Studied On The Influence Factors And The Flocculating Capability Of Bioflocculant Produced By Paenibacillus Polymyxa GA1

A bacterial strain, numbered GA1, which can produce bioflocculant with high flocculating activity was screened from soil by means of the common bacteria screening and purification method and was identified according to its morphological, physiological and biochemical characters, as well as 16S rDNA sequence homology comparison, and DQ166375 is its GenBank accession and its name is Paenibacillus polymyxa GA1 CCTCC M 206017.Results of thermal stability experiment were showed that, after different high temperatures treatment of fermentation broth their flocculation rates were also remained in about 99%.It could be concluded that all of those bioflocculants that produced by bacterial strain GA1 had a good thermal stability. The main component of MBFGA1 was polysaccharide but not reductive polysaccharides, which was determined by Anthrone reaction and Fehling reaction .The experiment of ultraviolet spectrum analysis was used to test absorption peaks of MBFGA1 at the wavelength range of 200~400 nm; there were no absorption peaks at 280nm, 260~290nm which represent protein and purine and pyrimidinde ring in nucleic acid, respectively. In addition, the Infrared spectrogram of MBFGA1 was a typical polysaccharide spectrogram and there were characteristics absorption peaks on it .MBFGA1 was used to investigate its flocculating capability in the following waster water, the liquid of kaolin, soil suspended liquid, coal-washing wastewater and the landfill leachate with orthogonal experiments, the inspection of granularity and the scanning electron microanalysis; meanwhile the Anthrone reaction and Infrared spectrum are also applied to identify its main component. Each flocculating influence factors played different roles during the process of flocculating. pH was the main factor in the flocculating of liquid of kaolin and landfill leachate and soil suspended liquid and coal-washing wastewater were all mainly controlled by dosage quantity of fermentation broth. In the optimal flocculating conditions obtained from the orthogonal experiments, the flocculating rates of the liquid of kaolin, soil suspended liquid, coal-washing wastewater and the landfill leachate were 99.53%, 99.50%, 98.2% and 75.60%, respectively. There was a correlation between pH and charge of wastewater particles surface. The higher of initial pH wastewater the bigger value of appearance and optimum flocculating was needed. MBFGA1 could flocculate effectively in alkaline condition. In addition, the distribution of granularity has changed after flocculated. The size of the average granularity of soil became bigger after flocculation, and reached over 10μm, but for the other three kinds of granularity just the opposite phenomenon has occurred, and their sizes were all less than 10μm. From the photos of scan electron microanalysis of four types of granules, it could be drawn that there were no obvious differences in the appearance. From the above results, it could be presumed that MBFGA1 can be the best flocculate for the granule -highly-concentrated waste water and the dominative flocculating mechanism of the flocculant was mechanism of adsorption-bridge.There were 9 tested samples which could be extracted by acetone in 16 samples of different carbon and nitrogen sources . And those samples were high temperature and high pressure resisted material from the results of thermal stability .Experiments of ultraviolet spectrum analysis were used to test absorption peaks of those 9 samples and meanwhile it showed that they were not protein or nucleic acid .Especially, the 4 samples with sucrose as their fermentation broth of carbon source could be extracted microbial polymer. The 4 samples predominated in the aspect of production and solubility, and the highest production sample was 8.418 g/L which was with sucrose and yeast extract as fermentation broth among them. Sample NO.1,NO.2 and NO.3 were those in above of 4 samples and there were typical Infrared spectrograms of polysaccharide and the three spectrograms outline appeared almost the same shape and absorption peaks. On the other hand, those samples which with peptone as nitrogen in their fermentation broth were different each other in their Infrared spectrograms.