Human Waste Processor a Potential Solution for Uganda’s Sanitary Problems

Behind the euphemism of “going to the powder room” hides the simple truth of our common human need – relieving ourselves. Similar to the act itself, the disposal of our waste is an unpopular topic that is often hidden behind bathroom doors. However, we can hardly be blamed for our ignorance – in economically developed nations, regular citizens are not generally exposed to waste treatment. In other parts of the world, however, residents are unwillingly familiar with it.

In Uganda’s capital, Kampala, more than 90% of the residents don’t have access to flushable toilets,1 forcing them to resort to either open defecation or the use of public pit latrines. While the latter are a definite improvement, they’re not easy to maintain. It is therefore the goal of sanitary engineers to facilitate this process by devising reliable, easy-to-employ technology, as well as making the waste disposal process more sustainable and environmentally friendly.

Since the public latrines must be located in densely populated areas to encourage their access, it is often difficult to transport necessary cleaning equipment, such as pumps, into the narrow alleyways. Thus, most of the latrines end up abandoned after being filled up, while others are cleared using shovels, or manual scavenging – a highly unhygienic and physically straining process.8

Once the waste has been removed from the latrine, it must be disposed of – in Uganda, this is commonly done in landfills. As these disposals are mostly unsanctioned and not conducted in restricted areas, they further contribute to the potential spread of deadly infections, such as cholera, through ground and water contamination.8

Finding the balance between making the technology effective, as well as feasible, viable and ‘green’, is no easy task. This engineering problem is a worthy challenge, with many scientists looking for inspiration in nature.

An example of one bio-inspired approach is the use of worms for transforming the waste into vermicompost – a type of fertilizer made by worms consuming and passing the organic material through their bodies.2 In a research project conducted by the Oxfam group (a charity confederation), a worm species known as African night crawlers (Eudrilus eugeniae) was used in public latrines along with natural filters, such as sand and charcoal. This method transformed 97-99% of the waste present in the latrines into fertilizer.10 The worms continue reproducing and breaking down the human waste as long as they are maintained at appropriate conditions, which are easy to achieve, with an adequate temperature range of between 5 and 35°C.10 Thus, this method is not only effective, but is also feasible. Additionally, it is viable for poor communities, as all materials used—including the worms—can be sourced locally for free.

However, while the vermicompost produced is safer than waste, it still has to be removed from the latrines using the physically demanding manual scavenging process. Additionally, this method produces effluent, a by-product of waste treatment. Unless properly disposed of, effluent can negatively affect the environment—by introducing an oxygen deficiency for microflora, through excessive nutrient loading—and human health, through additional exposure to pathogens.7 As waste collected from latrines in Uganda is not currently treated, it is likely that the effluent will suffer the same fate. Thus, while using worms is a good temporary solution to the sanitary issue in Uganda, it is not by any means a valid long-term plan.

This is where the Omni Processor comes in. The Janicki Bioenergy Omni Processor manages to not only completely dispose of the waste, but also produce something useful—fresh water and electricity—in the process. First, waste is boiled to produce water vapour, which is then filtered and condensed into drinking water. The dry material is then fed into a furnace, where it is burned. The extreme temperatures (1000˚C) in the furnace ensure that all faeces are turned into pathogen-free ash, which can be used as soil conditioner.3 The energy gained from burning the waste is more than enough to power the steam engine in the processing plant, thus making it run independently of the electric grid, making it sustainable and reliable even in power shortages. The excess energy can be supplied to the local community. Additionally, new jobs will be created in the area, contributing to its economic growth.

Naturally, the processor has its limitations. The machine is large, and therefore cannot be installed close to the latrines, introducing transportation costs for the waste. Initial start-up costs are also a big issue, at approximately £1,000,000,9 making the processor a heavy investment for the Ugandan government, whose entire water and sanitation budget for 2016-2017 was Shs 689,554,000,000, or £140,000,000 (Ministry of Finance, Planning and Economic Development, 2017). Finally, the processor requires a constant input of 10-12 tons of waste to produce electricity and water continuously, meaning that the latrines would have to be cleaned daily, for which they are not designed. However, trash can be used in place of human waste until the latrines are due to be emptied, thus simultaneously solving the issue of garbage disposal in the country.

If this solution were to be implemented in Kampala, it can be argued that its benefits would outweigh the associated issues. The Omni Processor is sustainable, easy to run and maintain, and is safe for environment. Most importantly, it turns one of Uganda’s biggest issues into treasure – jobs, clean water and electricity.

References

1. Baker, M. (2017). The Past and Future of Uganda’s Sanitation: A Photo Essay. [online] PYXERA Global. Available at: https://www.pyxeraglobal.org/the-past-and-future-of-ugandas-sanitation-a-photo-essay/ [Accessed 1 Dec. 2017].
2. Fong J. and Hewitt P. (1996). Worm Composting Basics. [online] Cornell Composting. Available at: http://compost.css.cornell.edu/worms/basics.html [Accessed 1 Dec. 2017].
3. Gates, B. (2015). This Ingenious Machine Turns Feces Into Drinking Water. [online] GatesNotes. Available at: https://www.gatesnotes.com/Development/Omniprocessor-From-Poop-to-Potable [Accessed 3 Dec. 2017].
4. Janicki Bioenergy. FAQ. [online] Available at: https://www.janickibioenergy.com/janicki-omni-processor/faq/ [Accessed 3 Dec. 2017].
5. Janicki Bioenergy. (2017). How it Works. [online] Available at: https://www.janickibioenergy.com/janicki-omni-processor/how-it-works/ [Accessed 3 Dec. 2017].
6. Ministry of Finance, Planning and Economic Development (2017). National Budget Framework Paper FY 2017/18 – FY 2021/22. [online] Kampala: p. 225. Available at: http://budget.go.ug/budget/sites/default/files/National%20Budget%20docs/Final%20BFP%20FY%202017_18.pdf [Accessed 3 Dec. 2017].
7. Naidoo, S. and Olaniran, A. (2013). Treated Wastewater Effluent as a Source of Microbial Pollution of Surface Water Resources. International Journal of Environmental Research and Public Health, [online] 11(1), pp.249-270. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3924443/ [Accessed 2 Dec. 2017].
8. Parker, A. (2017). The Role for Engineers in Addressing the Water and Sanitation Crisis. In: WES Engineering to Change the World. Birmingham: WES.
9. Slavin, T. (2015). How to turn human waste into drinking water – and more. [online] The Guardian. Available at: https://www.theguardian.com/sustainable-business/2015/jan/20/turning-human-waste-into-drinking-water [Accessed 3 Dec. 2017].
10. Watako, D., Mougabe, K. and Heath, T. (2016). Tiger worm toilets: lessons learned from constructing household vermicomposting toilets in Liberia. Waterlines, [online] 35(2), pp.136-147. Available at: http://www.developmentbookshelf.com/doi/ref/10.3362/1756-3488.2016.012 [Accessed 1 Dec. 2017].

About the Author

First year chemical engineering student.

Books