The Effect of Bioflocculants and Cationic Inducers Concentration on Harvesting Chlorella vulgaris Biomass Using Fungal Aspergillus niger Bioflocculation Method

Abstract

Energy consumption from non-renewable fuels is increasing, so there is a need for a new energy source from microalgae. The microalgae Chlorella vulgaris has a high lipid content ranging from 2-77% of the dry weight of the biomass, but it small size, ranging from 2-10 micrometers, which makes it uneconomical at the harvesting stage. One of the cheaper, effective, and environmentally-friendly harvesting methods is bioflocculation. The bioflocculation was carried out using the help of fungi by activating Extracellular Polymeric Substances (EPS) on positively charged fungi which would stick to negatively charged microalgae so that the charge became neutral and formed flocs. Previous research on the efficiency of harvesting bioflocculation of Chlorella vulgaris using Aspergillus niger pellets still takes a long time. Harvesting of Chlorella vulgaris with Aspergillus niger pellets was able to increase the efficiency of bioflocculation with the optimal parameters which were at pH 8, cationic inducer of 60 mM, bioflocculant dose of 3.5% w/v, and stirring speed of 150 rpm by 93% with a biomass of 333 mg within 48 hours. The bioflocculation harvesting method with fungi pellets can reduce time, save energy, increase harvesting efficiency, and not produce side products so harmful to the environment.