Resumo

KHELLADI, Racha M Bouchenak et al. Enhanced coagulation-flocculation of domestic wastewater using sustainable plant-based material: a comparative study of nopal, agave, and eucalyptus. Water SA [online]. 2026, vol.52, n.2, pp.151-160. ISSN 1816-7950.  https://doi.org/10.17159/wsa/2026.v52.i2.4247.

This study addresses the critical challenge of sustainable wastewater treatment by investigating and valorizing agro-industrial residues as high-performance, zero-waste coagulants. The scope of this engineering investigation was the optimization and comparative assessment of 4 readily available materials - bentonite (BN), eucalyptus leaf powder (ELP), agave powder (AP), and the novel nopal fibrous residue powder (NFRP) - as alternatives to aluminium sulphate (AS) for urban wastewater treatment. The core novelty and innovation lie in the successful utilization of the discarded fibrous residue of the nopal cactus; this approach fundamentally shifts the paradigm from complex, resource-intensive extraction of nopal mucilage to the direct, simple use of a high-volume waste product. This leverages the lignin- and tannin-rich components, which are shown to be responsible for bio-flocculation, making the process intrinsically simpler, cheaper, and scalable, relative to state-of-the-art mucilage-based technologies. The statistical analysis confirmed significant differences in pollutant removal based on the material (p < 0.01). Agave powder (AP) was statistically superior for clarity, achieving a maximum turbidity removal percentage (TRP) of 97.76 ± 2.180% at an optimal dose of 20 mg/L, statistically outperforming AS. Conversely, for the removal of organic pollutants, the chemical standard AS was superior in single-dose trials, with COD reduction (CODR) ≈ 88.5%. However, the synergistic combination of NFRP (100 mg/L) and BN (60 mg/L) achieved the highest CODR ≈ 92.13 ± 0.398%, successfully exceeding the performance of AS. Furthermore, AP demonstrated high effectiveness in ammoniacal nitrogen removal (≈ 75%), highlighting its multi-pollutant capacity.

Palavras-chave : agave; bio-coagulant; eucalyptus; nopal residue; turbidity removal.

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