Proposal Requirement 3 Example: Water Purification

Writer: Jana Chan

Instagram: @jana.chan_


Current Solutions and Their Insufficiencies

Given that 2.2 billion people lack access to safe drinking water, there have certainly been many solutions developed to not only improve access to clean water but to also ensure that there will be clean water available for future generations (United Nations [UN], n.d.). One way this has been achieved is through purifying already-existing sources of potential drinking water, such as human waste, seawater, and dirty water.

Recycling water from human waste and sewage is one method that seems to be very promising. After all, since humans produce 290 million tons of feces and 1.98 million liters of urine a year, it seems to be an amazing solution for two problems: one of excess waste and one to provide a basic necessity (Kluger, 2015). To do this, an Omni Processor, built and designed by Janicki Bioenergy, converts sewage sludge into water, electricity, and fertilizer (Gates, 2015; Tam, 2015). It begins by boiling the sewage sludge and then collecting the water vapor that is produced. The water vapor is then purified into drinking water. To create electricity, the already dry and boiled waste is burned to create steam. The steam is collected and used in a generator that can power both the Omni Processor and send its excess electricity elsewhere for other uses (Tam, 2015). Systems like these have already been implemented in places such as Singapore and Senegal, where Janicki Bioenergy is studying how to best connect this machine with local communities (“10 Clean Water,” 2016; Gates, 2015). This solution is perfect as it is not only self-sustaining (the electricity produced is reused to power the machine) but it also prevents any human waste from contaminating other clean water sources. Though the idea is very simple, the Omni Processor is still quite complex and expensive enough that it is not widely available yet; more research and studies will need to be done.

Another encouraging solution, that is more widely used than the Omni Processor, is the process of desalination. With such a large abundance of water in the world’s oceans but 99% of it undrinkable, desalination removes salt and other mineral components from this seawater. This purification process is typically done in over 16,000 desalination plants worldwide (Doyle, 2019). Many countries see its advantages as the largest desalination plant in the world, located in Saudi Arabia, produces 273 million gallons of drinking water per day and in Israel, a quarter of its clean water supply comes from desalination (“10 Clean Water,” 2016). This method, already proven to be effective using reliable technologies, greatly benefits the agriculture industry as well. However, desalination—although it has improved many people’s access to safe drinking water—also has negative consequences. A 2019 United Nations-backed study examined the impacts of desalination on the environment and found that the brine, with 5% salt composition and other toxins such as copper and chlorine, used in desalination can “accumulate in the environment” (Doyle, 2019). For reference, seawater only contains about 3.5% salt (Doyle, 2019). This means that any habitats or bodies of water near desalination plants could experience drastically lower oxygen levels as a result of this brine, causing severe ecological impacts on the shellfish, crab, and other wildlife that live there.

Finally, solar stills (figure 1) have been another state-of-the-art development to arise as a potential solution. This simple process harnesses the natural energy of the sun to purify water (Sherwood, 2017). Dirty water (or in the figure some seawater) flows into a basin with a slanted piece of glass above it. This allows solar rays to enter the system but does not allow any heat to escape. The bottom of the basin is often painted in black to better absorb the energy of the sun. As the dirty water evaporates due to its increase in temperature from solar energy, the liquid water is converted into steam. This leaves anything that is not pure water, such as minerals or bacteria, in the basin below and ensures that the resulting water is pure and safe for human consumption. When the steam hits the glass ceiling, the water condenses to create pure water droplets. It rolls down the glass and is collected in a separate tank.

Figure 1. A schematic design of a simple solar still. Retrieved November 28, 2020, from

Because of this, a solar still has the “dual capacity to desalinate and decontaminate water” (“10 Clean Water,” 2016). Additionally, pH levels of clean water from solar stills stay balanced, unlike the water from the boiling process used by commercial water-bottling plants, because this water has been purified naturally (Sherwood, 2017). The solar still has many benefits ranging from low installation costs, easy operation, and little to no negative impacts on the environment as harmful byproducts or toxic gases seem to be produced. The process is so simple that it will be easier to implement in rural areas. However, one limitation to the solar still is the climate. Solar energy will only be available during the day and in regions with inadequate sunlight, little water can be evaporated and thus this method cannot be heavily relied on. Furthermore, this process is not very efficient. The rate of distillation is too slow and not sufficient for large consumption, with only about 6 liters of water produced on a sunny day (Safe Drinking Water Foundation, n.d.).

Each of the technologies mentioned above has its strengths and weaknesses but all work to purify existing sources of water. Therefore, I propose the following technology that combines their strengths while mitigating their insufficiencies.


Overall, the author does a good job of explaining the current solutions and their insufficiencies. To ensure that her solution is not too similar to other pre-existing solutions, the author does well in acknowledging other methods that have already been developed. She describes the advantages and disadvantages thoroughly, especially in connecting these to current events or limitations. Additionally, this section serves as the perfect context for her solution because it seems to be based on some pre-existing solutions. Her use of a diagram to illustrate how solar stills are used helps to organize her thoughts and was an aspect that enhanced her proposal. She also writes in a professional tone with proper APA citations and a reference page properly formatted.

One area that she could improve in is more description of the Omni Processor and desalination process works. She focuses too much on its advantages and its insufficiencies and would’ve benefitted from more balance.


10 Clean Water Solutions For Developing Countries. (2016, April 11). Borgen Magazine. Retrieved

November 28, 2020, from

Doyle, A. (2019, January 14). Too much salt: Water desalination plants harm environment: U.N.


Kluger, J. (2015, November 3). How Poop Can Be Worth $9.5 Billion. Time Magazine.

Gates, B. (2015, January 5). This ingenious machine turns feces into drinking water. Gates Notes.

Safe Drinking Water Foundation (n.d.). Solar Water Distillation.

Sharshir, S. W., Yang, N., Peng, G., & Kabeel, A. E. (2015). A schematic design of a simple water still

[online image]. Retrieved November 28, 2020 from


Sherwood, C. (2017, April 24). How Does a Solar Still Work? Sciencing.

Tam, R. (2015, January 6). WATCH: This machine turns human waste into water. PBS.

United Nations. (n.d.). Water.