The Research On Flocculating Activity And The Kinetic Behavior Of Fermentation Of Flocculant-producing Bacterial Strain GA1

Bioflocculants, having good flocculating activity, are the metabolic products of the microorganism, which are safe, non-toxic, easily cultivated, and can be biodegraded. Its main components are amylases, glycoprotein, nucleic acid, proteinicsubstance. Since the advantages of using bioflocculants in both environmental safety and economic over some other inorganic flocculants and organic flocculants, great attention has been paid to explore the bioflocculants mechanism and to investigate their characteristicsinuse. As a result, it is of great value in the research of bioflocculant.At present ,the high production cost is main obstacles of the bioflocculant into the market , therefore optimizing culture medium, enhancing the biological flocculantout yield, lowering the production cost is the key of it carring on industrialization production.Paenibacilluspolymyxa GA1 was a bacterium with high bioflocculant producing rate which was screened out from soil by our lab. It could produce bioflocculant MBFGA1 with super ordinary flocculability and decolorizing property. This study focused on flocculability of MBFGA1 and the situation of GA1's growth. The works remained: (1) Investigate the effects of the initial substrate concentration on the growth and outputs of flocculant of a laboratory screening flocculant-producing bacteria GA1 by using the monad equation. (2) The Maximum specific growth rates of GA1 to carbon and nitrogen (3) A preliminary study on kinetic behavior of the fermentation of GA1.The effects of the initial substrate concentration on the growth and outputs of flocculant of a laboratory screening flocculant-producing bacterial strain GA1 were investigated by using the kinetics equation.The maximum specific growth rate of strain GA1 to carbon and nitrogen were 0.099h-1and 0.095h-1, respectively. The semi-saturation constants of strain GA1 to carbon (KS.C) and nitrogen (KS.N) were 1.503 and 0.315, respectively. The result of KS.C higher than KS.N showed that, the compatibility of nitrogen to GA1 is further more than that of carbon.When the concentrations of carbon and nitrogen from ranges of 1 g/L to 48g/L and 0.1g/L to 4 g/L, respectively,the carbon or nitrogen as the single restrictive substrate, the specific growth rate and the maximum growth of strain GA1 increased rapidly. At carbon/nitrogen of 10 and sucrose concentration of 40 g/L, flocculant yield reachs 0.306 g/g sucrose. The theory cell yield coefficient Y *x/s is 0.381 g/g ,the maintenance coefficient of cell growth is 0.0311 g/g·h , indicates flocculant-producing bacterial strain GA1 with the potential for industrial production.Using base on the bioflocculant (MBFGA1) , the pretreatment of dairy processing wastewater was studied. The Results showed that the optimum dosages was 15 mg/L and hydrodynamic conditions was 150r/min stirring for 30 seconds, and then 30 r/ min stirring for 20 minutes, When the pH value was 4.0, the flocculation effect of MBFGA1 was best. Temperature appears to had an important effect on the removal efficiency of turbidity and COD in dairy processing wastewater. turbidity removal efficiency always maintained at more than 85%, COD removal efficiency achieve the maximum 65.0% at 30℃.