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<p>The Esparto paper industry (EPI) in Kasserine, Tunisia, operated by the National Company of Cellulose and Esparto (SNCPA), generates large volumes of highly alkaline and polluting wastewater. Effective treatment is required prior to discharge to prevent environmental harm. This study investigates the coagulation–flocculation process for treating Esparto Paper Industry Wastewater (EPIW) using three common coagulants: aluminum sulfate (Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>), ferrous sulfate (FeSO<sub>4</sub>), and ferric chloride (FeCl<sub>3</sub>). Raw wastewater exhibited extreme pollution characteristics (pH 12.5 ± 0.2; COD 8600 ± 200&#xa0;mg/L; turbidity 2400 ± 50 NTU; salinity 2600 ± 50&#xa0;mg/L). Jar tests were conducted under identical conditions without pH adjustment, simulating natural discharge scenarios and minimizing treatment costs. Results demonstrated that aluminum sulfate,&#xa0;when combined with an anionic polyelectrolyte at 0.1 g/L, was the most effective coagulant under these extreme alkaline conditions, achieving remarkable removal efficiencies of approximately 90% for COD and 83% for color at an optimum dose of 1.5&#xa0;g/L, producing a treated effluent with pH of 7.5, residual turbidity of 310 NTU, and salinity of 3800&#xa0;mg/L. Ferrous sulfate achieved 81% COD and 72% color removal at 4.5&#xa0;g/L, while ferric chloride removed 73% COD and 60% color at 4.0&#xa0;g/L. These findings demonstrate that direct coagulation at native pH, in combination with a small dose of anionic polyelectrolyte, is a technically viable and economically advantageous pre-treatment strategy for highly alkaline industrial wastewaters, offering substantial reductions in chemical consumption, operational complexity, and overall treatment costs, with significant implications for sustainable industrial wastewater management.</p> Graphical Abstract <p></p>

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Effective Treatment of Highly Alkaline Paper Industry Wastewater by Coagulation-Flocculation Process Without pH Adjustment

  • 期刊论文

  • 发表日期：

    2025年12月12日

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  • Boubaker FEZZANI

摘要

The Esparto paper industry (EPI) in Kasserine, Tunisia, operated by the National Company of Cellulose and Esparto (SNCPA), generates large volumes of highly alkaline and polluting wastewater. Effective treatment is required prior to discharge to prevent environmental harm. This study investigates the coagulation–flocculation process for treating Esparto Paper Industry Wastewater (EPIW) using three common coagulants: aluminum sulfate (Al2(SO4)3), ferrous sulfate (FeSO4), and ferric chloride (FeCl3). Raw wastewater exhibited extreme pollution characteristics (pH 12.5 ± 0.2; COD 8600 ± 200 mg/L; turbidity 2400 ± 50 NTU; salinity 2600 ± 50 mg/L). Jar tests were conducted under identical conditions without pH adjustment, simulating natural discharge scenarios and minimizing treatment costs. Results demonstrated that aluminum sulfate, when combined with an anionic polyelectrolyte at 0.1 g/L, was the most effective coagulant under these extreme alkaline conditions, achieving remarkable removal efficiencies of approximately 90% for COD and 83% for color at an optimum dose of 1.5 g/L, producing a treated effluent with pH of 7.5, residual turbidity of 310 NTU, and salinity of 3800 mg/L. Ferrous sulfate achieved 81% COD and 72% color removal at 4.5 g/L, while ferric chloride removed 73% COD and 60% color at 4.0 g/L. These findings demonstrate that direct coagulation at native pH, in combination with a small dose of anionic polyelectrolyte, is a technically viable and economically advantageous pre-treatment strategy for highly alkaline industrial wastewaters, offering substantial reductions in chemical consumption, operational complexity, and overall treatment costs, with significant implications for sustainable industrial wastewater management.

Graphical Abstract