Using Biological And Chemical Combination Technology Of Poly Silicon Ferric Sulfate Coagulant

In order to solve the problems of domestic and overseas methods of preparation of PFSS, in this thesis a new method is developed in which industrial FeSO₄ is used as material, Fe₂(SO₄)₃ is prepared by the oxidation action of Thiobacillus ferrooxidans, then PFSS is prepared by mixing polymeric silicic acid and Fe₂(SO₄)₃. The flocculating agent prepared by this method is used to treat stimulant waste water, the effect is favorable and the applied foreground is comparatively wide.Thiobacillus ferrooxidans is naturally filtrated from extremely acid condition, the influence of pH, tempereture, amount of inoculation on lag phase of Thiobacillus ferrooxidans axe studied, the results show that the lag phase can be reduced under pH2.0, temperature30℃ and increasing amount of inoculation. The bacteria which can resist pH1.7 are selected through natural domestication. The time of complete oxidation of Fe²⁺ is brought forward about 12h after ultraviolet mutagenesis, and the average of the oxidation of Fe²⁺ is increased from 0. 188g/L·h to 0. 206g/L·h , the activity of the bacteria is improved obviously.The growth kinetics of the bacteria that have been domesticated is studied. Based on Monod equation, the growth kinetics modelμ=(0.14×[Fe²⁺])/(0.94+[Fe²⁺] + 2.97×[Fe³⁺]) is established when the substance inhibitionand product inhibition are taken into account. the forecasted values of equation favorably inosculate to the values of experiment.In batch suspended culture, the industrial FeSO₄ is used basic matieral, after four times culture the rate of oxidation is steady. the optimized experimental conditions are as follows: H₂SO₄:FeSO₄ ? 7H₂O(ratio of mol)is 1: 8, aeration amount is 60L/h, the lag phase is reduced by increasing the ratio of primary liquid and feed liquid. With the increasing of original concentration of Fe²⁺ , lag phase will be prolonged, and the average rate of oxidation will be reduced.The oxidation rate is increased by immobilized cell technology to increasing cell concentration. In the experiment,the polypropylene fibre is used as immobilization carrier, the bacteria are absorbed onto the carrier by method of adsorption. The influence of pH on immobilization process is investgated, the result shows that pH1.8 is comparatively favorable to immobilization. When the rate of oxidation is steady, the rate of oxidation (0. 42gFe²⁺/L ? h) of immobilized cells is obviously quicker than the rate (0. 2 gFe²⁺/L ? h) of suspended cells, under room temperature condition, aeration amount 100L/h is optimal. During the reaction process, the value of pH hoists at first and then descends, the original pH1.8 can reach the highest 2. 5, and then descends to 1.8. During the reaction, the loss of total iron ion is very little, which is propitious to the long-term operation of the reactor.