Removal of Metals and Emergent Contaminants from Liquid Digestates in Constructed Wetlands for Agricultural Reuse

41 Pages Posted: 19 Dec 2023

See all articles by Pau Porras-Socias

Pau Porras-Socias

affiliation not provided to SSRN

Maria Paola Tomasino

affiliation not provided to SSRN

Joana P. Fernandes

affiliation not provided to SSRN

Alexandre B. De Menezes

University of Galway

Belén Fernández

affiliation not provided to SSRN

Gavin Collins

affiliation not provided to SSRN

Maria João Alves

affiliation not provided to SSRN

Ricardo Castro

affiliation not provided to SSRN

Carlos R. Gomes

affiliation not provided to SSRN

C. Marisa R. Almeida

affiliation not provided to SSRN

Ana Paula Mucha

affiliation not provided to SSRN

Abstract

Vertical subsurface flow constructed wetlands were set up as a low-cost decentralised wastewater treatment technology to treat the liquid fraction of digestate with metals, antibiotics, and antibiotic resistance genes, to allow its reuse in irrigation. Twelve lab-scale planted constructed wetlands were assembled with gravel, light expanded clay aggregate and sand, testing four different treating conditions (liquid digestate spiked with oxytetracycline, with sulfadiazine, or with ofloxacin or without dosing) during four months. All influents and effluents were monitored focusing on physicochemical parameters, the microbial communities dynamics and antibiotic resistance genes removal. Systems removed between 69 and 99.8% of organic matter, ammonium, nitrate, nitrite, and phosphate ions with no significant differences between the presence or absence of antibiotics. The removal of Fe, Mn, Zn, Cu, Pb and Cr reached over 82% in all treatment cycles. The treatment was also successful in removing oxytetracycline, sulfadiazine and ofloxacin over 99%, and in decreasing the intl1, tetA, tetW, sul1 and qnrS gene copies. Nonetheless, after 3 months of ofloxacin dosing, the qnrS gene started being detected in these systems. The microbial community diversity in liquid digestate presented significant changes after the treatment in constructed wetlands with a decrease in the initial Firmicutes dominance, but with no clear effect of the antibiotics on the microbial community structure. Regarding the potential pathogenic genera, removals above 85% and 94% were observed for Streptococcus and Clostridium, respectively. Results suggest that vertical subsurface flow constructed wetlands were a suitable technology for treating the liquid digestate to reuse it in irrigation agricultural systems, contributing to the circular bioeconomy concept. However, a more profound understanding of effective wastewater treatment strategies is needed to avoid antibiotic resistance genes dissemination.

Keywords: Constructed wetlands, metals, Antibiotics, Antibiotic resistance genes, anaerobic digestion effluent, Sparganium erectum

Suggested Citation

Porras-Socias, Pau and Tomasino, Maria Paola and Fernandes, Joana P. and De Menezes, Alexandre B. and Fernández, Belén and Collins, Gavin and Alves, Maria João and Castro, Ricardo and Gomes, Carlos R. and Almeida, C. Marisa R. and Mucha, Ana Paula, Removal of Metals and Emergent Contaminants from Liquid Digestates in Constructed Wetlands for Agricultural Reuse. Available at SSRN: https://ssrn.com/abstract=4668623 or http://dx.doi.org/10.2139/ssrn.4668623

Pau Porras-Socias (Contact Author)

affiliation not provided to SSRN ( email )

No Address Available

Maria Paola Tomasino

affiliation not provided to SSRN ( email )

No Address Available

Joana P. Fernandes

affiliation not provided to SSRN ( email )

No Address Available

Alexandre B. De Menezes

University of Galway ( email )

Belén Fernández

affiliation not provided to SSRN ( email )

No Address Available

Gavin Collins

affiliation not provided to SSRN ( email )

No Address Available

Maria João Alves

affiliation not provided to SSRN ( email )

No Address Available

Ricardo Castro

affiliation not provided to SSRN ( email )

No Address Available

Carlos R. Gomes

affiliation not provided to SSRN ( email )

No Address Available

C. Marisa R. Almeida

affiliation not provided to SSRN ( email )

No Address Available

Ana Paula Mucha

affiliation not provided to SSRN ( email )

No Address Available

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