The Research Of Microbial Flocculant's Application In Industrial Wastewater Treatment

For a long time, the flocculants used in water and wastewater treatment mainly include iron salt, aluminum salt and polyacrylamide flocculant. The related research suggests that taking superfluous aluminum ion from drinking water would increase the proportion of suffering from senile dementia. The iron salt would corrode the metal and color the water. High concentration of iron would lead to negative impact on human and the zoology. Synthetic high-polymer flocculant has a little toxicity. For example, the monomer of the polyacrylamide has nerval toxicity and lead to macrocephaly, cancer and mutation, thus limit their application.The results of the enrichment culture and screening of the microorganisms that can produce bioflocculant is: 33 bacterial strains were Separated according to the characteristics of the bacterial communities. After screening, 13 bacterial strains were gained. Their flocculating activities are all over 75%.The studies of the best culture condition of the microorganisms(BF3-3) which produce the bioflocculant suggest that the best culture condition of BF3-3 is initiative pH is 7.5, culture time is 24h, culture temperature is 30癈,rotation speed 170r/min, the dosage of the culture (in 250ml flake) is 100ml. The gradients of BF3-3's culture medium is: sucrose 40g. sodium nitrate 0.5g, yeast extract 2g, MgSO4 . 7H2O 0.25g, KH2PO4 0.5g, initial pH 7.5.The flocculating effect of microbial flocculant on Kaolin suspension and diopside-processing wastewater reached the taditional flocculants. Thus, it maybe used to flocculating Kaolin suspension and diopside-processing wastewater as the new generation flocculant.The study of MBF3-3 flocculating beer wastewater suggests that the flocculating effects of MBF3-3 become obvious when beer wastewater's pH>9. Altering the sequence of changing the wastewater's pH and adding MBF3-3 has obvious effect on the flocculating effects. The flocculating effects of HPAM MBF3-3 + FeCl3 become better when the pH of the beer wastewater elevated. MBF3-3+AlCl3and PAC's flocculating effects have little difference and thy all getting the best flocculating effects at pH:10.Their turbidity removal ratio respectively getting to 58% and 59.6%. According to the CODcr removal ratio, MBF3-3 is the best, HPAM the second, PAC the worst. According to the dosage, MBF3-3 is the least, HPAM the second. PAC the most. In general, MBF3-3 showed the best flocculating effects to beer wastewater.The study of MBF3-3 flocculating petrochemical wastewater suggests that The flocculating effects of MBF3-3 become better when the pH of petrochemical wastewater elevated. So do MBF3-3+PAC, but effects are a little better. The flocculating effects of PAC are stable while change the pH. HPAM has good flocculating effects only in pH: 10-11. Compared with PAC, the turbidity removal ratio of MBF3-3 amounted to 90.1% and its dosage is 0.9ml, far below the PAC's dosage 3.5ml.