Preparation Of Poly-silicon Sulfate Flocculants Using Wastewater And Fractal Simulation Of Floe Growth

Three kinds of inorganic flocculants called poly-silicon ferric sulfate (PFSS), poly-silicon aluminum sulfate (PASS), and poly-silicon ferro-aluminum sulfate (PAFS) were made from bentonite, Al3+contented wastewater, Fe3+contented wastewater and98%sulfuric acid at normal temperature, respectively. And they were applied to treat banknote printing wastewater. The experiment results revealed that coagulation effect of PFSS was not good, there were few tense floes, the residual chemical oxygen demand (COD) of effluent of which color was quite dark was rather high; coagulation effects of PASS and PAFS were pretty good, there were lots of loose floes, the residual COD of effluent of which color was rather light was fairly small.The impacts of dosage on coagulation effect of rare-earth flocculants made from rare-earth salt and rare-earth ore were discussed, respectively. The impacts of blending ratio on coagulation effect of PAFSRE made from rare-earth ore and PAFS were also discussed. The results showed that coagulation effect of rare-earth flocculants was pretty good, and coagulation effect was not obviously influenced by the blending ratio, namely, there was not evident synergy effect between PAFS and rare-earth fiocculants.Based on the platform of MATLAB, two-dimensional and three-dimensional floc growth were simulated using improved DLA model, respectively. Parameters such as fractal dimensions and porosity were calculated for the sake of discussing the impacts of Ns, Ms and Pr on the results of fractal simulation of floc growth. The results showed that the smaller the Ns, the bigger of moving region, the more branches of flocs, characterized with the decrease of fractal dimension and the increase of porosity; the smaller the Ms, the floes had a more obvious growing tendency towards discrete clusters, characterized with the decrease of fractal dimension and the increase of porosity; the smaller of reaction probability, the denser of flocs, characterized with the increase of fractal dimension and the decrease of porosity; The flocs would obviously grow towards the direction whose reaction probability was bigger, however, the fractal dimensions of the flocs that grew towards different directions were more or less, which were of the same fractal nature. The impacts of Ms and Pr on the results of fractal simulation of three-dimensional floc growth using DLA model were also rather obvious. A discrete clusters would be formed as Ms was getting smaller, contributing to the reduction of the cyclotron radius Rc, of which fractal characteristic became increasingly inconspicuous. The smaller of reaction probability, the larger of moving space of particles, resulted in the denser of flocs, characterized with the gradual reduction of cyclotron radius Re.