Integrating microbial fuel cells into a urine diversion toilet
The Bristol BioEnergy Centre (BBiC) at UWE has been developing a microbial fuel cell (MFC) technology to produce electricity from urine and wastewater, in a single step conversion, by reducing Biological Oxygen Demand (BOD) or Chemical Oxygen Demand (COD) as well as pathogens. The MFC is an energy transducer converting the biochemical energy in organic waste (wastewater, blackwater, urine) directly into electricity, through the metabolic activity of constituent microorganisms. A single MFC generates approximately 1mW of power at al, on the UWE Campus for more than a year; which has served as a proof-of concept. Scaled-up Pee Power urinals were then successfully installed and operated during the Glastonbury Music Festival of 2015 and 2016 with 1000’s of people using them per day.
These small scale trials are very encouraging but fall short of demonstrating at scale the real world practical use of “Pee power” and MFCs. This proposal requests funding to continue the collaboration between UWE-BBiC and Oxfam to further refine the MFC technology and production cost and then demonstrate its potential by extending and expanding the field trials to developing world contexts of an urban slum and refugee camp. The project seeks to demonstrate the practical use of the technology by addressing major problems being faced by the poorest and most marginalized people in the world related to sanitation, safety and protection. Integrating MFCs into a urine diversion toilet not only utilizes a waste product that has no productive purpose, the by-product is also less harmful and has less odor that the original urine.
The previous work demonstrated the robustness and capability to work within a wide range of parameters, but it also revealed some of the limitations in terms of organic waste treatment under suboptimal hydraulic retention times (excessively high/low throughput). These have already served to educate the BBiC team on how to optimize the MFC modular design, which has been implemented for Glastonbury 2016. This new design is subject to further optimization as part of a calibration trial (about to begin with a commercial partner) but it currently shows the highest power output (~50mW/module) and is therefore the closest design in mind for powering outdoor lighting of 6-meter radius.
The initial primary focus of the current grant will be on powering outdoor (preferably) LED lighting with the minimum number of MFC modules, and compaction of the MFC design to sit underneath each toilet block. It is planned to construct 5 toilet blocks (of 4 UDT cubicles each) at each location (a total of 10 toilet blocks) constructed from locally appropriate, durable materials . The final design and siting will be informed by discussions with users.
This is a partnership between the University of the West of England's Bristol Bioenergy Center and Oxfam GB.
Task 1. Establish MFC manufacturing route, receive first modules for testing and assess performance in the lab. This is not necessarily complicated, but may be expensive, due to tooling/moulding, as it will be the first time the contract manufacturer will be producing these from the MFC design given by Bristol BioEnergy Centre BBiC.
Task 2. Manufacturing of 1,500 MFC modules following the completion of Task 1 above. There will also need to be some lab testing to assure quality of modules.
Task 3. Identification of sites for on-site toilet construction. This task will be commissioned by Oxfam and will involve the local communities in the slum and the refugee or IDP camp, so that the toilets become a longer term utility for the people. It is anticipated that the slum context will be in Sierra Leone but identifying a camp location one year in advance is not possible as the camp may currently not yet exist. Current sites under consideration include Tanzania and Democratic Republic of Congo. Criteria used to determine sites will be i) clear identified need for sanitation and risk of gender based violence, ii) capacity and enthusiasm of the Oxfam Country team to participate and monitor the project, iii) conducive external environment including no significant import restriction/prohibitive tariffs on goods, iv) supportive host government/local leadership, v) stable security and vi) expectation that the camp is semi permanent in nature and will continue well beyond the project duration. The timing of construction will be phased according to delivery of the MFCs to ensure the toilets can come into full operation as soon as fuel cells arrive in country. BBiC will visit each site to confirm MFC and lighting-related requirements.
Task 4. Installation of MFCs at each toilet block and wiring for outside lighting. This will be subject to shipping times/delays and customs clearance, and will involve the physical assembly of MFC modules into stacks/cascades, with sufficient time for inoculation and maturing to maximum power output (2 weeks). During the installation and maturing, training will also be provided to Oxfam personnel as well as to people from the local communities.
Task 5. Testing and validation of toilets on site. This will primarily be carried out by Oxfam personnel along with representatives from the local communities, subject to training from BBiC staff.
In addition to the groundbreaking operational research on MFC technology and the long term contribution this could make towards addressing the planet’s future energy needs, this project will have an immediate and long term benefit for between 500 and 1,000 people who would not have access to safe sanitation without this project.
Bill & Melinda Gates Foundation Camps (emergency or longer term) Emergency and reconstruction Energy: electricity, hydrogen, fuel cells Europe, Caucasus & Central Asia Fundamental research and engineering Global International NGO Product design and engineering Renewable energies and climate change Resource recovery Urine
Esther Shaylor (eshaylor)
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