Electricity has been an integral part of everyday life. It has been used to power everything from our lights at home to even our cars. The one place electricity has yet to commonly applied to is in sludge treatment. But a couple of studies are already being conducted to examine its potential.
Researchers led by Professor Patrick Drogui from the Institut National de la Recherche Scientifique (INRS) along with their partners from the European Membrane Institute in Montpellier (IEM) and Université Paris-Est. are investigating the effectiveness of a tertiary process in sludge treatment using electricity.
They are using an advanced electro-oxidation process (EOA) utilising two electrodes to break down non-biodegradable pollutants that remain after secondary treatment. When electricity is passed through the electrodes, hydroxide radicals (OH) are produced. This method removes the necessity of using chemicals being added to the water.
Yassine Ouarda, a Ph.D. student and the first author on the study, decided on using new catalytic electrodes because it produced the largest number of hydroxide radicals and were more affordable.
Drogui believes that the EOA processes are a revolution in the field of wastewater treatment. It is ground-breaking technology in treating wastewater contaminated by refractory pollutants such as pharmaceutical wastes.
The team tested their method on different treatment processes such as conventional, membrane bioreactor, and a treatment process that separates wastewater, including feces, at the source. They specifically targeted paracetamol and acetaminophen residuals for their study.
These drugs were selected because they are the most widely used medications. Ouarda claims that this process can be used for other pharmaceutical compounds as well and is very effective at removing the molecules after biological treatment.
“We observed that the toxicity of the solution increased and subsequently decreased during treatment. This indicates that the toxic molecules themselves are broken down if the reaction continues,” said Ouarda.
Another group of researchers from the School of Chemical and Biomolecular Engineering are also exploring innovative sludge treatment with the use of electrochemical oxidation to clean up complex wastewater. Their goal is to eliminate organic and inorganic contaminants from industrial wastewater during the process of biofuel production.
Julia Ciarlini Jungers Soares, a Ph.D. student in Chemical and Biomolecular Engineering supervised by Dr. Alejandro Montoya, is leading the study into this process.
Just like Drogui’s team, Soares also made use of specialized electrodes to drive the oxidation reactions at its surfaces, turning the organic compounds into harmless gases, ions and minerals. They have likewise found success in eliminating persistent pollutants like pharmaceutical residues as well as pesticides.
Soares and her team have now focused on specific contaminants to better comprehend the chemical dynamics that take place during electrochemical oxidation and are looking for ways to scale up the process.
She admits that finding viable sludge treatment solutions for reuse or disposal is oftentimes very challenging and costly, but she believes that the electrochemical method that they are developing can be readily applied to industries that need to adhere with strict regulations for wastewater disposal, such as pulp and paper processing, wineries, as well as pharmaceutical facilities.
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