuring adults, women in particular. Anyway, the collected data has been crosschecked with data from Chakrabarti (1997).

The fiberglass prototypes are made by a manufacturer in Bangalore and evaluated with the people in India. This has shown that the basic dimensions of both the adult and children toilet are adequate. Also their opinions about the prototypes were collected. What they liked most is that the cleansing area is bigger. Introducing a 3rd hole for collection of anal cleansing water is not desired because they are not willing to move backwards to position themselves above this 3rd hole. Finally, the understanding among children was evaluated since a diverting toilet is new to most of them. When asked to sit on the toilet, all children took the right squatting position. Apparently the different features of the toilet (foot rests, size of the holes and the splashing screen in the front) give them enough clues to understand what the required orientation.

Some things to consider when designing an adult unisex toilet:
- Female users will have more difficulty directing the urine stream towards the urine receptacle
- The placement of the diverting element possibly requires different positioning for female users
- What percentile will you focus on? (many toilets are designed for males in the 75th - 95th percentile, which results in a toilet that is too wide for women and smaller men)

Regarding children toilets, our prototype may not suffice children older than 6 because they are too big. This means that multiple versions of children toilets are required.

Since there will not be a on-size-fits all solution for UDDT's, one of the things that we will be looking into is how to connect the different toilet versions (range of sizes, squatting toilet, Western toilet) to our system. Ideally, this is a simple plug-and-play system, which makes it replicable all around the world.

Cheerio,
Gerwin

Note by moderator (EvM) on 14 August 2013: the thread below concerns a grant by TU Delft under the Reinvent the Toilet Challenge (RTTC) Round 1 which is now completed.

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As this is the first blog post of the Delft team for Reinvent the Toilet, I’ll give you a brief introduction into our way of working and targets. We’re a combination of designers, engineers and scientists developing a new sanitation system for its context (South Africa/India) while researching and integrating the technology. In Holland, we’re researching the production of hydrogen by plasma gasification of human waste, while in India and South Africa we’re doing context research and testing prototypes on how to use the technology in real life.

On the picture you can see a brief preview of our fair exhibits, the two user interfaces and integrated technology. They’re just a preview, not the real thing yet! At the moment, we’re still working hard on the mock-ups, because they only recently came back from user testing in Durban and Delhi.
India: This technology allows us to have mobile, processing toilets. In India we use this to make one stationary block of toilets in a legal slum, which is combined with mobile toilets for peak hours and illegal slums, to avoid open defecation and provide for the harder to reach target groups. The user interface splits waste streams and pre-dries the solid waste to prepare it for processing. Quicksand in Delhi helped us out with office space and helpful connections for the context research and user testing.
South Africa: This is a household application for the technology. The pedestal splits the waste streams without any effort for the user, and closes the vault to prevent flies and odors. The toilet pre-dries the solid waste for processing, and to avoid transporting water (at the moment, the waste still has to be transported to a MMPP close by). Our student team got a lot of assistance and feedback from prof. Buckley and his team during the user testing in Durban, for which we are extremely thankful!
Integrated gasification technology: We use microwaves to generate a plasma, which gasifies the dried particles of human waste efficiently. The syngas produced is transformed to electricity by a solid oxide fuel cell. The picture above shows the lab setup, on the fair we’ll present a mock-up of the integrated technology, with as many off the shelf components as possible, to make it easy to produce and maintain locally.

We’re very much looking forward to meeting the other teams in Seattle, and comparing results. Maybe some of the other teams can give a preview as well?