Modeling as a New Tool to Predict Slow sand Filtration Efficiency to Remove Pb from Contaminated Water: Water Velocity Effect

Document Type : Original Research Paper

Authors

1 Cadi Ayyad University, Faculty of Sciences and Techniques of Gueliz, Marrakech, Morocco

2 Regional Laboratory for Epidemiological Diagnosis and Environmental Hygiene, Boulevard des Hôpitaux, Gueliz-Marrakesh, Morocco

3 Higher Institute of Nursing Professions and Health Technology, ISPITS – Marrakech, Morocco

4 UFR de Sciences Pharmaceutiques et Biologiques, Centre de Dosage des Eléments Minéraux, (CDEM), 9 rue Bias, BP 53508, 44035 Nantes, France

10.22059/poll.2025.391518.2826

Abstract

To address water scarcity in the Marrakech region of Morocco, the agricultural reuse of wastewater emerges as a promising solution. Slow sand filtration has gained prominence in wastewater treatment, presenting an effective approach. This study explores the potential of slow sand filtration in removing Pb from contaminated water, specifically from the Tensift River, which receives wastewater directly from the industrial unit of Zn and Pb extraction at the Draa Lasfar mine situated 13 km northwest of Marrakech City. Physicochemical analysis revealed Pb concentrations of 133 ± 16 µg/L upstream and 317 ± 27 µg/L downstream of the mine discharge point. This study incorporates a continuous fixed-bed adsorption study, utilizing sand as an adsorbent for Pb. The impact of three water velocites (0.5, 1, and 2.5 cm/min) on the removal process is investigated, revealing that breakthrough curves are influenced by water velocity. Results showed that the lowest velocity (0.5 cm/min) achieved the best Pb removal, with delayed breakthrough and improved adsorption efficiency. The saturation of the adsorption sites was reached more rapidly at higher velocities (2.5 cm/min). This phenomenon is attributed to slower transport at low velocities, allowing sufficient time for Pb to bond with sand sites. A logistic model was applied to describe the adsorption kinetics, demonstrating good agreement between predicted and experimental breakthrough curves. This model incorporated water velocity (Vi), Pb concentration [Pb](t), and a system-specific constant K, offering a predictive tool for optimizing filtration performance in real conditions.

Keywords

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References

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Pollution
Volume 11, Issue 4
October 2025
Pages 1363-1370

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