High school students from Barrie Middle and Upper School in Silver Spring, USA, are tackling the problem of lead pollution in drinking water. They have designed a cheap, reusable cartridge filter that removes this toxic heavy metal from tap water and warns when the chemical cartridges it uses need to be refreshed.
The problems people have with drinking water supplied by lead pipes are already well known. The plight of the residents of Flint, Michigan is a tragic example. Exposure to lead from drinking water can lead to a host of medical problems, ranging from cardiovascular complications to cognitive and reproductive problems.
High school students have now joined efforts to protect people from this toxic metal by designing a simple device that can clean it from tap water.
Filters printed at home
“A few years ago, I saw a video of a Michigan woman turning on her water faucet, and she came out brown,” says Rebecca Bushway, a Barrie science teacher and lead researcher on the project. “It got me thinking – because there really is no safe level of lead in drinking water, wouldn’t it be nice to have a water filter that could tell you that your water is contaminated, long before it turned brown from lead?”
Lead has always been the metal of choice for piping, due to its ease of processing and apparent resistance to water. In fact, it has been used for this role since the days of the Roman Empire. Metal and use were so intertwined that to this day we inherit the title “plumber” from the Latin word for “lead”: plumbum.
Many homeowners in the United States have replaced their plumbing with lead pipes for safer options, but millions of homes still retain their old plumbing. This is especially true for residences located in low-income and less affluent areas, whose residents often cannot afford the major cost of such an undertaking. This leaves countless families across the country – and around the world – exposed to harmful lead contamination in their water.
Lead contamination of drinking water occurs in areas where the water has high acidity or low mineral content, or where demand is high, which increases the flow of water through the pipes. These factors can cause lead to dissolve or flake off in the water, resulting in a dark tint or visible particles in the liquid.
In an effort to keep them safe, Barrie Middle and Senior School students designed an inexpensive filter to remove lead from drinking water. This is a cheap-to-produce faucet accessory that comes with a replaceable cartridge containing the actual filter material – unlike other commercially available filters, which are a one-off deal. The cartridge is made of biodegradable plastic and even tells the user when it needs to be replaced by turning tap water yellow.
The filter is much cheaper to produce and install, while being much more compact than currently available filters. Students also consider its ability to show that the filter cartridge is worn out and needs refreshing to be a big improvement over current systems, as it helps alert users when water flowing from their tap may not be in use. safely.
The project began when Bushway asked his high school chemistry class if they thought they could make a filter similar to those used for camping using inexpensive components to remove lead from water. Students began working on the project in 2020 to keep pace with schoolwork during the COVID-19 pandemic. Most of the work through 2021 was done virtually and focused on designing the accessory that would connect the filter to a faucet. Back in class, they started 3D printing the cartridge cases (which are 3 inches / 9 cm tall) and filling them with a mixture of calcium phosphate and potassium iodide powder.
“Calcium phosphate first binds to lead dissolved in water to form lead phosphate and free calcium. Calcium, which is harmless, ends up in the water and the lead phosphate remains in the filter says Bushway.
The end product, lead phosphate, is an inert solid and remains trapped in the filter by a nylon screen attached to its bottom. Once the calcium in the cartridge has been used up, the remaining lead in the water now reacts with the potassium iodide, causing the water to turn yellow.
In the future, the students aim to add a small spectrometer with a single wavelength LED to the bottom of the cartridge. This device will check for the presence of lead in the water and alert the user even before the yellow color is detectable to the human eye. Their end goal is to make the filters cost less than $1 each.
“Ultimately, this experiment showed the students that they can make a difference to someone, and there are problems they can solve with science,” Bushway says.
This research was presented at American chemical society (ACS) Spring 2022 meeting, with the highlights of the presentation to be uploaded on The ACS Youtube page.