The Research On The Preparation Of Polysilicate Multi-metal-composite Coagulant And Application Of Numerical Simulation

In this paper,the technology of poly silicic acid and metal salt composite coagulant(Polysilicate Multi-metal-composite Coagulant referred to as "PSMC")which prepared by domestic waste(Warm paste)and fly ash was studied to deal with domestic sewage and then to verify the reproducibility and practicality of the coagulant and optimize the experimental results.Monitoring the effect of water treatment by three dimensional fluorescence spectrometer and Studying on the characteristics of flow field under different rotational speeds by computational fluid dynamics,and then the application software named prediction system of Polysilicate Multi-metal-composite Coagulant based on fractal theory is established.The main research contents are as follows:(1)Preparation of polysilicate metal salt composite coagulant material waste influence of single factor treatment and warm paste in order to optimize the experimental factors and response surface response surface to simulate the better fitting degree,get the best combination process: H2SO4 volume 35 ml,water bath temperature of 100 degrees,the heating time of 2h;(2)Through the single factor experiment and response surface optimization experiment,preparation factors of Polysilicate Multi-metal-composite Coagulant: the mole ratio of n(M)/n(Si),n(Fe+Zn)/n(Mg),n(Fe)/n(Zn),PH value,temperature and time that influence the polymerization are considered synthetically.The optimal preparation conditions is when the pH value,temperature and time of polymerization were 1.45,40 and 35 min,respectively.And The molar ratio of n(M)/n(Si),n(Fe+Zn)/n(Mg),n(Fe)/n(Zn)to prepare raw materials were:4:1,2:1,1:1,respectively.The scanning electron microscopy(SEM),X-ray diffraction(XRD),optical microscopy and UV Vis absorption spectroscopy were used to analyze PSMC,The results show that PSMC is a kind of amorphous polymer,and it has a spatial network structure,a large specific surface area,the strong capacity of sweep net capture and adsorption bridging as well as a good coagulation effect.(3)Study on the application of polysilicate metal salt compound coagulant to treatment effect of humic acid wastewater,printing and dyeing wastewater,and domestic sewage,which shows that PSMC has a wide application range;PSMC processing using sewage as theresearch object to verify the application effect of PSMC,comparing of PSMC and PAC in coagulation effect of domestic sewage treatment and selection of coagulation hydraulic conditions,and the experiments show that when the water quality in the same conditions,water treatment effect by using PSMC in the case of low dosage is better than PAC,and it was found that the 60mg/L dosage was the best coagulation effect of PSMC,the turbidity was2 NTU,the removal rate of CODcr was 81%,the removal rate of chroma and TP was 95%;The orthogonal experiment was used to study the coagulation hydraulic conditions of domestic sewage treated by PSMC.The experimental results show that in the actual operation,different hydraulic conditions should be provided according to the actual needs;Application of three dimensional fluorescence spectroscopy in the treatment of wastewater containing fluorescent substances,such as humic acid wastewater,landscape lake water,salicylic acid wastewater,the removal effect of coagulant on fluorescent substances in water can be directly observed by using the three-dimensional fluorescence spectrum.(4)The numerical simulation of the flow field in the process of experiment is carried out by using computational fluid dynamics,the flow field of six mixers was simulated by using FLUENT,the stirring speed of the mixing drum is analyzed under three conditions of a:166r/min,b:200r/min and c:300r/min respectively.According to the velocity nephogram of Z=0 and Y=0,It is found that under the condition of 200r/min,the velocity of the edge is the largest,and the lowest vortex phenomenon on the back of mixing blade;According to the simulation of velocity vector nephogram,it can be seen that when the stirring speed is300r/min and 200r/min,the phenomenon of time and space is small,and the mixing of the cylinder body is more uniform in 200r/min,which is beneficial to the coagulation;through the simulation of turbulent kinetic energy,it can be found that the greater the stirring speed,the more stable the turbulent kinetic energy in the cylinder,and the turbulent kinetic energy in the cylinder is better when the stirring speed is 200r/min and 300r/min.(5)In the floc growth model,the growth process of flocs is studied under the ideal condition,and through the simulation of the process of flocculation and flocculation in the actual operation process,the effects of different factors on the growth of the model were discussed,and the simulation of flocs with real flocs is used to illustrate the necessity of breakup and coalescence model.The mathematical model of water quality parameters,coagulation parameters and fractal is established based on the comparison of image and fractal dimension,and with the help of MATLAB GUI software,all the mathematical models are programmed,and the program is named as“ A prediction system of coagulation process of poly silicic acid metal salt composite coagulant based on Fractal Theory”.