Research On The Treatment Of Fluorine Wastewater Using Fly Ash-lime Method

With the development of industrial and agricultural production, a large number of industrial wastewater discharge to the environment,resulting in fluorine pollution problems are more prominent. The research about the removal of fluorine ion and high fluoride drinking water lowed the fluoride has been a drop of the important issues at home and abroad. At present, China's industrial in the treatment of low-fluoride technology has achieved some results, but on more than 1 000 mol/L of high concentration of fluoride wastewater have poor effect.The experiment simulated the high concentration of fluoride wastewater (> 1 000 mol/L) as the research object. The first systematic comparison the two kinds of lime - fly ash method joint process (fly ashâ†'lime coupled process and limeâ†'fly ash coupled process) deal with the high concentrations fluoride wastewater treatment, systematically study the integration process of the temperature, pH, fluoride dosage, PAM, reaction time and the coexistence of inorganic ion joint process rate effect. The main findings are as follows:1. The single factor experiment results show that chooses the pretreatment of hydrochloric acid fly ash handling the fluorine wastewater. In acidic environment, and the fly ash particle size less than 0.15 mm, the adsorption of fluoride ions in waste water is the best; Lime to the fluorine wastewater treatment of the pH of the optimal value for 6.0～7.0.2. Fly ashâ†'lime joint process research results shows that fly ash as an adsorbent in the first stage, six factors five levels orthogonal experiment, the optimal combination of orthogonal experiment is the temperature 45℃, the amount of fly ash added 15.0 g, adsorption time 90 min, PAM (mass fraction of 1%) addition 0.05 mL, pH 4.0, initial concentration of fluoride 350 mg/L; Lime as a sinking agent in the secondary precipitation phase stage, the four factor and three levels of interaction design of orthogonal experiment result showed that the interaction effect factors for the removal of fluoride is temperature, addition and combination of the time factor. This stage of orthogonal experiment with lime treatment for the optimal combination is the temperature 10℃, lime addition 0.15 g, adsorption time 60 min, pH 6.88.In the optimum combination of conditions, limeâ†'fly ash joint process containing fluorine ion concentration of 1 000 mg/L of wastewater, the effluent fluoride concentration of degrees for 20 mg/L or so, is not consistent with national level of industrial wastewater discharge standards.Coexistence ion disruption technology research result shows that cationic and single anion to fly ashâ†'lime joint process dealing with 1 000 mg/L high-concentration containing fluorine wastewater is promoting trend, its helpful for the containing fluorine wastewater treatment, and when five cationic composite levels,four anion composite levels higher than 800 mg/L, interference effect is bigger.3. Limeâ†'fly ash joint process research indicates that lime as an adsorbent in the first precipitation phase, six factors five levels of the orthogonal experimental shows that the optimal combination is the temperature 10℃, the amount of fly ash added 0.15 g, adsorption time 30min, PAM (mass fraction of 1% ) addition 0.1 mL, pH 4.0, initial concentration of fluoride 200 mg/L; Fly ash as a sinking agent in the secondary precipitation phase stage , the four factor and three levels of interaction design of orthogonal experiment result showed that the interaction effect factors for the removal of fluoride is temperature, addition and combination of the time factor, temperature, addition and combination of the pH factor; This stage of orthogonal experiment with fly ash treatment for the optimal combination is the temperature 35℃, lime addition 6.0 g, adsorption time 90 min, pH 5.54.In the optimal combination of condition, fly ashâ†'lime and joint process containing the concentration of fluorine ion 1 000 mg/L of wastewater, the effluent fluoride concentration of 4 mg/L below, is consistent with national industrial wastewater level discharge standards.Limeâ†'fly ash joint process and the interference result showed that when esisted Mn²⁺,Fe³⁺,Mg²⁺ the containing fluorine wastewater has a little influence, the containing fluorine content in the effluent fluoride concentration and the controlled trial is not big. In practical projects ion Al³⁺concentration control in 10～100 mg/L, it consistent with national discharge standards. Zn²⁺ its interference process fluoride in effect.4. Compared with the fly ashâ†'lime joint process and fly ashâ†'lime joint process deal with high concentration containing fluorine wastewater find that after limeâ†'fly ash joint process the effluent containing fluorine is consistent with the national discharge standards.