LAUSR

Abstract Bioflocculant is an extracellular biopolymer substance secreted naturally by microorganisms during their growth. It has piqued the interest of many researchers due to its biodegradability, nontoxic properties, and potential as a substitute for conventional flocculant where its usage may lead to environmental and health issues. In the present study, Aspergillus niger DWB was used to investigate the production and characterization of bioflocculant. The bioflocculant was produced by utilizing agricultural residue from the oil palm industry, oil palm empty fruit bunch (OPEFB) fiber as the carbon source. The effect of pH of the medium, as well as the inoculum size on the bioflocculant production, was examined. The maximum bioflocculant yield obtained after 48 h of fermentation was 9.48%/g substrate under tested condition. In addition, the bioflocculant produced showed a good flocculating rate in kaolin suspension at pH 6, within 15 min of retention time and using 4 ml of bioflocculant dosage. The functional group of the extracted bioflocculant was determined using Fourier-transform infrared (FTIR) spectroscopy, which revealed the presence of hydroxyl and carboxyl groups. These functional groups attributed to their flocculating abilities. The results obtained from this study suggested that the agricultural waste, OPEFB fiber can serve as a suitable solid substrate in the production of bioflocculant.