Flocculant Producing Strain And Its Application In Water Treatment

The iron, aluminum flocculants and the polyacrylamide (PAM), the traditional macromolecule flocculants that are used for the water treatment reagents. But they will induce the second pollution. Moreover, the use of the aluminum flocculants and PAM will be the potential threaten to the health of people. Microbial flocculants used in water flocculation and settlements are polymers produced by microorganisms during growing periods. They are new kinds of water-treatment agents extracted or purified from microorganisms or their secretion by means of biological techniques. The safe, high efficient, non-poisonous, harmless, non-secondary polluting microbial flocculants can be naturally decomposed. Since they overcome the shortcomings in utilizing safety and environmental pollution of the inorganic flocculants and organic flocculants, research and exploration of bioflocculants is realistically significant and have wide prospect in application.The results of the experiment on the flocculating characteristic of the bioflocculant produced by strains YZW15 and YZW17 showed that the flocculating activity of the bioflocculant was due to the secondary metabolic products of strains. The bioflocculant was present in the fermentation liquid mainly.Two flocculant-producing strains named YZW15 and YZW17 were isolated from the activated sludge. 16S rRNA sequence showed that both strains were 99.8% similar to Bacillus megaterium IAM 13418. Strains YZW15 and YZW17 showed 94% and 98% of flocculation rate tested by kaolinite precipitation method at pH ranging from 5 to 10.Using the strain YZW17 to treat 30 mL disperse blue wastewater, soil extract, municipal wastewater and highly polluted river water, it was found that each kind of wastewater need different cations as helper ions as far as the best flocculation rate was to be achieved. Removal rates of suspended and colored materials were 79~99% and the removal rate of CODCr was 26~70% by the strain YZW17.The fermentation liquid produced by strain YZW17 must be kept under 4℃, the flocculating activity can keep more than one month.