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Monday, February 12, 2024 at 11:53 p.m.

New low-cost materials to purify wastewater

A scientific team from Chemical and Environmental Engineering Group of the URJC has carried out a study, in collaboration with Repsol, based on hydrothermal carbonization techniques of organic waste.

Writing / Irene Vega

In the research carried out by the Chemical and Environmental Engineering Group (GIQA), carbonaceous materials were prepared from the solid obtained through the hydrothermal carbonization (HTC) treatment. Hydrothermal Carbonization) of organic waste. This technique is a thermal process that involves the conversion of organic matter into carbonaceous materials under conditions of high temperature and pressure in the presence of water. During the process, the organic compounds present in the materials decompose, leading to the formation of a carbonaceous residue, known as hydrochar, which has properties similar to coal and can be used in multiple applications. “This process is considered a promising option for the management of organic waste and the obtaining of carbonaceous materials with diverse applications. However, to achieve a highly developed porous structure in these materials, physical and chemical activation processes at high temperatures are required,” explains Isabel Pariente, researcher in the GIQA group and co-author of the article published in Catalysis Today magazine.

In this work, a hydrochar was used from the hydrothermal carbonization of anaerobic digestion sludge - a process by which microorganisms decompose biodegradable material in the absence of oxygen - from a wastewater treatment plant. “However, during the HTC processes, an aqueous effluent is generated, which is potentially toxic and must be treated appropriately,” explains the URJC researcher. For this, a catalytic wet oxidation process has been proposed. During this process, free radicals can be formed, such as hydroxyl radicals, which are highly reactive and can efficiently attack and degrade the organic matter present in the effluents. “Carbonaceous catalysts, such as hydrochar, can improve the efficiency of these processes by providing active centers for adsorption and generation of free radicals. Additionally, these catalysts are often considered attractive options due to their sustainability and ability to reduce unwanted byproducts.”

The results obtained suggest that these low-cost materials could be promising for the treatment of HTC effluents using the hydrochar obtained from the same waste treatment, therefore closing the cycle towards a circular economy.

This research is part of the UPGRES project, whose main objective is to investigate the integration of different transformations through thermochemical and catalytic biotechnological routes, including innovative technologies, such as the production of microalgae or hydrothermal carbonization. Furthermore, to minimize the environmental impact, the project addresses the decontamination of final effluents through processes based on oxidation.