Preparation Of Two Kinds Of Flocculants And Application Research

At present, the flocculant had been widely used in different kinds of wastewater treatment, and had achieved good results. The paper stemed from the major project of national water pollution control and remediation technology, the demonstration topic named Shaying River middle and lower reaches of the agricultural non-point source pollution control and water quality improvement synthesis technology research.Through consulting relevant references, this paper chose four strains which have a wide distribution in the soil, buying from the culture collection. After activation and cultivation of producing flocculant, the bacterial fluid was used to take experiment in kaolin suspension. The following experiments were carried out with Bacillus polymyxa that has a better flocculation effect.The single factor experiment determined the best carbon source for the growth of bacteria was glucose, the best nitrogen source was yeast extract, as well as the best initial pH of the medium was 7.0. At the same time, the result showed that the optimum culture time of strain was 48 hours, the optimum rotation speed was 150 rpm, the optimum culturing temperature was 30 ℃. The flocculation activity of the flocculant could reach to 74%.This article conducts a study aimed at the flocculation system of microbial flocculation. We found out when mixing 15 seconds by medium speed (200 rpm), the flocculation rate could reach the highest 70.2%; when the flocculation deposited the kaolin suspension, Ca2+ showed excellent performance, and the dosage of CaCl2 whose mass fraction was 1% is 5～6 mL, the rate of flocculation reached a maximum of 73.7%; when the dosage of flocculant was 2 mL, the rate of flocculation was up to 74.4%. The introduction of OH could improve the flocculation ability of the flocculant, the rate reached 72.2% when the pH was 8.Meanwhile, the temperature of reaction system had little influence on flocculation rate; then through centrifuging, it was found out that the material in the flocculant was mainly distributed in the fermentation liquid, but not the cell itself. Finally, MBF was applied to try to throw into high concentration organic wastewater for treatment, it found that the effect was not very desirable, and analied the reasons.In the study of PAFC, preparing two kinds PAFC they had different ratios of iron and aluminum (9:1 and 5:5); also we found when the synthesis temperature was 90 ℃, synthesis time was 2 hours, and stirring speed was 200 rpm, the PAFC made out flocculation effect was the best; in the experiment of precipitating kaolin suspension, we found when the dosage of PAFC was about 5 mg, it had the best flocculation effect; for the pH of reaction system, when pH was less than 7, PAFC (5:5) precipitation effect was better; when the pH was greater than 7, PAFC (9:1) precipitation rate was better, it could reach to 65.7%. But under the same processing environment, the precipitation efficiency of PAFC on kaolin suspension was lower than microbial flocculant.Finally, this paper discussed the technical feasibility of flocculant be used in wastewater treatment in the future.