Production And CharacTeristics of A Bioflocculant Produced By Pseudomonas SP. STRAIN 38A

Screening of microorganisms producing flocculating substances was achieved. A strain secreting a large amount of bioflocculant was isolated from wastewater samples collected from the inlet from Borg El-Arab industrial wastewater treatment plant. Based on the morphological properties and 16S rDNA sequence analysis, the isolate (designated 38A) was classified as pseudomonas sp. exhibiting the highest flocculating activity and a crude polymer yield of 3 g/L after 1 day cultivation. A bioflocculant produced by 38A was heat-stable and had strong flocculating activity in a wide range of pH with relatively low dosage requirement. By studying the flocculating activity of 38A, factors such as bioflocculant dosage, temperature and pH of the reaction solution were tested. The optimal conditions for the flocculating activity were 15 mg/l bioflocculant dosage and pH 7.0, at a temperature of 25˚C. Under these conditions, the flocculating rate of kaolin clay was 99.89%. Different cations were investigated, the best was the CaCl2. Also the optimal concentrations for the flocculating activity was 1ml CaCl2 3%(w/v) which played the synergistic effect on kaolin flocculation. The bioflocculant of 38A was identified as a polysaccharide. Infrared spectra showed the presence of hydroxyl, carboxyl and methoxyl group in its molecules.