Bioflocculant Production by a Consortium of Two Bacterial Species and Its Potential Application in Industrial Wastewater and River Water Treatment

摘要

We assessed the bioflocculant production potentials of a consortium of two marine bacterial species belonging to the Oceanobacillus and Halobacillus genera, isolated from sediment samples of Algoa Bay in the Eastern Cape Province of South Africa. Cell free culture broth of the consortium had a flocculating activity of 98.3%, which is higher than those of pure cultures of the individual species. The purified bioflocculant was more efficient (optimum dose 0.2 mg·ml~(-1)) in the flocculation of kaolin suspension (4 g·l~(-1)) compared to polyelectrolyte (optimum dose 0.3 mg·ml~(-1)) and alum (optimum dose 1 mg·ml~(-1)), which are both commercially available coagulants. A neutral pH condition and the presence of Ca~(2+) as cation resulted in optimum activity of the bioflocculant. Also, the purified bioflocculant removed chemical oxygen demand (COD) in brewery wastewater, dairy wastewater, and river water at efficiencies of 99.7, 99.9, and 63.5%, respectively, and also reduced their turbidity by 93.9, 88.3, and 98.6%, respectively. Composition analysis revealed the bioflocculant to be mainly polysaccharide with an amorphous-crystal-like structure. FTIR spectra revealed the presence of carboxyl, hydroxyl, and amino groups in its thermo-stability test, suggesting a thermostable bioflocculant.