SuSanA - Forum

Bioelectric Toilets for Waste Treatment and Energy Production (University of Colorado, USA) - by: bioelectric

Fri, 24 May 2013 17:34:51 +0000

Dear All,
I would like to introduce our technology and systems that are funded by the Bill & Melinda Gates Foundation. I am an associate professor at University of Colorado, USA, and we are focusing on developing bioelectric toilets that can directly convert human waste and other waste materials to electricity and other chemicals for household and other uses. We have been working on this platform technology for several years and are leading the R&D work in low-cost modular system development. I hope you find the information below interesting, and please feel free to contact me at bioelectric2013 at gmail.com or jason.ren at colorado.edu for any questions and collaboration opportunities.

Title of grant: Direct Electricity from Fecal Sludge in Bioelectric Systems
Subtitle (more descriptive title): Innovative modular bioelectric toilets for on site human and animal waste treatment, electricity generation, and chemical production and utilization.
Name of lead organization: University of Colorado
Primary contact at lead organization: Zhiyong “Jason” Ren
Grantee location: Boulder, Colorado
Developing country where the research is being tested: Uganda, and a few other countries in discussion
Start and end date: November 2011
Grant type: Grand Challenges Explorations, Round 7 (GCE R7)
Research or implementation partners: Water for People, Universities in several Countries in Africa

Goal(s): The goal of this project is to develop a low cost and easy-to-operate bioelectric reactor that uses microbes to break down waste and convert it to usable electricity and chemicals. This technology could provide a self-sustainable solution for communities in need of both sanitary waste disposal and an energy supply.

Activities or key research components:
We focus on developing low cost and easy-to-operate bioelectric toilets to treat fecal sludge and directly convert waste to usable electric energy and chemicals. The principle and operation of bioelectric toilets are relatively simple, but it represents a completely new method for high quality energy and chemical recovery from waste. In the reactor anode chamber, microorganisms degrade fecal sludge as their substrate and transfer electrons to the anode during anaerobic respiration. The electrons then flow to the cathode through external circuits, where they are harvested for electricity generation or chemical production. The electrodes can be low-cost and locally available materials. Indigenous bacteria can be used as catalysts on both the anode and air-cathode to reduce cost and promote sludge treatment.

Compared to current sludge processing technologies, the bioelectric toilet has several advantages that are suitable for onsite application in urban poor communities:
1. Our lab and field tests showed that the bioelectric toilet stabilizes and degrades >80% of fecal waste within a few days. Odor generating ammonia was removed by >75% in the same period. Reactor design shows that a 3-5 m3 reactor can sustainably handle the waste produced by a 100 people community.
2. The toilet doesn’t need any energy input except occasional manual mixing, so the electricity produced can be directly used by the community. Our prototype reactor produced 8 W/m3 electricity in the lab, and our field demonstration showed LED lights was powered by the toilet.
3. Experimental results showed that microbial communities were resilient to the variations of sludge loadings and environmental condition changes. Compared to the reduced performance of anaerobic digestion at low temperature, our system can keep its performance at even 4 °C.
4. The requirements of operation and maintenance of an established toilet can be minimal, as the microbial activity will be self-sustained and the sludge volume will be reduced significantly. The system can also be easily converted to an anaerobic digester if needed.

Links, further readings, etc:
Our group at University of Colorado has a good track record on bioelectric system development. Since 2010, we have published more than 20 journal articles and filed 2 patent disclosures, and we have obtained more than $2 million dollars in funding support from the Bill & Melinda Gates Foundation, National Science Foundation, Department of Defense, Environmental Protection Agency, and private sponsors. Our findings were reported by more than 200 media, including National Public Radio, ABC News, Science Daily, Scientific American, Discovery News, C&EN News, etc. For more information, please visit the following websites:

1. NPR report at Reinvent the Toilet Fair: www.npr.org/player/v2/mediaPlayer.html?a...4028&m=158887964
2. ABC-7 News interviews about the Poop-to-Power project with Denver Zoo. www.thedenverchannel.com/news/26211364/detail.html
www.thedenverchannel.com/news/18753218/detail.html
3. Zhiyong (Jason) Ren Faculty Website (moving to Univ, of Colorado at Boulder as an Associate Professor in August, 2013)
carbon.ucdenver.edu/~jren/research.html

Re: Energy recovery & waste treatment with floating biodigesters (Tonle Sap Lake, Cambodia - LLEE) - by: robhughes

Fri, 24 May 2013 06:38:29 +0000

Thanks Julius and Gökce,
Yes external damage is a key issue with the plastic-style digesters, so we have been trying different materials such as more durable fibre-reinforced plastic, as well as protection options (eg against UV damage). We're also currently using modified HDPE water tanks.

Julius I'm not sure rotation around the axis would help mix very much unless there were large seams etc? Also would need to consider gas offtake.

We're also looking at using the bioslurry in aquaculture ponds at our test site and land-based sites, however on the lake itself direct output to fairly open fishcages is more likely. This is already done with the manure, so essentially we're adding a stage to reduce pathogens and extract energy. We're also working on floating gardens and planned to have these also part of an integrated system producing pigs, fish, vegetables, and biogas - basic versions are operating, but still need improvement. Gökce we've tried to encourage climbing & small shrubs eg beans, tomatoes, gourds, eggplants etc - so there is separation between the slurry application and the produce itself.

The temperature in the lake water is typically around 26-33 degrees, so fairly stable. Due to this, thermal transmission in water, and the simple/low-cost nature of materials involved we're only going to be able to achieve mesophilic biodigestion. The first round of systems are achieving 2-log pathogen reduction, which we can hopefully improve with some modifications.

We're still collecting data on the gas production - but it seems to be around 300L biogas daily average for a 500L system (say with 2 pigs - around 6kg/day = 13L bioslurry). We've been very happy in most cases with the amount of biogas being produced and used by people with small systems and few animals. Our next round of experiments should give us a better idea of the potential with human waste and water hyacinth. Of course the gas production by human waste will be less than with pigs due to the quantities, and we're keen to discover if we can supplement the feed to make it feasible without animals.

Cheers,
Rob

Re: Energy recovery & waste treatment with floating biodigesters (Tonle Sap Lake, Cambodia - LLEE) - by: gitum

Thu, 23 May 2013 18:53:26 +0000

Dear Rob,

I would like to ask you couple of questions regarding your innovative work.

How much gas is produced daily and for which purpose do Tonle Sap Lake communities prefer to benefit from the produced gas (for cooking or electricity production)?

What is the average temperature of the water? Do you achieve mesophilic or psychrophilic conditions and how is the pathogen removal efficiency? What is the amount of digested sludge that you remove and how frequently you do it? As I understand, you use the digested sludge in floating gardens. What kind of plants have you selected for these gardens?

Thank you in advance.

Regards,

Gökce

Re: Toilet System for Waste Separation and Dewaterization (TU Delft, The Netherlands) - by: jansengerwin

Thu, 23 May 2013 16:31:01 +0000

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

Re: Energy recovery & waste treatment with floating biodigesters (Tonle Sap Lake, Cambodia - LLEE) - by: JKMakowka

Thu, 23 May 2013 12:25:28 +0000

Ahh, interesting.

I recently looked into floating plastic-bag biodigestors as that seemed like a great way to avoid the (apparently in Uganda significant) problems with external damage to the plastic tube which is caused (by anecdotal evidence) through playing children & rodents (and probably other forms of neglect and misuse).
However except for a few short paragraphs and pictures, it was impossible to find good examples of such a design.

Contrary to what you are proposing, it was my idea however to integrate them with aquaculture ponds, with the effluent directly fertilizing the micro-algae growth to feed tilapia.
As a beneficial side-effect the surface of the digester would probably be a good substrate to facilitate the surface growth of the tilapia preferred feed algae (that normally grow on the surface of stones and water plants etc.) and provide shadow and cover against bird predators.

Another interesting design aspect could be that such a floating tube digestor could be manually rotated along its axis to provide for a better mixing of the slurry and thus increased bio-gas production.
Edit: Ah, and the mean temperature of the digestor should be more stable (but a bit lower due to evaporation) also, thus likely resulting in a more consistent digestion especially where there are bigger day/night temperature differences.

Anyways, please keep us updated on the results of this!

Re: Energy recovery & waste treatment with floating biodigesters (Tonle Sap Lake, Cambodia - LLEE) - by: robhughes

Thu, 23 May 2013 11:10:02 +0000

I've attached a recent Masters Thesis on the Environmental Sustainability of Floating Biodigesters on the Tonle Sap.

Re: Toilet System for Waste Separation and Dewaterization (TU Delft, The Netherlands) - by: KimAndersson

Wed, 22 May 2013 13:14:27 +0000

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

Increase of Biogas Production Using Low Cost Nanoparticles (Universitat Autònoma de Barcelona) - by: tonacho

Wed, 22 May 2013 07:51:58 +0000

See the effect of nanoparticles on the production of biogas from the anaerobic digestion of wastewater sludge after the lag phase.

(I attach Figure NPs1.JPG)

However, by the moment, we cannot reproduce these results to a pilot reactor (see Figure Reactor.JPG).

Some ideas?

A possibility could be that S can complex iron and deactivate the effect of nanoparticles, then, why this does not happen in batch mode?

Re: Developing fortified excreta pellets for use in agriculture project (IWMI, Ghana) - by: Ekane

Tue, 21 May 2013 19:22:00 +0000

Dear Funke and Josiane,

Ruth Cottingham has sent comments and questions regarding your project. She wrote:

“The Pollution Research Group at the University of KwaZulu-Natal is currently working on another Gates-funded project to carry out an economic evaluation of another pelletising process (LaDePa) for faecal sludge. A spreadsheet-based model is being developed to compare the whole life cycle cost of pelletisation with incineration as a disposal/reuse route.
Your work sounds very related to this and I would be really interested to know more. Are you able to share any reports resulting from it with us? We are particularly interested in understanding the relevant business models and economic inputs that apply to contexts outside of South Africa, in order to build the model with a structure that can be applied in multiple contexts.”

It is great that your projects are similar. Sharing findings and experiences from both projects would indeed be very useful.

Best regards,

Nelson

Re: Toilet System for Waste Separation and Dewaterization (TU Delft, The Netherlands) - by: jansengerwin

Tue, 21 May 2013 14:10:03 +0000

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

Re: Toilet System for Waste Separation and Dewaterization (TU Delft, The Netherlands) - by: KimAndersson

Sat, 18 May 2013 11:49:51 +0000

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.

Developing fortified excreta pellets for use in agriculture project (IWMI, Ghana) - by: Ekane

Tue, 14 May 2013 14:07:06 +0000

Olufunke Cofie and Josiane Nikiema of International Water Management Institute (IWMI) are developing pellets from human excreta for use in agriculture. Outlined below are details of their project.

Short description of the project:
Excreta are rich source of essential plant nutrients and organic matter that can be recycled as fertilizer-cum-soil conditioner – an effect not shared by chemical fertilizers and of dare need in tropical soils. While the principles that underlie the use of excreta in agriculture and associated benefits are known, the wide use of excreta is still constrained by factors such as the cost of transportation and handling as well as negative perception of communities with regards to using FS in agriculture. To address both challenges, this project hypothesized that producing excreta pellets could be the solution. The project explored ways to produce safe, efficient and cost effective fertilizer pellets from FS. The project focused on developing a marketable product from this waste, and explored options for pelletization of fecal sludge composts to increase; marketability, general acceptability, ease of handling and on-farm distribution, and to improve fertilizer use efficiency and affordability. The project involved a multi-disciplinary team of economists, environmental scientists, agronomists and engineers. The collective name for our various excreta based fertilizer formulations is referred to as Fortifer.

Objective: The main goal of the project is to convert excreta into safe and efficient fertilizer pellets that could enhance agricultural productivity in sub-Saharan Africa and make fecal sludge reuse attractive and profitable for private entrepreneurs.

Implementation process (attached)

Results:
The fecal sludge was initially dried, to remove excess water and sanitized through gamma irradiation (I-DFS), composting (C-DFS) and co-composting with sawdust (C-SDFS). For C-DFS, enrichment was performed through addition of nitrogenous fertilizer, to raise the level of nitrogen to 3% (EC-DFS). Each of these materials was then individually used for the production of cylindrical pellets. A binding material consisting of clay or cassava starch, pregelatinized or irradiated, at concentrations between 0 and 10 % in weight was added prior to pelletization. Equipment used in pelletization process was constructed in Ghana.

This study revealed that optimal moisture level, needed in the pelletizer’s feed, is highly dependent on material type with the lowest water amounts required for EC-DFS and I-DFS and the highest ones for C-SDFS. It is also affected by binder type and concentration, clay and lower concentrations requiring more water than irradiated starch and higher concentrations, respectively. The pellet’s length distribution was strongly affected by the starch pretreatment method as well as the type of pelletized material. Stability of pellets was affected by type of pelletized material, binding material’s concentration and moisture content. Producing dried pellets ensure reduction in the volume of fertilizer required in the field (50-80 % of the initial volume).

Video of her presentation at the FSM2-Conference in Durban, South Africa:

Conference presentation slides:
www.susana.org/images/documents/07-cap-d...kiema-iwmi-ghana.pdf

Conference paper:
www.susana.org/docs_ccbk/susana_download/2-1624-nikiema.pdf

Developing country where the research has been tested: Ghana
Start and end date: May 2011 to April 2013
Grant type: GCE Round 6
Funding for this research currently ongoing: No

Research or implementation partners:
• Tema Metropolitan Assembly, Ghana
• Centre for Scientific and Industrial Research (CSIR), Accra, Ghana
• Biotechnology and Nuclear Agriculture Research Institute (BNARI), Accra, Ghana
• Valley View University, Accra, Ghana
• University of Ibadan, Nigeria

Best regards,

Nelson

Re: Urine-tricity - Electricity from urine (University of the West of England, UK) - by: iaieropoulos

Thu, 09 May 2013 20:47:30 +0000

Hi there,

Thank you for letting us know about this.

It is of course brilliant that this project has been launched, however it's not directly related to electricity generation from urine, which is what the Urine-tricity project is about. From the information available on that website, the project you are referring to, is an innovative approach to recovering nutrients from urine, but not electricity.

Kind regards,
Yannis

Re: Urine-tricity - Electricity from urine (University of the West of England, UK) - by: MRonteltap

Thu, 09 May 2013 18:58:32 +0000

Hi all,

Just for your information:

A new EU project was recently launched on this with a pilot plant located at one of the Dutch water boards.

There is not much information yet on the website but I could imagine more will follow soon; you can follow here: www.valuefromurine.eu/.

(The fresh Dr.) Philipp Kuntke is managing the research; he can be reached under This e-mail address is being protected from spambots. You need JavaScript enabled to view it . I'll encourage him to also write a post here.

Mariska.

Re: Urine-tricity - Electricity from urine (University of the West of England, UK) - by: iaieropoulos

Thu, 09 May 2013 15:56:07 +0000

Dear Elizabeth,

Thank you for your message and the pertinent questions asked.

The amount of electricity produced from Microbial Fuel Cells (MFCs) is often a point of misconception, since different workers tend to quote different electrical output levels in the literature, using various normalisation methods. This is why in our work we have always been demonstrably proving the actual amount of electricity, by powering real world devices, such as: digital wristwatches, clocks, dc motors, dc pumps, LEDs, dc fans, whole robots such as EcoBots I,II and III (already published or publicised) and more... (not yet published). As Physicists, the only way to prove that something works is by getting it to do real work, and this is exactly what we have been showing over the years. The amazing thing about urine is that it increases the power output from our MFCs by at least 3x!
In terms of actual power output, our MFCs produce something between 100-300uW at approximately 0.4-0.6V, which is why we have been pursuing the miniaturisation & multiplication approach, when it comes to scale-up of size and electrical output.

The cost of these devices greatly depends on core materials & parts that are used in the assembly. Again, this is one area that we have considered seriously, especially in the context of communities with no access to high-tech facilities in the Developing World, which is of course one of the main criteria of the Bill & Melinda Gates Foundation. We have therefore calculated the cost of one of our 60mL MFC units, to be approximately £1.09, and this is what we would consider expensive, since it is the cost of the actual prototype. If mass-manufactured, then the actual cost/unit would be considerably less, which is what we are actively pursuing.

The answer to your question about the treatment of urine (i.e. after electricity extraction), is indeed in the presentation given at FSM2 in Durban, as well as in the RSC Physical Chemistry Chemical Physics, Journal (14:94-98) (pubs.rsc.org/en/Content/ArticleLanding/2012/CP/c1cp23213d).
But that's not the end! The MFC can produce cleaner (and I do choose my words carefully) water on the cathode side, as a result of its operation. Electrons and cations (including protons) coming from the bacterial half-cell, react with oxygen on the cathode half-cell, the by-product of which is water. Unless this reaction is completed, the MFC does not work, as shown in the plethora of oxygen-cathode-based MFCs in the literature. But one can collect water from the cathode, if one is careful about how this can be done. This is part of our work and the water collected (as shown in the FSM2 presentation) will need to be thoroughly analysed (not just using EDX as we have done so far), before we can make any further claims. The fact of the matter is that this water is cleaner than the wastewater or urine fed into the anode half-cell, and further uses (e.g. irrigation) of this cleaner water will become more obvious as we further analyse the samples.

Regarding the news story from the Lagos Maker Faire, I think it's remarkable that 14-15 year old girls from Nigeria have come together to produce that demonstrator, but there is a few elements to pay attention to. For example, the electrolytic cell by default requires electricity to operate, which as shown from the photos, comes from the generator. So one question one might ask would be, are the 6 hours of operation purely from the 1 litre of urine, or has the generator had some external energy input to begin with? Another thing to consider would be the elements and materials actually involved in the electrolytic cell, water filter and cylinder with liquid borax, what is their cost and what is their useful lifetime? In other words, how much would this system cost and how long would it last running? Although the setup might have been 'prep-ed' for the photo opportunity, there is of course the question of the loose tubes going into the compressed gas cylinder. And finally, 6 hours of electricity can mean a number things, and without proper quantification of this output, it is difficult to be conclusive.

Kind regards,
Yannis