Microbiological and physicochemical quality enhancement of treated wastewater using raw and chemically modified clays from Sidi Bouzid region, Tunisia

Hakima Gharbi-Khelifi; Habib Jmii; Mohamed Mosbahi; Samiha Hamdi; Rawand Hamdi; Jihen Brahmi; Slim Loukil; Mohamed Chamkha; Sami Sayadi; Mahjoub Aouni; Ana Barreiro; Maria J Fernández-Sanjurjo; Avelino Núñez-Delgado; Esperanza Álvarez Rodríguez

doi:10.1016/j.envres.2023.117391

Microbiological and physicochemical quality enhancement of treated wastewater using raw and chemically modified clays from Sidi Bouzid region, Tunisia

Environ Res. 2023 Dec 15;239(Pt 2):117391. doi: 10.1016/j.envres.2023.117391. Epub 2023 Oct 16.

Affiliations

¹ LR99-ES27, Faculty of Pharmacy of Monastir, University of Monastir, Avenue Avicenne, 5000 Monastir, Tunisia; Department of Biotechnology, Faculty of Science and Technology of Sidi Bouzid, University of Kairouan, 9100 Sidi Bouzid, Tunisia. Electronic address: khelifi_hakimaa@yahoo.fr.
² LR99-ES27, Faculty of Pharmacy of Monastir, University of Monastir, Avenue Avicenne, 5000 Monastir, Tunisia.
³ Laboratory of Georessources CERTE, Technopole Borj Cedria, Tunisia.
⁴ Department of Biotechnology, Faculty of Science and Technology of Sidi Bouzid, University of Kairouan, 9100 Sidi Bouzid, Tunisia; Department of Soil Science and Agricultural Chemistry, Engineering Polytechnic School, University of Santiago de Compostela, 27002 Lugo, Spain.
⁵ Department of Biotechnology, Faculty of Science and Technology of Sidi Bouzid, University of Kairouan, 9100 Sidi Bouzid, Tunisia.
⁶ Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, Sfax University, PO Box 1177, 3018 Sfax, Tunisia.
⁷ Biotechnology Program, Center for Sustainable Development, College of Arts and Sciences, Qatar University, Doha 2713, Qatar.
⁸ Department of Soil Science and Agricultural Chemistry, Engineering Polytechnic School, University of Santiago de Compostela, 27002 Lugo, Spain.

PMID: 37852463
DOI: 10.1016/j.envres.2023.117391

Abstract

Environmental discharge of wastewater represents a source of chemical and biological pollutants. This study firstly evaluates the microbiological and physicochemical quality of treated wastewaters collected from two wastewater treatment plants (WWTPs) located in two different Tunisian cities namely Sidi Bouzid (SB) and Gafsa (G). Then, the capacity of three raw and acid/base-activated local clays to enhance the quality of wastewaters was assessed. The results indicate that the quantities of enteric bacteria (oscillating from 1.381 × 10³ to 1.4 × 10⁸ CFU/100 mL), fungi (between 1.331 × 10³ and 1.781 × 10⁴ CFU/100 mL), as well as SARS-CoV-2 (between 4.25 × 10³ and 5.05 × 10⁵ CFU/100 mL) and Hepatitis A virus RNA (form 4.25 × 10³ to 7.4 × 10⁴ CFU/100 mL) detected in effluent wastewaters were not in compliance with the Tunisian standards for both studied WWTPs. Likewise for other indicators such as electrical conductivity (ranging 4.9-5.4 mS/cm), suspended matter (145-160 g l^-1), chemical oxygen demand (123-160 mg l^-1), biological oxygen demand 5 (172-195 mg l^-1), chloride, Total Kjeldahl nitrogen (TKN) and phosphorus contents (710, 58-66 and 9.47-10.83 mg l^-1 respectively), the registered values do not agree with the set standards established for wastewater treatment. On the other hand, the pH values fitted (oscillating from 6.86 (at G) to 7.24 (at SB) with the Tunisian standards for both WWTPs. After treatment, wastewaters showed better values for the microbiological parameters, especially for the clays designed as AM and HJ1, which eliminated 100% of viruses. In addition, when acid-activated AM clays were applied, a marked improvement in the quality of physicochemical parameters was obtained, especially for suspended matter (2 and 4 g l^-1 for SB and G, respectively), TKN (5.2 (SB) and 6.40 (G) mg/l), phosphorus (1.01 (SB) and 0.81 (G) mg/l). Our results open perspectives for the possibility of efficiently using these specific clays in the enhancement of the quality of treated wastewaters.

Keywords: Clay modification; Microbiological quality; Physicochemical quality; Wastewater; Wastewater clay treatment.

MeSH terms

Clay
Phosphorus
Tunisia
Waste Disposal, Fluid
Wastewater*
Water Pollutants, Chemical* / analysis

Substances

Wastewater
Clay
Water Pollutants, Chemical
Phosphorus