Resnick Fellows Impacting Water Sustainability through Sanitation
Winter 2016 - Written By Resnick Fellow Adam Subhas
As the developing world continues to modernize, we must ask ourselves if the types of infrastructure we rely upon today are the same ones that will exist in China and India in 20 or 50 years. This statement is certainly true for the energy industry. It is also becoming increasingly important for clean water access.
Why does water matter? Isn’t our planet something like 2/3 water? Yes, but only about 2.5% of that is freshwater. Furthermore, most freshwater is currently locked up in glaciers and ice sheets. As a simple calculation, I took the amount of water in rivers and lakes globally (0.3% of global freshwater), divided it into the world’s current population, and again by an estimate of the average human’s daily water footprint**. This gives the number of years of river and lake water remaining, if we were to use it once and let it flow away as waste. The number even surprised me — used this way, our lakes and rivers will only last us about 8 years!
Besides rivers and lakes, there is a large amount of groundwater that we have access to. We also have wastewater treatment plants and other ways to recycle water. But this calculation underscores the extreme importance of wastewater recycling as our population continues to increase. For example, about 4.2 billion people worldwide do not have access to proper sanitation, and UNESCO estimates that 2/3 of the world’s population will suffer from water scarcity by 2025.
What can we do to improve water quality for the developing world? Professor Hoffmann’s Group at Caltech is developing a sustainable solution to wastewater treatment that promises sanitized water without the need for major sewage infrastructure and large, centralized wastewater treatment plants. This decentralized approach uses solar energy coupled with an in-line electrode system to break down organic matter at its source. The system is part of the toilet itself, and can completely decontaminate human waste in 4 hours with energy provided by solar panels. Water treated this way is disinfected, and relatively depleted of macronutrients and water-borne pathogens. While it isn’t completely safe for human consumption, it is ideal for recycling as flushing water or for other “gray water” uses. It is also much safer to discharge into the environment.
Justin Jasper, a Resnick postdoctoral scholar, is interested in fine-tuning this electrochemical system, characterizing what the electrodes are doing and how that affects the fate of contaminants in the system’s outflow. Specifically, he is interested in phosphate and organic chemicals. “As we better understand what we want the system to do, we can more efficiently design electrodes to perform this chemistry,” Justin explained. Deeper chemical understanding will help the team develop a better and less expensive process.
Of course, a wastewater treatment system isn’t very effective if it only works in the lab. The Hoffman group has several field systems currently operational in India and China. Operation in real-world conditions often leads to technical problems which can be difficult to diagnose and fix by local engineers and users. "The seemingly state of the art method for repairing high tech solutions to problems in the developing world is to fly a tech from the developed world out out or to let the system turn into dust. This was crazy to me,” said Cody Finke, a Resnick graduate fellow working on the project. Cody is instead developing an inexpensive way to monitor and fix these field units using a simple cellphone-based platform. This system will allows for laypeople to identify the broken part, order a replacement, and perform the maintenance using only a screwdriver and a cellphone. The development of this plug-and-play engineering will be crucial to having these rather complicated systems take hold in the developing world.
This multi-pronged approach at point-source wastewater treatment is just one example of how water sustainability issues are being tackled at Caltech. Through developing the chemistry in the lab, and ensuring a simple product that is easily maintained, this technology is helping to reduce wastewater contamination and improve the water quality for many in the developing world who lack access to quality water infrastructure.