Chitosan Beads as Eco-Friendly Bioflocculants for Oily Wastewater Treatment: Effect of Bead Diameter and Dosage on Flocculation Performance

This study investigates the use of chitosan derived from shrimp shells as an eco-friendly bioflocculant for the treatment of oily wastewater generated by the petroleum industry. In this work, chitosan was not only synthesized but also processed into spherical beads, and the influence of bead form, diameter, and mass on flocculation performance were examined, representing the main novelty of the study. The oily wastewater used was collected from a southern Algerian oil facility. Chitosan was extracted through sequential demineralization, deproteinization, and deacetylation and subsequently characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), confirming successful deacetylation, a semi-crystalline structure, and a heterogeneous surface morphology favorable for pollutant interaction. Coagulation–flocculation experiments were carried out to evaluate the effects of key operational parameters, including pH, flocculant dosage, contact time, and bead characteristics. Optimal treatment conditions were obtained at pH 6.4 and a dosage of 50 ppm, achieving a maximum turbidity removal efficiency of 63.09%. The results further showed that smaller bead diameters and lower bead mass improved treatment efficiency, while excessive bead mass led to reduced performance due to overdosing and particle restabilization. Overall, chitosan beads show potential as a sustainable and biodegradable alternative to conventional flocculants for oily wastewater treatment.