| In this study,an experiment for treating excessive inorganic ions and harmful bacteria in drinking water was designed.This thesis will remove the inorganic ions and harmful bacteria in drinking water based on dielectrophoresis(DEP).According to different types of pollutants,the study used DEP-enhanced adsorption and DEP to remove inorganic and harmful bacteria,respectively.In DEP reactor,the excessive inorganic ions and harmful bacteria were removed from drinking water effectively and up-to-standard.The specific research and analysis are mainly divided into three parts:1.Exploration of adsorption capacity and mechanism on F~- by Hydroxyapatite(HAP).And optimize the processing conditions.HAP has the highest removal efficiency of F~- .Adsorption of F~- removal increased rapidly before 10 min and then stabilized at different initial concentrations by HAP.When the concentration of F~- was increased,putting into the same amount of adsorbent,removal rate was gradually decreased.But the adsorption capacity of HAP would increase.In the experiment of effect of HAP adsorption on F~- ,the optimum process conditions were:pH 7.0,processing time of 15 min,initial concentration of 15 mg/L.The second order kinetic model and the Langmuir isotherm provided the best correlation for cadmium adsorption onto HAP.SEM characterization results showed that the change of pH changes the surface morphology of HAP.When the pH was increased,the specific surface area of the HAP was decreased,resulting the deterioration of the adsorption capacity of the HAP.2.Removal of F~- in simulated water by using DEP-enhanced adsorption method.And optimize the processing conditions and mechanism.The optimal dosage of HAP was determined to be 6 g/L,and the removal rate of F~- by DEP-enhanced adsorption was increased compared simple adsorption under 15 V applied voltage.Explored the effect of applied voltage on the removal eff-iciency of F~- by DEP-enhanced adsorption.15 V is the optimal voltage for the treatment of F~- by DEP-enhanced adsorption.Explored the effect of processing time on the removal rate of F~- .The removal rate increased with the increased of DEP processing time,and the optimal processing time was 20 min.The removal rate of F~- was different with different initial concentrations by DEP-enhanced adsorption.When the initial concentration of F~- was lower than 10 mg/L,the residual concentration after treatment was less than 0.58 mg/L,under 6 g/L dosage of HAP,15 V applied voltage,which meets the concentration standards of F~- of the Sanitary Standard for Drinking Water(GB5749-2006).SEM characterization showed that the morphology of HAP trapped on the electrode after DEP changed greatly:HAP was connected to each other,taking wire mesh electrode wire as a starting point,forming the slender linear structure after DEP process.3.Removal of E.coli in drinking water by DEP method.And optimize the processing conditions and mechanism.Effect of applied voltage on the removal of E coli by DEP was investigated.Results show that only a lower applied voltage could have a very significant removal rate of E.coli.When the voltage was 6 V,the initial concentration of 103 CFU/mL,the removal rate of E.coli could reach 87.60%.When the applied voltage rose linearly to 15 V,the removal rate of E.coli could reach almost 100%.Effect of processing time on the removal rate of E.coli was investigate.With the increasing of processing time,the removal efficiency increased rapidly at the beginning,which could reach 87.60%at 20 min,under 6 V applied voltage,initial concentration of 103 CFU/mL.DEP had different effects on the removal of E.coli at different initial concentrations.When the initial concentration of E.coli was 2000 CFU/mL,618 CFU/mL and 21 CFU/mL,the removal rates were 87.60%,89.32%and 95.25%,respectively.The activity of E.coli after DEP was characterized.Results showed that most of the E.coli captured by the wire mesh electrodes were active when the applied voltage was 6 V,and the most E.coli were inactivated at 15 V. |
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