Using electricity to break down pollutants left over after wastewater treatment
Advanced electro-oxidation process

Date:
July 9, 2020
Source:
Institut national de la recherche scientifique - INRS
Summary:
Pesticides, pharmaceutical products, and endocrine disruptors are
some of the emerging contaminants often found in treated domestic
wastewater, even after secondary treatment. Researchers have now
tested the effectiveness of a tertiary treatment process using
electricity.



FULL STORY ========================================================================== Pesticides, pharmaceutical products, and endocrine disruptors are some
of the emerging contaminants often found in treated domestic wastewater,
even after secondary treatment. Professor Patrick Drogui of the Institut national de la recherche scientifique (INRS) and his team have tested
the effectiveness of a tertiary treatment process using electricity in partnership with the European Membrane Institute in Montpellier (IEM)
and Universite' Paris-Est.


==========================================================================
The advanced electro-oxidation process (EOA) uses two electrodes to
break down non-biodegradable pollutants that remain after biological
treatment. Electric current is passed through the electrodes, generating hydroxide radicals (* OH), which attack the refractory molecules. The
primary advantage of this method is that it does not require any chemicals
to be added to the water.

"EOA processes are revolutionary in the field of wastewater
treatment. It's pioneering technology for treating wastewater contaminated
by refractory pollutants such as pharmaceutical wastes," said Professor
Patrick Drogui, co- author of the study published on June 18 in the
journal Science of the Total Environment.

The researchers tested new catalytic electrodes. "We have shown that
these electrodes are effective and produce large quantities of hydroxide radicals.

They are also cheaper than the other electrodes currently on the
market, which reduces the cost of the treatment," said Yassine Ouarda,
Ph.D. student and first author on the study.

Versatile Tertiary Treatment Researchers tested the technology on three
types of water coming from different treatment processes: conventional, membrane bioreactor, and a treatment process that separates wastewater, including feces, at the source. They focused on paracetamol, otherwise
known as acetaminophen. "We tested the process on this particular molecule because it's one of the world's most widely used drugs. We have already
tested it at INRS for some 15 different pollutants, as the process can
be used for other pharmaceutical molecules," said Mr. Ouarda.

During partial breakdown of pollutants such as pharmaceuticals, the
by-products can be more toxic than the parent compounds. "We observed
that the toxicity of the solution increased and subsequently decreased
during treatment. This indicates that the toxic molecules are themselves
broken down if the reaction continues," said Mr. Ouarda.

"This work once again confirms that advanced electro-oxidation processes
are good candidates for breaking down drug wastes left behind after
biological treatment," said Professor Drogui.


========================================================================== Story Source: Materials provided by Institut_national_de_la_recherche_scientifique_-_INRS.

Original written by Audrey-Maude Ve'zina. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Yassine Ouarda, Cle'ment Trellu, Geoffroy Lesage, Matthieu Rivallin,
Patrick Drogui, Marc Cretin. Electro-oxidation of secondary
effluents from various wastewater plants for the removal of
acetaminophen and dissolved organic matter. Science of The Total
Environment, 2020; 738: 140352 DOI: 10.1016/j.scitotenv.2020.140352 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200709085301.htm

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