| The overall quality of water source in China is poor,especially the water environmental pollution.In order to supply high quality drinking water and ensure the demand of the residents’ production and living water,the secondary micro flocculation enhanced filtration technology came into being.Traditional titanium salt,iron salt and polyacrylamide will cause secondary pollution in the water source,and the residual aluminum and iron in water will have a bad effect on human health.With the development of smelting industry,the production cost of titanium salt is also decreasing.Titanium salt as a new water treatment agent has been widely studied.In this study,titanium salt is used as raw material to prepare two new titanium salt filter aids.The two kinds of titanium salt are combined with filter aids and single titanium salt filter aids by simulating micro polluted raw water with algae and humic acid in the precipitation tank of Magua water plant The experimental study of secondary micro flocculation enhanced filtration.The best titanium salt filter aids were selected by comparing the characteristics and enhanced filtration effects of three different types of titanium salt filter aids PTFC,TXFC and single titanium salt,and the filtration mechanism of the two kinds of composite filter aids PTFC and TXFC was discussed.Infrared spectra show that TXFC and PTFC form many kinds of groups,such as Fe oh and TiO groups formed by PTFC;TXFC forms new groups such as Ti-O-Ti,Ti-O and enol isomers C-O,which indicates that the effective combination of metal elements and carboxyl groups in the preparation process;SEM shows the structure of PTFC and TXFC,TXFC presents rectangular block structure;PTFC shows spiral structure The results of XPS show that the AC group is introduced into the preparation of TXFC,and the electron orbital of metal elements has more transitions.Compared with PTFC filter aids,TXFC contains more metal ions and AC groups to form chemical bonds;UV visible light The spectrum analysis shows that PTFC has strong absorption of ultraviolet light at 190-350 nm,mainly with the absorption peak of iron ions.TXFC has a strong broadband in 200-300 mm,and the migration occurs because with the increase of titanium ion dosage,the binding ability of titanium ion and AC group is enhanced,and titanium ion is transformed from low polymer to middle polymer to high polymer.The results show that the two kinds of titanium salt filter aids have good removal effect on turbidity in water.When the dosage of TXFC is 3mg/l,the turbidity of raw water is reduced from2.114 ntu to 0.191 ntu under weak acid,neutral and alkaline conditions,and the turbidity removal rate reaches 91.06%;the turbidity removal rate of PTFC filter aids is 3mg/l,alkalinity is 0.75,pH range is 8-8.5,and the turbidity of raw water inlet water is 2.29 ntu reduced to 0.273 ntu,and turbidity removal rate reaches 90.47%.This shows that TXFC filter aids have better removal efficiency for turbidity and particles.The results show that the treatment effect of the original organic matter is the best when the amount of PTFCb0.75 is added to the water before filtration,pH=8-8.5 and the dosage is 4mg/l.At this time,the DOC concentration of the effluent is 2.052mg/l,and the DOC removal rate reaches28%;for TXFC,the combined filter aid with ti/fe=4:1 is added to the water before filtration,and the dosage is added When the concentration of DOC is 3mg/l,the concentration of DOC in the water is 2.753mg/l,the DOC concentration of effluent is 2.441mg/l,and the removal rate of DOC is about 11.36%.The reason for the increase of DOC concentration in the effluent compared with that of PTFC is mainly due to the increase of the concentration of small and medium molecular organic matter caused by the introduction of acetylacetone,the hydrolysis inhibitor.The removal efficiency of two new titanium salts and filter aids was compared.PTFCb0.75>TXFC4:1.The response surface method optimized the ratio of PTFC and TXFC,the optimum dosage and pH.The optimum base degree of PTFC is 0.77,the best amount is 4.13mg/l and the optimum pH is 8.20,which is basically consistent with the single factor experiment.The optimum ratio of titanium iron to iron of TXFC is 4.06,the best dosage is 4.04mg/l and the optimum pH is 9.06.Due to the corresponding surface method,the turbidity removal rate is the response value,considering that too much TXFC is added,the dissolved organic matter in the water will rise,3mg/l is selected as the response value For the best dosage.Under the optimal mixture ratio and optimal pH of the two agents,the two kinds of filter aids were added to simulated high-speed water and humic acid micro polluted water source respectively.Through three-dimensional fluorescence analysis and liquid chromatography organic carbon detection,TXFC and PTFC had good removal effect on macromolecular organic matter.Before filtration,two kinds of filter AIDS,PTFC and TXFC,were added to enhance the filtration to biopolymer and saprophic acid The removal rates of humic acid,humic acid degradation products and low molecular neutral organic compounds were 37.22%,46.63%,-9.8%,24.6% and 53%,62%,13.8%,-61.2%,respectively.It can be seen that the removal rate of TXFC to humic acid and biopolymer is 15.78% and 16% higher than that of PTFC.Compared with the effect of the structure and colloid stability of the two kinds of compound filter aids,the particle size TXFC4:1>PTFCb0.75,TXFC4:1,TXFC4:1,the maximum fractal dimension of the flocculant formed under the optimum conditions are 2.67,and the fractal dimension of the flocculant formed by PTFCb0.75 under the optimal condition is 2.03;the effect of the two kinds of filter aids on zeta potential is PTFCb0.75>TXFC4:1,and the two kinds of composite filter aids have the effect on zeta potential as PTFCb0.75>TXFC4:1,and the two kinds of flocculants have the maximum fractal dimension of 2.67,and the The potential of zeta in the water of the compound filter aids is greatly affected by the dosage of the gel,and it is almost not affected by the change of pH.when the maximum dosage is 5mg/l,zeta potential is still less than zero point of-1.5mv;the pH and dosage have an effect on the ζ potential of the colloid in water.When the optimal dosage is 4 mg / L and pH = 8,the ζ potential of colloid in water is-1.1mv.The two filters showed a negative correlation with turbidity of sand filter effluent under the condition of increasing the dosage of the filter,and the filtration cycle was also negatively related to the size of floc.In conclusion,the combination of titanium and iron metal ions with filter aids has ideal enhanced filtration effect on the actual micro polluted water.It can degrade the macromolecular humic acid and microbial metabolites in the micro polluted water,and can judge the operation status and performance of the filter by fractal dimension and volume ratio of the floc particle size.The results of this study provide a broad prospect for the development of titanium salt filter aids in secondary micro flocculation filtration. |
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