Food waste cleans water, gathers metals for re-use

A team of researchers from Mexico and Spain have found a way to use waste citrus peel to clean water with a method that also gathers valuable metals for reuse.

Researchers from Spain’s Universidad de Granada and Mexico’s Center for Electrochemical Research and Technological Development and Center of Engineering and Industrial Development have found a way to put the more than 38 million tons of annual global citrus peel food waste to use. After treating orange and grapefruit peels with an Instant Controlled Pressure Drop, the fruit waste gains adsorbent properties. Adsorbent properties are distinct from absorbent properties. Adsorbing holds a material onto the surface of another object rather than soaking it up.

When treated peels were packed into filter columns like those currently used in wastewater treatment plants, the new materials removed organic pollutants as well as gathered metals. And by adsorbing the metals, they can be harvested for future reuse. In tests, the cleaning rates of the peel filters were high enough to be used commercially, ideally leading to eventual replacement of the commonly used activated carbon filters.

Water is a precious, finite resource, which is why sustainability projects focus on myriad aspects of its care. Synthetic DNA is being used to find sources of contamination much more quickly than traditional methods have allowed, and new ways of gathering it, like this method for turning fog into potable water, are helping communities living in arid regions. How else could waste products be used to improve a process as well as contribute to additional levels of sustainability?