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Spotlight on Young Researchers: Constructed wetlands – a new approach to treating wastewater

Pharmaceuticals and personal care products (PPCPs) are a significant contaminator of surface water: They are not sufficiently removed from wastewater in treatment plants, as this requires additional and costly methods. Researchers are working on a solution that could save up to one third of drinking water in Luxembourg alone, while reducing costs and environmental effects.

“A proposed solution is the implementation of constructed wetlands (CWs) for the on-site households’ greywater treatment. Greywater is the household’ wastewater, excluding the toilet fraction, which could be after being treated, reused for toilet flushing. In Luxembourg, around 645,000 inhabitants could benefit from this solution, saving at least 27% of potable water, reducing costs in WWTPs and environmental effects due to the PPCPs removal at the source,” explains Fernanda Cristina Muniz Sacco, Agronomist Engineer with MSc in sustainable development with focus on energy and environment.

Promising pilot studies

Researchers have conducted lab and pilot scale studies of these constructed wetlands (CWs), which has shown their efficiency in removing micropollutants such as pharmaceuticals and personal care products (PPCPs), both from wastewater treatment plants effluent (WWTPs) as well as from greywater (on-site treatment). 

Constructed wetlands could be implemented as an interesting solution in WWTPs to be complainant with future effluent requirement and water reuse, or in sustainable buildings, making it possible to control pharmaceuticals and personal care products remnants at the source.

But: More research into the pollutant removal mechanisms – a combination of adsorption on soil material, biological degradation by bacteria and plant uptake– is needed, with the design and dimensioning of constructed wetlands also requiring more in-depth investigation before it can be up-scaled to be integrated to a city’s water services.

More insight into pollutant removal mechanisms needed

“There are significant challenges in the widespread adoption of constructed wetlands (CWs): Despite their demonstrated effectiveness, we still do not understand enough how plants and microorganisms contribute to the pollutants’ removal. We need to study this in depth to design CWs with the right dimensions and conditions that foster pollutants removal efficiently and effectively.”
Fernanda Cristina Muniz Sacco Agronomist Engineer with MSc in sustainable development with focus on energy and environment.

Research projects such as the one agronomist engineer Fernanda Cristina Muniz Sacco is working on as part of her PhD, could overcome the knowledge challenge. Still more, challenges lie ahead: The way buildings are currently constructed, combined with people’s habit about water consumption is still in the way of the challenge being solved.

“People are not used yet to treat locally wastewater for the purpose of reuse. Therefore, policies and legal framework need to be redefined and campaigns should promote water reuse.”

A closer look at the constructed wetlands before upscaling

In her PhD project, Fernanda studies the viability of constructed wetlands for the removal of personal care products from greywater, by using different admixture substrates and biochar, produced in the circular economy perspective, from plants residues and from sewage-cellulose.

After gaining insight into the bacterial community involved in the pollutant removal, the next step is to design a greywater treatment technology fit for purpose, based on quality standards for water reuse in sustainable buildings. In addition to the drinking water savings, wastewater treatment plants could also benefit from the decreased micropollutants load due to the removal at the source.

And there is another benefit that could come out of urban wastewater:

“During my Master thesis, we proved that biodiesel could be produced from accumulated lipids in sewage, which besides applying circular economy concepts in WWTPs, fossil diesel consumption could be reduced.”

Fernanda Cristina Muniz Sacco, Agronomist Engineer with MSc in sustainable development with focus on energy and environment. She is currently a PhD candidate at the University of Luxembourg’s Faculty of Science, Technology and Medicine, supervised by Prof Dr Joachim Hansen. She is also co-supervised by Prof Dr Paul Wilmes from Luxembourg Centre for Systems Biomedicine (LCSB).

Fernanda at the FNR outreach activity ‘Researchers at School ‘(Chercheurs à l’école) in 2022.


Describing her research in one sentence

“Removal of personal care products from microbial processes in constructed wetlands for grey water recycling in sustainable buildings.”

Why she chose this path

“My work in R&D started with my bachelor degree in Agronomy Engineering, focused on sustainable food production and renewable energy, in which I worked for many years in Brazil. What drove me to the University of Luxembourg was the possibility to continue with sustainable development for urban water management.”

On her love for science

“Besides believing that research is the base of the society development in general, the work environment is very dynamic, and I am always learning new things and developing new skills. Moreover, working with sustainable solutions to improve people’s lives and the quality of environment is very rewarding.”

Mentors with an impact

“The professors of my bachelor (in Brazil) and master (in Luxembourg and Liege), and now my PhD supervisor (Prof. Joachim Hansen), made and are making a significant positive impact in my research career path. Besides inspiring me, they believed in me and gave me the opportunity to follow my path.”

On choosing Luxembourg for her research

“The research was not the reason I came to Luxembourg, but the reason I have been living here for almost 8 years. My path as a researcher in Luxembourg started with my Master degree at the UniLu, in which I participated in interesting projects, such as the biodiesel production from sewage-lipids, which besides being the topic of my master thesis, lead to an open access publication in the journal Bioresource Technology where I appeared as the first author. It continues with my current PhD which has been developed with the received grant from the FNR.. The multicultural environment is one of the best things of working here!”

Where she sees herself in 5 years

“In 5 years, or after finishing my PhD study, I see my myself following a post-doctoral career in some other subjects related to sustainable development and environment, which have always been part of my professional path.”

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