| Bioflocculant have advantage on easily separated, highly biodegradable, widely range of applications and no environmental pollution. Much research on the screening of bioflocculant producing strain, the optimization of the medium composition, the optimization of the culture conditions, the flocculation activity factors and the treatment on polluted water have been done by experts and scholars.However, selected bioflocculant producing strains always take long fermentation time to product bioflocculant which cost much manpower and material resources in the pre-fermentation. This has disadvantage on large-scale application of bioflocculant. Less research on the application of bioflocculant in the treatment on entrophication water have been done by experts and scholars. The aim of this study is to select an efficient bioflocculant producing strain and research the treatment on entrophication water by bioflocculant.The stain was isolatied from activated sludge wastewater treatment, Chengdu. The flocculation rate for kaolin suspension was determined by spectrophotometry. Take the flocculation rate as standard, an efficient bioflocculant producing stain SNUX-1 has been screed. SNUX-1 was identified as Acinetobacter johnsonii by morphological identification, physiological and biochemical identification and molecular biological identification. The optimization of single factor and orthogonal of nitrogen source, carbon source, initial p H, inoculum size and incubation time have been done, the results showed the optimum condition: carbon source: sucrose 20.00 g/L; nitrogen sources: yeast extract 1.50 g/L; medium initial p H: 8.00; inoculum size: 4.00 %; incubation time: 12.00 h. The optimization of single factor and orthogonal of flocculation system temperature, the type of coagulant, flocculation system p H, broth dosage, coagulant dosage, mixing speed, mixing time and standing time have been done, the results showed the optimum condition: coagulant: Cu Cl2; flocculation system p H : 9.00; broth dosage: 5.00 m L; coagulant dosage: 2.00 m L; stirring speed: 120.00 rpm; stirring time: 7.00 min; standing time: 15.00 min. Under the optimum condition the flocculating rate of the bioflocculant approached 99.10 %. Used ethanol and chloroform-butanol(5:2) to extract the bioflocculant produced by SNUX-1, and took coomassie reaction, biuret reaction, anthrone reaction and full wavelength spectrum scanning to analysis the component of the bioflocculant, the results showed that the bioflocculant produced by SNUX-1showed no color reaction with Coomassie Brilliant Blue and Biuret but showed color reaction with anthrone and combined with the result of full wavelength spectrum scanning we identified bioflocculant produced by SNUX-1did not contain protein and nucleic but contain carbohydrates. Used EDTA, HCl and urea to check the band between biflocculant and kaolin particles, the results showed the bond between bioflocculant and kaolin particles was ionic bond. Combined with the change of the electric potential of flocculation system with the adding of bioflocculant, we speculated the flocculation mechanism of bioflocculant was charge neutralization and bridging. The removal rate of total nitrogen, total phosphorus, chlorophyll a, chlorophyll b, chlorophyll c, turbidity and Humus organics of entrophication water by bioflocculant were 24.77 %, 12.90 %, 0.66 %, 15.80 %, 44.96 %, 76.92 %, 62.37 %.Efficient bioflocculant producing stain SNUX-1can produce much bioflocculant in 12.00 h and the bioflocculant have high flocculant rate on kaolin suspension, which can greatly save manpower and material resource and reducing the cost of production in practice application. The bioflocculant produced by SNUX-1 have ability to remove total nitrogen, total phosphorus, chlorophyll a, chlorophyll b, chlorophyll c, turbidity and Humus organics of entrophication water which makes it possible to use this bioflocculant to deal with entrophication water. |
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