Loughborough University researchers demonstrate coffee waste use to clean water

In the UK, two new research publications from experts at Loughborough University have demonstrated how coffee waste can be used to clean water. Published in Biomass and Bioenergy and Clean Technologies, the studies showcase how coffee waste could be used effectively to filter heavy metals, such as lead, copper and zinc, from water. 

Coffee is one of the most widely consumed beverages worldwide. In 2021–22, global coffee consumption exceeded 176 million bags (around 60kg per bag), marking a notable rise from approximately 167 million bags in the previous year. The growing global consumption generates substantial waste, particularly spent coffee grounds (SCGs), a byproduct rich in organic matter. SCGs are porous, plant-derived materials that have excellent potential as adsorbents that could prevent coffee from going to waste. Various other adsorption materials have also been tested for filtering water and metal ion removal, including resins, clay, rice husks, banana peels, and tea leaves. 

By heating used coffee grounds, taken from Loughborough University’s Edward Herbert Building cafeteria, the research team, in collaboration with Banaras Hindu University (India), produced highly porous biochar, a carbon-rich material, often used to improve soil quality.  After optimising the temperature and duration of the heating, they could remove up to 98% of lead from water, with the biochar holding 4.9 mg of lead per gram.  

The study by researchers at Loughborough University demonstrated that the raw coffee waste, also collected from the Edward Herbert Building cafeteria, can be used directly without any further processing to remove heavy metals (eg. copper and zinc) from water at low metal concentrations. The new research also demonstrates that coffee waste can be used in combination with other materials (eg. rice husk) to achieve heavy metal treatment.