The Study On Deal With Low Fluoride Concentration In Ground-water With Series Material

The population being exposed to drinking water containing fluoride with a concentration higher than the current drinking water standard is believed to be over tens of million in China,and chronic arsenism and fluorosis pose serious social problems to our country. The objective of this study was to remove fluoride from low concentration fluoride ground-water. In this paper, a systematic study including static state and dynamic experiment.The series material including nanoparticle zeolite, diatomite, modified zeolite and composite that making up of modified zeolite and diatomite.Static Expermental:1.The defluoride test of monomer material: the results of experiment showed that na- nosized (z)XHX zeolite and YN(Y),CD10 diatomite has better effect of defluoride.2.The nanosized zeolite was modified by hydrochloric acid.Study the influential factors of defluoride including: the concentration of hydrochloric acid, ratio of solid and liquidthe, time and temperature of modified process. The results of orthogonal test showed that the sequence of main factors that influenced F--containing groundwater treatment were concentration of hydrochloric acid> ratio of solid and liquidthe >the temperature of modified process>the time of modified process. When the temperature and time of calcined was 500℃and 1 hour, the ratio of zeolite and solution was 1:50 and the concentration of modified solution was 3.6% are the optimal condition of modified. The optinal adsorb condition was: the dosage was 0.25-0.4g/L,the time of adsorbed was 25-40 min.3. A compound metal was developed by modified zeolite and diatomite. The optimal conditions for preparation and fabrication of compound material are that the proportion of modified zeolite : diatomite YN(Y) was 1:1, ball milling time was 60min. The Q0(theoretical maximum adsorption capacity) of compound metal for fluoride was 18.38 mg/g, the adsorption isotherm of fluoride was correspond with the model of Langmuir. The optinal adsorb condition was: the dosage was 0.3-0.45g/L,the time of adsorbed was 20-50 min. The compound material was most suitable for water trement of low concentration fluoride ground-water.4.Study the competitive adsorption of some familiar ions in the groundwater for fluoride,when the applied condition of modified zeolite and compound metal was the optimal condition. The sequence that influenced the effect of fluoride removal by modified zeolite was SO₄^2->NO₃^->K⁺>Mg²⁺>Ca²⁺>Cl^->HCO₃^-. The sequence that influenced the effect of fluoride removal by compound metal was SO₄^2-> NO₃^-> K⁺> Cl^-> Mg²⁺> HCO₃^-> Ca²⁺.5. Nanoparticle zeolite, modified zeolite and composite were characterized by XRD and IR.Dynamic Experiment:In the continuous-flow column experiment, concentration of the raw water, the dosage of compound metal, contact-time were important factors. The optimal condition of dynamic experimentation was that the dosage was 50g/200L, the contact-time was 15min. The treated water meets the drinking water quality standards. The results of the study showed that compound metal was promising to replace those common adsorbents because of excellent fluoride removal ability, innocuity, cheap carriers. Compound metal had gotten successfully application the practice.