Two students made compostable water filters from food waste
Pratt Institute graduate students Charlotte Böhning and Mary Lempres of Studio Doppelgänger created Strøm, a compostable water filters made from food waste. They’re a carbon filter made without fossil fuels, using kitchen scraps. You can use Strøm filters as substitutes for Brita cartridges, or add purifying filter sticks to bottles or glasses of water. There’s even a self-cleaning pitcher.
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How does it work? These filters use activated charcoal, but instead of sourcing them from petroleum, the source is a form of natural biochar. It is mixed with natural resins to be shaped like a thermoplastic. The composite acts as a filter or vessel. At the same time, it opens up a new horizon of options for water filtration and storage. Additionally, it reduces the need for single-use plastic filters that end up in landfills by the 100 million every year.
Furthermore, manufacturing is a simple process with Strøm filters. Böhning and Lempres burned banana peels, sheep bones and other waste from their kitchen, local farms and restaurants in a kiln. This “pyrolysis” process prevents the carbon in the biomass from forming carbon dioxide during combustion. Instead, it turns it into a porous absorbent char that stores away the carbon from the food rather than release it into the atmosphere. Sequestering carbon was one of the main goals of the project. Even when these filters finally reach the landfill, they will continue to store carbon. It won’t produce methane like food waste does.
Biochar and bee propolis are combined with tree resins to create these flexible shapes that can be casted, injected or molded to form cartridges or actual Strøm water pitchers. The final products claim to outperform traditional filters and work to filter several substances that don’t react to activated carbon. The biochar is magnetized in a ferrous salt bath to draw out heavy metals from water. Meanwhile, animal bones in the char filter out fluoride.
The propolis and tree resin prevents bacterial buildup and act as a binder. It’s brilliant, really. Bees use propolis to mummify the carcasses of hive intruders to stop the spread of disease. This means propolis can be used for a number of antimicrobial, antiviral and antifungal applications.
As a result, the filters decompose in soil in about a month. Plastics often take 11 generations to break down while releasing polluting and hormone-disrupting chemicals into the water and soil. Biochar, on the other hand, can be used as a fertilizer or as a carbon sink.