The Research Of Chemical Modification Of Compound Bioflocculant

Of all the water treatment technologies in industrial wastewater,downstream industries, food production and fermentation , flocculation (coagulation) is the most economy and convenient method. Now, studies on efficient and nontoxic flocculant become more and more important in environmental science and engineering. Today, research trends of flocculation process are from focusing on optimization of inorganic, organic flocculants process to Bio-flocculant compound, complex and chemical modification. In this paper, chemical modification of compounded Bio-flocculant were studied to increase its stability and its application scope in sewage treatment.The activity of Bio-flocculant is good , but it largely depend on coagulant metal ions Ca2+. In the experiment of kaolin slurry as a waste of flocculation, compound bio-flocculant without coagulant metal ions Ca2+, the transmission percent is 7.84% after its flocculation, but the transmission percent is 96.4% after adding coagulant metal ions Ca2+, The latter one is 12 times as the former one. In order to reach better flocculation effect under the condition of without introducing metal ion , Bio-flocculant compound, acrylamide, starch compound were taken to carry out chemical modification, to increase its molecular weight, enhance flocculation effect, as well as the natural degradation.The optimal conditions of modification of complex CBF were as followed: the concentration of initiator cerium ammonium nitrate is1.5×10-3 mol/L , the reaction temperature is 50℃, reaction time is 2.5h~3h, pH =8, the ratio of the CBF, starch, acrylamide is 1:1:4.The results showed that modified CBF has some thermal stability, but the flocculation effect dropped 13.2% because of the protein denturation. Zeta potential experiment showed that the value if it is in the range of -4~-9mV under the condition of pH = 3~10, it could be concluded simulated wastewater of kaolin slurry can de easily to precipitate. AFM results showed that the particles of CBF modification of kaolin slurry is larger than non-modified particles. Finally, the process of flocculation and its mechanism were preliminary studied.