Scientists Used Stale Bread to Produce Drinking Water

Usually we’d say the best thing to do with stale bread is to turn it into breadcrumbs. However, one group of scientists is changing how we think about a loaf that’s past its prime.

In February, engineers from Saint Vincent College, the University of Pittsburgh, and the University of Pennsylvania revealed the findings of their research, which discovered that bread could be a valuable tool for desalinating — aka removing the salt from — water to make it drinkable.   

Published in the peer-reviewed, open-access journal Royal Society Open Science, the study details how scientists used stale bread (specifically Pepperidge Farm whole-wheat bread) to more sustainably produce carbon electrodes. The high carbon content of bread allowed researchers to transform it into carbon electrodes, which are electrical conductors that can be used to desalinate water.

This study was conducted by graduate students David Bujdos and Zachary Kuzel, alongside Dr. Adam Wood, who has previously published a paper on the potential for turning stale bread into carbon electrodes.

The researchers tested two strategies for developing their carbon electrodes from stale bread. The first method involved using a 3D-printed mold to stamp the bread into the desired shape, then heating it in a furnace to a very high temperature — 800°C or 1472°F — for an hour, while under a flow of nitrogen gas, until it formed a solid carbon electrode.

The second method started with combining bread and water in a blender, molding the resulting mixture into the requisite shape for the electrode, and then popping it in an 800°C, oxygen-free oven — a heating process known as pyrolysis. 

While both methods had their merits, the team noted that the 3D printing strategy created detailed shapes, but the soggy bread mixture yielded sturdier and more precise end products, giving the latter a slight edge as the winner. The best part? Both methods worked well without calling for the chemicals or expensive ingredients that are required to make many other carbon electrodes.

According to Tech Xplore, the researchers hope to continue refining their work and figure out how to mass-produce the product to create low-cost desalination systems to assist in delivering fresh water to people across the globe — an issue of growing concern considering that nearly one in three people in the world do not have access to clean drinking water, according to the United Nations International Children’s Emergency Fund (UNICEF) and World Health Organization.

Utilizing stale bread also helps to eliminate a major source of food waste. According to a 2021 study at the University of Vaasa, the world produces some 100 million tons of bread a year, and an estimated 900,000 of those tons go to waste. That works out to about 24 million slices of bread thrown out per day.

Besides wasting valuable food and the resources used to produce it, tossing bread into a landfill has environmental implications. Research published by the open access journal Molecules explains that “bread waste presents a serious environmental impact. Considering the fact of [bread] being organic biogenic waste, studies have shown that bread is responsible for gas emissions in the form of carbon dioxide or even methane.”

There’s even more great news. Beyond its use in making carbon electrodes, research published by peer-reviewed journal Trends in Food Science and Technology reveals that stale bread can be repurposed to make everything from textiles and graphene — a carbon-based material used for electronics and other devices — to beer.

It’s rare to find a win-win-win scenario, but one that involves providing clean drinking water, reducing food waste, and making the most of precious bread sounds like just that to us.