BY ERIC HE
Eric He is a second-year International Development student at SAIS.
A Dire Situation Calls for Non-traditional Approaches
Climate change and water scarcity are closely related. The increasing unpredictability of climate leads to the higher volatility of water supply, making its capture more challenging.[1][2] On the other hand, population growth pushes up the demand for clean water. [3][4]. According to the World Health Organization (WHO), 50% of people in the world will live in water-stressed areas by 2025.[5] To make things worse, more than 2 billion people are acquiring their drinking water from water sources contaminated by feces.[6] A family of four with a standard toilet connected to sewage uses about 11,000 – 26,000 gallons of water per year.[7] Many overcrowded and water-stressed informal settlements simply do not have enough water to flush toilets; therefore, on-site sanitation becomes a common option in these settlements. However, many pit-latrines are not appropriately emptied with human excreta often dumped directly into rivers, contaminating the already scarce water sources.[8] Facing the dire situation, informal settlements need non-traditional approaches that account for the challenge of water scarcity.
The Bill & Melinda Gates Foundation (BMGF) “Reinvent the Toilet Challenge,” initiated in 2011, offers grants to encourage the invention of “unconventional ‘high-tech’ solutions”.[9] The Blue Diversion Toilet (BDT) and Blue Diversion Autarky (BDA) toilet were such inventions. BDT and BDA are indeed innovative because they incorporate an on-site water recycling system and an on-site treatment system (BDA only), but their complicated designs plus high costsmake them difficult to expand. When technological solutions are sought without corresponding investment in strengthening institutions the pursuit of high-tech innovations becomes an end itself instead of a means to address the real issue.
BDT and BDA: Dry Toilets with Water
BDT and BDA are two toilet designs in the Blue Diversion project. BDT is an “attractive source-separating toilet” with urine and excreta being diverted to separate containers beneath the pan.[10] A water tank, which is also the water recycling system, stands behind the pan, and provides water for hand washing, anal cleansing, and the cleaning of the front pan. The water is collected separately and goes back to the tank after being filtered by the gravity-driven ultrafiltration (UF) system. The system is powered by a solar panel installed on the roof and the power is stored in a battery at the back of the toilet.[11] Twice a week, collectors will transport the urine and feces to the Resource Recovery Plant (RRP), to be transformed into agricultural products.
Blue Diversion Toilet
Source: Tobias, et al., 2017
BDA is a more recent model of the design and has inherited the idea of on-site water recycling but dropped the concept of an offsite RRP. Instead, BDA has incorporated an on-site treatment system which treats urine and feces separately, producing fertilizers on-site.
Pilot Tests of BDT
The BDT was pilot tested in Kampala and Nairobi. From April to July 2013, one toilet was installed at Makerere University, Kampala for pretest, then used in Kifumbira slum for 3 weeks, and finally used in Kisalosalo by selected households. The research team conducted interviews and surveys in the communities where the toilets were installed.[12] The toilet was used around 1500 times in 70 days and it went through only minor maintenance. The concept of on-site water recycling was welcomed but there was concern about the odor, the design of the feces compartment, and the size of the toilet.[13][14][15]
Based on the lessons learned, the team designed the second working model and carried out another pilot test in 2014 with Sanergy, a company promoting container-based sanitation across informal settlements in Nairobi. The BDT team interviewed 60 regular users and 300 one-time users and received a much more positive response. All interviewees liked the look of BDT and 95% thought it was easy to use. The toilet was functional throughout the test.[16]
The BDA has not been yet tested in the field.
When Innovations Become Weaknesses
The on-site water recycling and the on-site urine and feces treatment are outstanding innovations from a technical perspective as water is scarce in many informal settlements. However, BDT and BDA face an abysmal prospect of expansion as their designs complicate the management.
BDT is not large enough to be used by many people while it is not small enough to be installed inside the household in a typical slum. Each BDT is designed for the use of 2 households with a total of around 10 people,[17] which means if the households are not living inside a compound managed by a landlord, the toilet has to be installed outside in the public and managed by the two households collectively. Can they make sure that only members of the households have access to the toilet? This might be tricky in informal settlements where the flow of people is high and unpredictable. Now assume that the households successfully prevent the use by outsiders, what if one household leaves all the cleaning to the other and in the end, both households simply stop cleaning the toilet at all? In addition, since users pay a monthly rent to use the toilet, what will happen if one household stops paying the rent while the other one keeps paying? If the toilet is closed to one household but remains open to the other, can the toilet still be profitable? None of these questions have been explored by the BDT team due to the extremely limited scale and duration of the two pilot tests.
The relatively complicated designs of BDT and BDA challenge the maintenance staff. The more parts they have, the more maintenance is needed, no matter how “durable” they are in a lab setting. In the case of BDT, it is claimed that the water recycling system barely needs maintenance,[18] but what about the solar panel, the battery, the foot pump, the tap and the shower head? The BDA design is even more complicated.[19] Someone has to refill the chemicals, ensure that the ventilators are working, and check if all the pipes beneath the toilet are firmly connected. And all these are just the regular maintenance. Irregular maintenance is also needed to deal with theft and vandalism, which are not uncommon in informal settlements. Therefore, a guard must be present at all times, incurring more labor costs.
As far as costs are concerned, BDT is not financially sustainable. The estimated revenue of each toilet is 7 cents per person per day.[20] With 10 people using the toilet, the annual revenue is around $250 per toilet. While the team claim that this revenue makes “the business model robust” under the assumption of mass production and expansion, it is unlikely the annual revenue can even cover the cost of manufacturing and installation. The container-based sanitation provided by Sanergy in Kenya, which has a much simpler design, costs $350 to fabricate and install.[21] With a much less demanding maintenance responsibility, Sanergy still incurred a total cost of $1.5 million in 2017 and only recovered 19%.[22] In addition, since BDT adopts a renting system instead of charging an up-front installation fee, the cost recovery would be much slower. In terms of BDA, although it does not have a business model yet, the much higher fabrication and maintenance costs make its application in informal settlements even less promising. The complicated designs, ambiguous assignment of management responsibility, and unsustainable financing indicate that neither BDT nor BDA can be scaled up and enjoy economy of scale.
Lessons from the Blue Diversion Project
There are two lessons we can learn from the Blue Diversion project. First, there is a significant gap between the context of a lab and that of an informal settlement, and therefore rigorous testing is needed at a representative scale. This is especially true when the goal of the project is to provide a service that is intended to function for a long time and serve a lot of people. The pilot tests conducted by the BDT team was too short and the sample size too small. The overwhelmingly positive responses from test users are unreliable because they might simply rate anything better than the status quo positively. This case demonstrates the importance of getting social scientists who are experienced in field research involved in a team of engineers.
Second, an innovation does not have to be “high-tech.” Truly valuable innovation addresses an issue cost-efficiently. Observing the trajectory of the Blue Diversion project, it is amazing how scientifically innovative it is on the one hand, and how far it is moving away from the people that it initially intended to serve on the other. By adding more pipes, more containers, more solar panels, and anything else that is more “high-tech,” the Blue Diversion project will make more appearances at toilet expos than in informal settlements.
[1] Climate Central. “Warmer air means more evaporation and precipitation.” September 6, 2017. https://www.climatecentral.org/gallery/graphics/warmer-air-means-more-evaporation-and-precipitation
[2] Chris Sall. “Climate Trends and Impact in China.” Washington, DC: World Bank, 2013. https://openknowledge.worldbank.org/handle/10986/17558
[3] Jianhua Wang et al. “Beijing’s water resources: Challenges and solutions.” Journal of the American Water Resources Association, 51 (3) (2015): 614-623. DOI: 10.1111/1752-1688.12315
[4] Diana Mitlin et al. “Unaffordable and Undrinkable: Rethinking Urban Water Access in the Global South.” Working Paper. Washington, DC: World Resources Institute, 2019.
[5] World Health Organization. “Drinking-water.” June 14, 2019. https://www.who.int/news-room/fact-sheets/detail/drinking-water
[6] Ibid
[7] Home Water Works. “Toilets.” Accessed December 19, 2019. https://www.home-water-works.org/indoor-use/toilets
[8] World Bank. “Evaluating the Potential of Container-Based Sanitation: Sanergy in Nairobi, Kenya.” Washington, DC: World Bank, 2019. http://documents.worldbank.org/curated/en/661201550180019891/pdf/Evaluating-the-Potential-of-Container-Based-Sanitation-Sanergy-in-Nairobi-Kenya.pdf
[9] Tove A. Larson et al. “Blue Diversion: A New Approach to Sanitation in Informal Settlements.” Journal of Water, Sanitation and Hygiene for Development, 5 (1) (2015): 64-71. DOI:10.2166/washdev.2014.115. https://search.proquest.com/docview/1930844205.
[10] Ibid.
[11] Ibid.
[12] Robert Tobias et al. "Early Testing of New Sanitation Technology for Urban Slums: The Case of the Blue Diversion Toilet." Science of the Total Environment 576 (2017): 264-272. doi:10.1016/j.scitotenv.2016.10.057. https://www.sciencedirect.com/science/article/pii/S0048969716322239.
23.2015.1007842. http://www.tandfonline.com/doi/abs/10.1080/09603123.2015.1007842.
[14] Tove A. Larson et al. (2015).
[15] Robert Tobias et al. (2017).
[16] Mark O’Keefe. “The Blue Diversion Toilet Finished Its Second Field Test.” Blue Diversion Toilet. June 9, 2014. http://www.bluediversiontoilet.com/blog
[17] Tove A. Larson et al. (2015).
[18] Ibid.
[19] See www.youtube.com/watch?v=VEtKRfXC4-o
[20] Tove A. Larson et al. (2015).
[21] World Bank. (2019).
[22] Ibid.
PHOTO CREDIT: Free use image from Canva Pro.