| An excellent strain (designated as T-3) which produces bio-flocculants was isolated from soil samples, and identified as Klebsiella sp. species based on the analysis of morphology，physiology and biochemistry and 16S rDNA sequences measurement. The effects of culture conditions such as pH values, temperature, carbon sources and nitrogen sources on bio-flocculants production by T-3 strain were studied. The experiment results show that T-3 strain has better adaptability to carbon sources and nitrogen sources, and higher capacity of bio-flocculants was obtained when the initial pH value of culture and temperature were 9 and 25℃ respectively. Based on the colorimetric reactions of proteins and polysaccharide substance, ultraviolet scanning analysis and Fourier Transform Infrared Spectroscopy analysis, it is found that the bio-flocculants produced by T-3 strain contains —OH and —COO- groups and belongs to anionic type flocculant. Moreover, the main component is polysaccharides. The treatment of oily cold-rolling wastewater by the bio-flocculant was investigated and the better result was obtained. When the dosages of CaCl2, bio-flocculants and poly aluminium chloride were 4 g·L-1, 10%(volume fraction) and 1 g·L-1 respectively, and the pH value was 7.0, the oil concentration, COD and turbidity were decreased to 10 mg·L-1, 218.4 mg·L-1 and 1.36 from 4819 mg·L-1, 28456.8 mg·L-1 and 3950 with the removal efficiencies of 99.79%, 92.32% and 99.97% respectively. The interaction between flocculant and oily droplets is achieved by the interaction of Van der Waals force, hydrogen bond and the bridged coordination of Ca2+，in which the bridged coordination of Ca2+ is the dominant. |
