Effect of Optimization of Cultural Parameters on Exobiopolymer Production by Microbial Isolates and Their Application in Wastewater Treatment

Abstract

The optimization of culture media and conditions for efficient production of exopolymers by microorganisms cannot be overemphasized. As such, this work investigated the effect of optimizing culture media on bioflocculant production using Alcaligenes aquatilis AP4 and Bacillus clausii NB2 isolated from wastewater samples. It also studied the application of the resulting bioflocculants for treatment of wastewater. The basal medium used for the batch fermentation was supplemented with different concentrations of carbon and nitrogen sources. The bioflocculants produced were tested on kaolin solution, brewery and palm-oil effluents in concentrations ranging from 100-1000 mg/L. It was observed that optimization of culture media by the two strains had a significant effect (P≤0.05) on bioflocculant production. At 72 hours of incubation, 15.0 and 20.0g/l glucose concentration gave the best conditions for bioflocculant production by isolates AP4 and NB2 respectively. In addition, 0.50 and 0.30 g/l of inorganic nitrogen source ((NH4)2SO4) and 0.70g/L of organic nitrogen (Urea) were required by both isolates. 10 and 15ml/L of bioflocculant dosage respectively gave the best flocculating activities. The ability of the bioflocculants to flocculate kaolin solution, brewery wastewater and palm-oil effluent were confirmed. In addition, the bioflocullants also showed a tremendous ability to reduce COD and turbidity of wastewater.