| Microbial flocculants are polymers with flocculating activity produced by microorganisms during their growth. Their chemical components are polysaccharide, protein, glycoprotein and nucleic acid. Comparing with other flocculants, microbial flocculants are safe, high-efficiency and readily biodegradeable. With the enhancement of people's environmental consciousness, the studies of microbial flocculants have drawn more and more attentions. The paper concentrates on the screening and identification of bioflocculant-producing bacterias, the identification and components analysis of the product, and the optimization of culture medium and cultivation conditions. The main results are as follows:From the active sludge microbial flocculant producing strain X-1 was isolated and purified. The morphology, physiological and biochemical properties of bacteria and 16SrDNA gene sequence demonstrated that X-1 was closely related to the genus Ochrobactrum,sp. which has not been reported among flocculant-production strains. The main metabolites of strain X-1 was preliminary qualitative for much saccharide compounds through the protein, carbohydrate qualitative analysis.Through single factor the conditions of fermentation which benefit the strain to produce flocculant were optimizied. The optimum culture conditions were as follows: 15g/Lglucose,0.2g/L(NH4)2SO4,0.5g/Lyeast,2g/LK2HPO4.3H2O,5g/LKH2PO4.3H2O,0.0 4g/LMgSO4, 0.1g/LNaCL, initial pH 7.5-8.0, temperature 30℃, inoculation amount 3%(V/V), rotation speed of rocking bed 180r/min, volume in shake flask 30mL/250mL and culture time 72h. Under the optimum condition, flocculating efficiency achieved 89%, enhanced by 25% than the value to the initial.With kaolin clay suspension as test sample, the flocculating characteristics of strain X-1 production was studied. When pH is 8 to 10, flocculant dosage is 2%(volume fraction), coagulant aid CaCL2 dosage is 0.1 g/L, the microbial flocculant has an optimal flocculation of Kaolin clay suspension. |
PDF Full Text Request