| This paper studied the preparation of poly-silicic-ferric-zinc(PSFZ) coagulant from industrial wastes(fly ash and hot-galvanized steel pipe dregs), optimized the influencing factors of domestic sewage treatment by PSFZ, and established the application software titled Coaulgation Control Paramenter Prediction System Based On Fractal Theory. The research mainly conducts the following aspects.(1) The preparation of PSFZ includes the pretreatment of raw materials, the polymerization of PSFZ, and the characterization of coagulant. The Box-Behnken design(BBD) was employed to optimize the condictions in extracting silicon oxide from fly ash and the optimum preparation conditions were heating temperature, heating time, liauid-solid ratio, and NaOH concentration of 100 ?, 65 min, 2.97 ml/g, and 10.5 mol/, respectively. Based on the orthogonal experiment, the optimum conditions for the polymerization of PSFZ was obtained where(Fe+Zn)/Si moral ration was 4:1, polymerization pH value was 1.5, and polymerization temperature and time were 60 ? and 90 min, respectively. In addition, variance analysis suggested that(Fe+Zn)/Si moral ration, pH value, polymerization time had an important influence on the experiment results at confidence level of 0.05. The surface morphology, crystal characteristics, and structure were inspected by Scanning Electron Microscopy(SEM), X-ray Diffraction(XRD), and Infrared Spectroscopy(FT-IR), respectively. The results indicate that PSFZ which is composed of many crystals and amorphous metal complex polymer present network space structure with large surface area, thus leading to its stronger enmeshment, absorption, and bridge capability.(2) The research of domestic sewage treatment by PSFZ contains three facts: the optimization of experimental factors on domestic wastewater treatment by PSFZ, the comparison of coagulation effect by PSFZ and PAC, and the selection of coagulation dynamics. The optimal factor levels in domestic sewage treatment by PSFZ were found to be n(Fe+Zn)/nSi of 4.41, polymerization pH value of 1.39, and coagulation dosage of 0.92 mmol/L using BBD, corresponding to residual turbidity, COD and TP removal of 3.13, 78.60%, and 96.84%, respectively. PSFZ and PAC were employed to treat domestic wastewater and the results indicated that PSFZ has better coagulation performance than PAC with various coagulant dosage and initial pH value. The coagulation dynamics of PSFZ was probed by orthogonal experiment. The results showed that all the coagulation factors could not achieve optimizations in the same technology condition and different hydraulic conditions should be provided according to different physical demand. Furthermore, agitation step made a significant impact on the three water quality indexes using variance analysis. It suggested that appropriate agitation step of G value could form bigger flocs and increase the settling rate with orthokinetic/perikinetic flocculation and differential sedimentation while the formed flocs were not be broken mechanically, so the efficiency of coagulation would be enhanced.(3) The study on the application of fractal simulation is divided into several parts, such as the establishment of mathematical model between fractal model variables and relevant water quality parameters, the confirmation of mathematical model between fractal dimension and coagulation parameters, the interface design of application software, and so on. With similar graphical shapes and fractal dimension(error within ±7%), the numerical relationship between sewage turbidity and initial population of particles, wastewater temperature and step, and raw water p H value and release radius were sought out, then the mathematical models between fractal model variables and relevant water quality parameters were determined using polynomial fitting in wastewater treatment by PSFZ. When PSFZ dosage and whole GT value were selected as experimental factors and fractal dimension was choosen as response value, a quadratic equation whose correlation R2 is 0.9274 between experiment factors and response was investigated based on Central-Composite design.Finally, the interface was designed after all the mathematical models were written to the software with MATLAB GUI. An application software by which PSFZ dosage and whole GT value were calculated using floc simulation in a given range of water quality parameters was obtained and followed by compiling into a standalone executable C file which was named Coaulgation Control Paramenter Prediction System Based On Fractal Theory . |
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