Study On The Preparation And Application Of Poly Aluminum Ferric Silicate

The preparation and application of poly aluminum ferric silicate were studied in this paper. The main content and conclusions are as follows:1. There were many experiments to be performed and be used to establish the optimum preparation process of PAFSC. The following results can be drawn from the experiments: (Al+Fe)/Si=1:1, Al/Fe=3:1, the active pH was 5.3 and the active time was 7 minutes. The coagulant that was prepared under this condition had the optimum performance. During experiments it was noticed that the performance of coagulant was decided by the inter-activity of every factor. And among these factors, the active pH was the most important. The addition of polysilicate in the coagulant made it different from other coagulants and enhanced the performance of coagulant.2. The optimization study of preparation process of PAFSC had been made. There were two ways of optimization that had successfully been carried out: (1) Improving the performance of coagulant by the addition of alkali into coagulant, the enhancement in the effect of coagulation had been made by this way, but the stabilization of the coagulant somewhat decreased. (2) Improving the performance of coagulant was by adjusting the pH of aluminum chloride and ferric chloride solutions with sodium silicate solution. This preparation process was simple and the coagulant was stable. Using this coagulant to treat wastewater, the dosage of coagulant was reduced.3. To test the performance of PAFSC, the river water of HaiHe was used to make coagulating experiment and the experiments of comparison with PAC and PFS had also been made. The result indicated that the effect of PAFSC was better than PAC and PFS. The effect of PFS was the worst. In addition, the influence of pH on the effect of PAFSC was comparatively the least.4. The waste water of paper mill was treated by PAFSC and the comparison with PAC and PFS was also made. When the dosage of coagulant was same, the removal of chroma by PAFSC came up to 94.16%, and the removals of chroma by PAC and PFS were 88.54%and 73.20%, respectively. For the black liquor of paper mill, the removal of COD by PAFSC came up to 73.77%, the removal of COD by PAC was 63.75% and PFS had no apparent effect on the removal of COD in the black liquor. PAFSC could decrease the turbidity of the waste water of deinking mill from 274.35 NTU to 6.74 NTU, and PAC could decrease the turbidity from 274.35 NTU to 9.02 NTU. In addition, compared to PAC and PFS,the floccule formed by PAFSC during the water treatment was larger and denser, the speed of sedimentation was quicker.