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Where people can't flush, our team is developing a portable toilet that evaporates 90-95% of onsite sewage converting it into clean water


Description

Summary

We propose to demonstrate improved quality and accessibility of urban sanitation in the Kiboga District of Uganda using our iThrone toilets. Like 2.6Bn people globally, the people in this community largely lack access to safe, dignified toilets, due to insufficient plumbing infrastructure. Poor sanitation perpetuates poverty, poor health & pollution (not only water pollution but also significant methane emissions from raw sewage waste that remains uncollected and untreated in poor communities). Clearly, facing a global population of 10Bn, where most people live in crowded cities with insufficient or ageing infrastructure, and if we want everyone to have access to safe, clean, sustainable sanitation, we need a new way to “flush”—a low- cost solution that doesn’t use or pollute water or emit or contribute to carbon. If we want everyone everywhere to have access to safe, clean, sustainable sanitation, we need to find a new way to “flush”—a low- cost solution that doesn’t use or pollute water or emit or contribute to carbon. Our team has a goal to promote increased availability and adoption of improved sanitation in un-sewered areas (especially in urban areas and congested informal settlements). In order to increase access to and use of safe, hygienic toilets, we have developed the “iThrone”, a portable, sewage-evaporating toilet that aggressively evaporates (or “flushes” away) >95% of daily sewage onsite! The iThrone installs anywhere: it's compact enough to fit anywhere and can achieve rapid sewage reduction onsite without hookups to power or plumbing infrastructure. It also drastically reduces the frequencies, volumes and thus costs for sewage collection. As such, we believe the iThrone is only solution that can fill the need for clean, convenient sanitation in rapid-growth urban areas that lack sewerage, and also that can support scalable, sustainable servicing models for sewage removal.


Is this proposal for a practice or a project?

Not sure


What actions do you propose?

Our project aims to demonstrate the impacts of improved quality of and access to clean, sustainable sanitation in an urban setting, specifically in the Kiboga district of Uganda, partnering with the District government and local health and sanitation NGOs.

 

change:WATER Labs will deploy 5-10 iThrone toilets to Kiboga, to be hosted by the District Hospital and School, both of which currently rely on poorly maintained pit-latrines (our toilets will be installed next to the current onsite sanitation options). The lack of clean and conveniently accessible toilets causes difficulties for students and faculty at the school, and for patients and their families who stay at the hospital. Lack of toilets at the school makes it difficult for students and teachers (especially the females) to get through each day of schooling. At the hospital, the pit latrines are actually quite difficult to access and are very unhygienic. Patients and their families often have to live at the hospital during treatment (as they travel from various distances), and have no better sanitation alternatives. The staff at the hospital prefer, instead of using these pit latrines onsite, to go home during their work shifts to use their home toilets. Pit latrines can spread disease due to poor hygiene conditions and leaching of sewage waste into the surrounding environment—also people might instead prefer open defecation or “flying toilets” as an alternative.

 

change:WATER Labs will deploy and monitor the use and impact of these iThrone units at the hospital and the school. Our team will track usage and performance of the toilets, and will also gather feedback from users, servicing partners, host institutions and other local stakeholders about the performance and design of our toilets. We will also work with local government and the Ministry of Agriculture to explore the potential to use the dehydrated waste for some productive purpose in agriculture (in line with current local practices). We will additionally work with another Ugandan sanitation company that is interested in our toilets for their operations—this company is interested in using our toilets to reduce their service operations costs.

 

The demonstration toilets will be hosted by 3 local partners: the school, the District hospital and the local sanitation company (which provides pay-per-use toilets to the community at large). These demonstration units will be monitored for the following metrics:

  • usage (number/frequency of users per day)
  • comparative usage of our toilets versus current onsite options (eg pit latrines)
  • volume of waste collected per day (implies volume of waste averted from the environment)
  • volume of waste evaporated per day
  • performance and robustness
  • number of days/weeks of usage between needed servicing trips (and the related servicing costs), and how this compares to other container-based toilet options
  • qualitative user feedback and user experience
  • qualitative data on cleanliness
  • qualitative feedback from servicing partner on servicing of our toilets versus pit latrines and container toilets (also to use this feedback to improve toilet design and servicing protocol)
  • comparative upfront and ongoing costs of our toilets per user versus comparable alternatives

 

In addition, the project will explore post-servicing option for waste disposal and conversion. The local government and partners have an interest to explore potential to monetize the collected dehydrated waste (potentially for agriculture or energy). They also are proposing potential to harvest the pure water vapor rendered by our toilets for productive use—this water would be 100% pure (given that our technology essentially mimics distillation but without need for external heat sources).

 

iThrone Technology details:

To drive the rapid dehydration of urine and wet feces, we have developed a proprietary evaporative or breathable membrane material that acts similarly to sweat-absorbing clothing or breathable building materials—soaking up liquid moisture and then “sweating” it out as molecular/gaseous (pure) water. This phenomenon—also called “moisture diffusion”--is largely driven by the difference in humidity between the wet side of the membrane to the dry side. We describe how the iThrone processes waste below (see graphics: http://bit.ly/cWLcolabpix; and demo video: http://bit.ly/cwlcolab):

  • Liquid/Solid separation: At first, liquid and solid waste are separated in our system (depending on whether the system is “sit” or “squat”, we have different approaches to separating these streams into different evaporative pouches so they don’t mix).
  • Evaporation/Waste-dehydration: The pouch material swells on contact with wet waste, soaking up the water. This absorbed water then “sweats out” of the pouches, released as gaseous (pure molecular) water to the air. Urine is almost 100% water by volume, and thus is essentially completely evaporated by our evaporative pouch (with only residual salts left behind in the pouch). Wet feces are ~75% water. Our evaporative pouch will dehydrate much of that volume, again releasing only pure (molecular) water vapor to the atmosphere, while hygienically (safely) containing residual dried solid waste inside the evaporative pouch. Dehydrating waste not only shrinks daily collected volumes onsite, but also stabilizes the residual waste, shutting down (even killing) much of the microbial activity.
  • Odor management: In addition to shutting down microbial gas production, our “pee-powered” microbial fuel cell powers an internal ventilation system that helps to accelerate waste evaporation and dispel odors.
  • Servicing/Sewage-removal: Because we are targeting crowded (ie space-constrained) non-sewered communities, onsite waste accumulation is rapid and relentless, requiring aggressive sewage removal services. No/low-service solutions either are dangerously slow at neutralizing onsite waste (composting) or require huge footprint or digging of large pits (latrines). These solutions leave communities dangerously exposed to large volumes of onsite waste accumulations. So, currently, active waste removal is really the only safe option in high-density areas where waste can’t be flushed away. So decentralized sanitation must be managed similarly to garbage collection, utilizing container-based sanitation (CBS) solutions--which require active waste collection by so-called “fecal-sludge management”/FSM servicers. Our iThrone system also requires waste-removal servicing, but MUCH less frequently. While all other container-based solutions require frequent waste removal (generally every 1-2 days due to rapid onsite accumulation), our waste-evaporating solution drastically reduces that frequency by 15-30x (ie 1-2x/month). As such, our solution is an enabling tool that allows servicers to reduce collection costs and scale their operations. We’ve heard from servicers that even if our solution only reduces collections to 1x/week, it could reduce their OPEX costs by 30-50%. The reduced collection frequency per toilet would translate to servicers being able to scale their operations—servicing up to 20x more toilets with their existing-sized fleets. So, the iThrone allows FSM servicers to be MUCH more scalable and profitable. Servicing of the iThrone involves swapping used pouches for fresh ones. In future, we look to evolve our material to be more re-usable or biodegradable, but at present, we expect to be able to re-use or re-purpose 70-90% of the material. Also, biodegradable bags for fecal collections are only effective if they are collected in a timely manner, so biodegradability is not necessarily a panacea in this case. Also, our use of plastic is 20-40x less than plastic used per user in the currently common practice of “flying toilets”.
  • Post-collection processing: Waste-processing isn’t one-size-fits-all—it varies according to the needs and capacity of different servicers or communities. We cannot be proscriptive about what will happen to the waste, as that determination will depend on the communities we work with--Whether the approach is disposal or waste-to-value conversion. But our system will generally integrate into either post-collection processing regime fairly easily.
  • Future enhancements: Our focus currently it to get our first version of the iThrone out as quickly as possible to address the crisis of poor or non-existent sanitation in many urban, displaced and vulnerable communities. In parallel, we are also developing enhancements that can upgrade our deployed toilets to improve sustainability of the pouches, further disinfection of the collected waste, and potential increase in the power generated by the bio-battery to provide power to other applications (eg cell phone charging, lighting, etc).

 

Working with communities: Regarding community deployments, we cannot presume to have expert knowledge of each local context and so, as mentioned above, we will work closely with local partners in target communities to (a) adapt our toilet to local preferences and needs and (b) integrate into local WASH operations (especially around servicing and post-collection processing). Through these partnerships, we hope to enter into communities via trusted channels, and we also view these partnerships as vital to achieving successful deployment and positive impact. For example, in our first deployment in Uganda, we already are partnering with the local district government, community WASH advocates, health providers and the District Hospital, women’s groups, the District’s Department of Education and two local sanitation-service/FSM partners to adapt the installations of our toilets to local needs, preferences, requirements and capacity. Initial deployments will be located at the district hospital and the school, and we will be developing servicing and processing regimes in partnership with the FSMs and the District’s Department of Agriculture (which has an interest in utilizing the collected waste outputs for potential agricultural applications). (see below for further details.)


Who will take these actions?

change:WATER Labs (cWL) will provide the 5-10 iThrone units, replacement components, usage, servicing and results tracking protocols. Also, our team will install the toilets, build the shelters that house the toilets, wire up the remote sensors (which will track toilet performance and alert us if toilets malfunction), and the waste storage/treatment capacity. Alongside local community partners, our team will also run capacity-building workshop with the local servicing partners and local institutional hosts—we will develop the training materials, field testing protocols and usage/servicing manuals. We will also run post-project feedback sessions with users, servicing partners and other local stakeholders.

 

NGO partner, Israeli Medicine on the Equator, which operates the Kiboga District Hospital, is our key on-the-ground partner. They will host most of our deployed toilets on their campus, and will hire someone to manage the day-to-day cleaning and monitoring of the pilot. They have also facilitated a number of local introductions to potential partners for this proposed project, including the district government administrators.

 

Another local NGO called Door-to-Door will help facilitate workshops to educate users on the benefits of improved sanitation practices and use of our toilets. They will also help us to develop servicing protocols.

 

A local sanitation business, Joelex, is very interested in our toilet hardware as potentially reducing the costs of installing and operating their pay-per-use toilet installations. They would potentially host some of our toilets to monitor performance and servicing costs.

 

Kiboga’s Chief Administrative Officer (CAO) has expressed interest in this project, and has also facilitated introductions to the local Ministry of Agriculture, which has an interest in exploring potential options for waste-to-fertilizer applications of the waste collected in our toilets.

 

IME’s and D2D’s guidance and input are critical to the success of this venture. The hardware developed by cWL will only succeed if the solution aligns with the needs of local institutions like IME & the servicing/waste-disposal capacity of D2D and other local fecal-sludge management (FSM) providers. cWL relies on IME & D2D to provide key usage/design specifications, installation locations, user/servicer training and monthly maintenance/waste-removal. cWL is, in essence, developing an enabling tool to allow local sanitation providers to scale access to safe, dignified sanitation at much lower cost. But sanitation/waste-collection absolutely relies on the local implementation partners. Our servicing partners will also need training on how to service our toilets safely to protect end-users & their collectors. We also would like to work with servicers to develop improved sustainability practices around waste disposal (eg waste-to-value conversion).


Where will these actions be taken?

Initially, for this proposal, the project will take place in Kiboga District in Uganda. However, the data from this project will inform development of our sanitation solution for much broader application and deployment in many urban settings around the globe. The challenges for sanitation in Kiboga are common to many low-resource urban settings, as well as informal settlements where 1Bn people live (slums, refugee camps, displacement camps, post-crisis situations, etc). Our toilet is designed to be an adaptable solution that can be easily customized to fit the local preferences around sanitation, while also solving the universal issues of aggressive onsite waste accumulation (ie the need for hygienic containment, volume reduction, reduced collection frequencies and costs, improved user experience). Because our toilet assumes no support from external infrastructure, it is a drop-in solution that can provide convenient, clean, safe, low-cost sanitation anywhere. Because our toilet not only does not use or pollute local water, but in fact turns 95% of daily onsite waste INTO clean water, as well as quickly dehydrating waste to cut of methane emissions from raw sewage, our solution is uniquely positioned to mitigate and adapt to climate change and provide clean, sustainable sanitation.

 

In a little over a decade, 5Bn people effectively won’t be able to flush, dependent on decentralized sanitation systems. We urgently need a massively scalable, sustainable way to manage our sewage safely. With our waste-evaporating solution, change:WATER Labs has the potential to transform how we handle human waste. Our approach re-invents the future possibilities for sanitation, where, instead of consuming water and polluting the environment, our toilet recovers clean water and generates energy, cleaning up communities and curbing carbon emissions. By In solving sanitation access, our team has the opportunity to promote cross-cutting social and global environmental impact with just one intervention: improving health, gender empowerment and economic opportunity while improving water security and curbing climate change. Our toilet re-imagines sanitation for a healthier planet.


In addition, specify the country or countries where these actions will be taken.

Uganda


Country 2

No country selected


Country 3

No country selected


Country 4

No country selected


Country 5

No country selected


Impact/Benefits


What impact will these actions have on greenhouse gas emissions and/or adapting to climate change?

Poor sanitation poisons the environment and contributes to climate change. Every day, in un-sewered communities, 80% (4Bn L/day) of raw human waste is uncollected, polluting poor communities and poisoning their water sources. Distributed wastewater is one of the biggest yet invisible contributors to carbon emissions. Decentralized human waste contributes 4% of man-made methane emissions (methane is 25x more potent than carbon dioxide as a greenhouse gas). But, the current alternatives—flushing or frequent sewage collection--are bad for the planet, consuming water and contributing to carbon emissions.

 

By rapidly dehydrating raw sewage waste onsite, the iThrone cuts off methane production from wet raw sewage. Just one of our iThrone toilets shuts down 10-100MT emissions/household/yr from methane off-gassing (equivalent to the carbon emitted driving 1500-3000 miles/yr, or one fifth the distance an average American drives per year).

 

Other measurable environmental benefits would include reductions in: onsite waste accumulation & discharge, haulage frequencies & fuel use. Our solution promotes sustainable sanitation, by averting pollution from the environment, conserving fresh water and avoiding carbon emissions from decentralized waste. Not only does the iThrone NOT need external energy, it converts waste INTO clean power. Rapid dehydration (ie shrinking) of daily onsite waste volumes reduces carbon emissions, avoiding 9-45MM gal gas/toilet/yr (due to reduced frequency of sewage collection and haulage).

 

Not only does the iThrone NOT use or pollute water, it converts waste INTO pure water (and thus avoids the energy used to convey flush water to/from toilets, but also the energy that would be needed to treat the effluent wastewater). One iThrone could replace a flush toilet, thereby avoiding flushing 20K-130K gal/yr of clean water (flushing uses ~12-130x more fresh water than flushed waste per household daily).


What are other key benefits?

Poor sanitation traps communities in perpetual poverty, poor health and pollution. It causes 80% of all infectious disease, 4% of all deaths and takes the life of one child every 20 seconds. Poor sanitation costs 5.5Bn days/yr in lost productivity and $260Bn/yr in economic losses (as much as 5-6% of GDP for affected countries).

 

The lack of safe, private, accessible sanitation has especially dire consequences for girls and women globally. Females who lack access to private toilets in their homes, and are forced to relieve themselves in public, face daily peril in this routine act--risking rape, attack, even death. Also, the lack of toilets in 55% of schools around the world presents daily challenges for girls to attend school and participate in their educations, leading to >20% dropping-out by puberty— rendering them susceptible to early marriage and childbearing, and all but ensuring them a future life of poverty.

 

Improving sanitation quality and access benefits affected families, their communities and, in fact, all of us. Installing an iThrone in the home of a family who lacks access to safe, conveniently-accessible toilets would have a multiplier effect, reducing their daughter’s susceptibility to sanitation-related sexual assault, their children’s risk of diarrhea and their community’s exposure to vector-borne infectious disease.

 

Our aim is to provide safe, clean, dignified toilets to 2.6Bn people living without proper, accessible sanitation, for whom there are currently NO GOOD solutions. By drastically reducing the costs of decentralized sanitation, our solution benefits each actor along the sanitation value-chain:

--For users, the iThrone makes it possible to have a clean, safe, dignified and conveniently-accessible toilet in every home;

--For servicers, it enables their waste collection operations to be much more profitable and scalable; and

--For governments and NGOs, the iThrone cuts costs to provide more people with decentralized sanitation.

 

Our toilet keeps things clean, reduces odor and can install anywhere--ideal for domestic sanitation in crowded urban slums and refugee camps. And it’s the only toilet that can drop into an emergency to provide immediately safe sanitation.

 

The iThrone will get safe sanitation to more people—in slums, refugee camps and crisis situations. By shrinking sewage, the iThrone cuts costs while increasing toilet access and servicing efficiency. The cost to install and maintain one communal toilet could instead fund FOUR of our household toilets. For waste collectors, instead of repeatedly servicing a small number of container toilets daily, they could service up to 20x more of our iThrones monthly.


Costs/Challenges


What are the proposal’s projected costs?

The project will support deployment and testing of 5-10 iThrone toilets to Kiboga district in Uganda. The high-level budgeting for this project includes: $4K for materials to construct/deploy iThrones; $3K field help and engineering; $3K for travel and logistics; $1K for capacity building and data gathering. This project will make partial use of engineering capacity, facilities and materials that have already been funded by other sources.

 

iThrone economics: At scale, we project our toilets will cost ~$200-300 each, depending on the sizing (ie capacity for the expected number of users—between 6-50 users/toilet/day). This is compared to similarly featured/comparable toilets (which cost $600-1000 each, and often require external support components, eg water tanks, collection tanks, etc, which can add hundreds to thousands more to the installation costs). Also, comparable toilets either require ~$40/mo/family in costs and/or daily collections/servicing. Depending on the size of the iThrone and servicing frequency, we project servicing costs of $5-10/mo/toilet (toilets servicing 6-50 users/day). So in terms of upfront and ongoing servicing costs, our iThrone costs at least ¼what the comparable options cost.

 

The key dependence of our toilet, as well as any other container-based toilet option is the requirement for periodic waste collection. Any toilet that captures and contains waste onsite (rather than discharging it) requires that collected waste to be collected and removed (similar to garbage). However, our toilet greatly reduces that collection frequency by 15-30x (instead of almost daily collection, our toilet only requires collection 1-2x/month). The collection pouch facilitates this rapid onsite evaporation is a consumable that has to be replaced with each servicing cycle, but it will be very low-cost (cost and replacement frequency will depend on number of daily users).

 

The greatly reduced collection frequency enabled by our toilet could reduce servicer collection costs by 50%, and also allows servicers to service up to 20x more toilets with their existing fleets. On a per user basis, our household toilet and the servicing of it will cost one-fourth the installation and maintenancing costs of a communal toilet.

 

While composting toilets also reduce the need for waste collection, they do not work well in crowded, domestic and/or low-resource settings, because they often discharge the liquid waste onsite to reduce volume of the waste contained in the toilet and also, they often fail due to improper maintenance—and as such can be vectors for disease spread.

 

The replaceable evaporative pouch is indeed a consumable, however, 70-90% of the material can be reused. And ultimately, use of our pouch (each of which is only a few grams and is only replaced every 2-4wks) results in 20-40x less plastic use than what users use for the prevalent practice of “flying toilets”.


Timeline

Our project would have immediate impact in terms of providing safer and cleaner sanitation option to the patients at the Kiboga hospital, their families and the students at the school. Currently, these users only have the option to use unsanitary pit latrines which, in these locations, are not even very accessible. Our toilets would be a more accessible, safer, cleaner option—in containing and quickly reducing onsite waste volumes, and reducing sewage waste discharge in these locations. At the school, students, especially girls, will have an easier time to attend and participate in class on a daily basis. Having a safer, cleaner, more accessible option should also reduce the frequency of people practicing open defecation and other similarly unsanitary options. The host institutions should also see a fairly immediate reduction in maintenance and servicing costs versus their other container-based toilet options.

 

In the 1-15yr term, our toilets have the potential to greatly increase availability and accessibility of safe, clean sanitation—because they are low-cost (to purchase and maintain) and can be installed anywhere (due to their compact footprint and stand-alone operability). Compared to communal toilets, our toilets cost one-fourth to install and maintain—thus supporting a 4x increase in accessibility. Our toilets would also enable significantly increased scalability and profitability of sewage collection (FSM) operations, which in turn will allow decentralized sanitation services to grow and be more affordable, accessible and efficient. Our toilet, by drastically reducing waste collection frequencies (15-30x) in turn reduced OPEX costs (potentially 50% or more) and increases servicing coverage (ie the number of toilets serviceable per collector) by up to 20x. Only by cutting costs and increasing servicing capacity can we hope to achieve safe sanitation access for everyone.

 

With increased availability of our iThrone toilets, we expect increased practice of improved sanitation, which cleans up communities and their water resources. This in turn will reduce exposure to sanitation-related disease (especially vector-borne disease). Just one toilet could reduce vector-borne disease exposure to everyone living in a 0.25-0.5km radius (>500 people in a densely-populated urban area).

 

In the medium term, we expect our toilets will have deliver economic benefits to communities: increased access to safe sanitation (which translates into improved health and productivity for users and their communities); and increased profitability and scalability for FSM businesses and waste collection service providers.

 

In the long term, we hope our toilet to translate into macro-scale environmental benefits: reducing methane emissions from decentralized waste; and reducing strains on fresh water resources (reduced use and pollution). Our technology is the only emerging solution that can hope to support safe, clean and sustainable sanitation for everyone.


About the author(s)

change:WATER Labs Inc. was founded in 2015 by 2 female entrepreneurs, Dr Diana Yousef, PhD, MBA (CEO) and Huda Elasaad, MS (CTO), who bring together 20+ years of experience from serial cleantech/hardware startups, as well as water systems engineering, venture investing and business strategy.

 

Diana Yousef, PhD, MBA, MA:

Co-founder: Life Sciences Investment Group, International Finance Corporation/World Bank; Growing Sustainable Businesses Initiative (pro-poor business accelerator), UNDP; several cleantech and social ventures (solar, watertech, waste recycling).

Previous work experience: seed-stage venture investor in cleantech, biotech and IT startups.

Education: Biochemist (B.A., Harvard; Ph.D., Cornell), MBA and MA in International Development (Columbia).

Other recognition: inaugural member of TED Fellows Advisory and Selection Committee; Founding Council Member for NASA/USAID’s LAUNCH Accelerator; 2017-8 Inventor Ambassador (American Association for the Advancement of Sciences and the Lemelson Foundation); 2018 finalist for the Cartier Women’s Initiative Award; Top 5 Winner, 2018 Chivas-Regal Venture Competition; 2018-9 Top 10 Finalist for the African Innovation Prize.

 

Huda Elasaad, MS, MS:

Co-Founder: PVPure (PV-powered community-scale water treatment plants, using innovative smart-controls algorithms to lower costs and improve output efficiencies).

Previous work experience: extensive applied experience in water treatment and innovation, including municipal plant operations for wastewater treatment, desalination, and water process engineering.

Education: Geohydrology & Aquatic Chemistry (BA, McGill; MS, UMichigan).

Other recognition: published author in the fields of environmental public health, water treatment design, maintenance optimization and field applications; co-authored patents on industrial and environmental chemical contamination and control. 2017-8 Inventor Ambassador (American Association for the Advancement of Sciences and the Lemelson Foundation).


Related Proposals

Here below are some other potentially related CoLab projects that focus on mobile toilets and in-home sanitation:

https://www.climatecolab.org/contests/2019/reshapingdevelopmentpathwaysinLDCs/c/proposal/1334641

https://www.climatecolab.org/contests/2015/harnessing-the-power-of-mit-alumni/c/proposal/1325341

https://www.climatecolab.org/contests/2018/helping-small-medium-businesses-go-low-carbon-ontario/c/proposal/1334533

https://www.climatecolab.org/contests/2017/absorbing-climate-impacts/c/proposal/1334401


References

http://hystra.com/sanitation

https://pubs.acs.org/doi/10.1021/es501549h

https://www.hrw.org/report/2017/04/19/going-toilet-when-you-want/sanitation-human-right

https://www.un.org/en/events/toiletday/assets/img/posters/fact_sheet_toiletsandjobs_EN_3.pdf

 

https://thebossmagazine.com/magazine/april18/

https://www.fastcompany.com/40550779/this-toilet-vaporizes-poop-to-solve-sanitation-problems

https://www.youtube.com/watch?v=Rc95OKDjabU

https://www.thedailybeast.com/how-a-toilet-that-vaporizes-poop-might-transform-the-world

 

https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-016-3797-z