Cocoyam powder extracted from Colocasia antiquorum as a novel plant-based bioflocculant for industrial wastewater treatment: Flocculation performance and mechanism

In the current investigation, the comparative study of cocoyam bioflocculant (CYBF) and chem-ical flocculant for the removal of heavy metals, COD, BOD, TDS, TSS, sulphate and nitrate from tannery effluent, and dyes from synthetic dye wastewater were examined. Different analytical techniques, including Fourier transforms infrared (FTIR), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX), were used to characterise the extracted bioflocculant. FTIR spectral measurement of the bioflocculant demonstrated the presence of hydroxyl, carboxyl, and amino groups. By using bioflocculant, the highest removal of TSS (85.5%), TDS (76.2%), BOD (74%), COD (50.5%), sulphate (54.4%), nitrate (52%), Lead (65%), Chromium (60%), Nickel (57.9%), from tannery effluent was achieved at pH 6 and bioflocculant dosage of 8 mg/L. While, 80% congo red, 79% methyl orange, 73% safranin, and 72% methylene blue were removed from synthetic dye wastewater by cocoyam bioflocculant. Two flocculation mechanisms were found for dye removal, electrostatic force of attraction, and hydrogen bonding. In the case of metal adsorption, only electrostatic interactions were observed between metal ions and functional groups of bioflocculant. The cocoyam bio-flocculant exhibited excellent flocculation efficacy and thus can be used in wastewater treatment to remove heavy metals and other pollutants.

Automated summary

In this study, the effectiveness of cocoyam bioflocculant (CYBF) and chemical flocculant in removing heavy metals, COD, BOD, TDS, TSS, sulphate, nitrate, and dyes from tannery effluent and synthetic dye wastewater was compared. Various analytical techniques were used to characterize the bioflocculant. The results showed that the CYBF had excellent flocculation efficacy, achieving high removal rates for various pollutants. It was found that electrostatic force of attraction and hydrogen bonding were the main mechanisms for dye removal, while only electrostatic interactions were observed for metal adsorption.