A waste-based bioplastic was formulated at the University of Saskatchewan, Canada, as a material to absorb orthophosphate pollutants from water resources. The engineered adsorbent pellets perform environmental benefits in addition to water treatment: the bioplastic makes use of eggshell waste and torrefied wheat straw combined with chitosan. As another bonus, the used phosphate-rich pellets can be harvested and distributed as agricultural fertilizer. A sampling of bioplastic pellets designed to absorb phosphate from water. Source: Kristen McEwen

“We’ve made a bioplastic material that functions as an absorbent and it takes phosphate out of water, where elevated levels of phosphate in surface water is a huge global water security issue,” explained the researchers. “You can harvest those pellets and distribute them as an agricultural fertilizer.”

This closed loop system described in RSC Sustainability offers an alternative solution to mining phosphate and instead using the nutrients already present in water sources. The bioplastic-based approach also provides a substitute for products that use plastic coatings to deliver fertilizer to agricultural land, eventually intensifying microplastic pollution.

Laboratory tests demonstrated that a bioplastic containing eggshells, chitosan and 80% torrefied wheat straw content incurred the lowest cost per kg of adsorbent. This material also delivered the highest stability in acidic media.