A biofilter made from pumpkin peels could capture almost 100% of the lead present in water contaminated by this heavy metal
The millions of pumpkins that need to be disposed of the day after Halloween could have a useful second life for the environment. Indeed, a study published by a team from Laval University in theInternational Journal of Environmental Science and Technology suggests that pumpkin peel - like that of three other fruits - could provide valuable environmental services thanks to its ability to capture heavy metals such as lead.
This was demonstrated by the team led by Seddik Khalloufi, professor in the Department of Soils and Food Engineering and researcher at Université Laval’s Institute of Nutrition and Functional Foods. "Existing techniques for removing heavy metals from wastewater or soil are costly and often require skilled personnel. There is a demand for more effective and economical techniques," notes Professor Khalloufi.
Initially, the aim of his team’s work was to find active ingredients with functional properties, such as health benefits, in plant waste generated by the food industry. "The idea is to add these active ingredients to foods such as yogurts or certain drinks," explains the professor. Along the way, we found, somewhat by accident, that some fruit peels were able to adsorb heavy metals such as lead."
Khalloufi’s team focused on three fruits whose inedible skins represent a high percentage of their weight. These were watermelon (30%), banana (38%) and yellow melon (56%). "We also added pumpkin because we wanted to have a fruit grown in abundance in Quebec. Its peel represents only 7% of its weight, but given the number of pumpkins that are thrown away after Halloween, this represents a considerable biomass," points out the researcher.
To assess the lead uptake capacity of these fruits, the researchers first transformed their peel into powder. They then placed each of these powders in solutions containing a known concentration of lead. "After 5 minutes of contact, the powders from each of these fruits had adsorbed 99% of the lead present in the water", summarizes Professor Khalloufi.
Given their high efficiency, these powders could be used to make biofilters to remove lead, and probably other heavy metals, from wastewater or water contaminated by environmental spills. "The heavy metals captured by these biofilters could be recovered and used in industrial processes," he points out.
Heavy metals may not be the only problematic compounds that could be captured by these powders, continues the researcher. "We plan to evaluate their effectiveness with pesticides, antibiotics and hormones."
"Our results show not only that these plant wastes can be valorized, but that they are sufficiently effective for us to consider the possibility of them replacing conventional synthetic adsorbents," he believes. What remains to be done, of course, is to scale up processes using these powders and demonstrate their economic viability."
Thanks to a grant from the Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec, Khalloufi’s team now intends to study the effectiveness of Quebec native berry remains generated by the food industry in adsorbing and removing heavy metals from contaminated water.
The signatories of the study, published in theInternational Journal of Environmental Science and Technology, are Zarifeh Raji, Robercia Maleka, Ahasanul Karim, Antoine Karam, Mohammed Aider and Seddik Khalloufi.
