Study On Phosphorus Removal By Coated Filter Media Of Bentonite

This experiment and research takes AlCl₃ as a denaturant, using natural bentonite as a carrier, causes Al³⁺ come into the bentonite's internal skeleton space doing ion exchange to make impregnation variability bentonite filter. Modified filter surface states and surface energy are different from those of unmodified filter, denaturation makes their surface characteristics changed, the surface area increased, surface active adsorption sites and active adsorption points increased too, surface adsorption capability strengthened. Through massive experiments, analysised and researched on the modified filter under different test conditions, its phosphorus waste water removal effect.Use unmodified and modified bentonite filter to conduct static contrast phosphorus removal test under conditions of different parameters. Test results show, in the static test, unmodified bentonite (after baking), its phosphorus removal rate reached to a certain extent. At 500°C, phosphorus removal rate of the unmodified bentonite reached 73.8%. Note bentonite's own strong adsorption capacity. Al³⁺ modified bentonite has good phosphorus adsorption properties, which can be applied to deep treatment to low concentrations of phosphorus-containing waste water. The waste water pH in adsorption treatment has a great effect, pH value at 6～9 helps Al³⁺ modified bentonite adsorpts phosphorus, pH at 9, phosphorus removal rate reaches the maximum. When the modified bentonite amount used (including 1.0% Al³⁺) is 5g/L, to the waste water , who's pH is 6 and the phosphorus quantity is not bigger than 11mg/L, its elimination rate achieved above 95.5%, the surplus phosphorus content in the waste water is smaller than 0. 5mg/L, has achieved our country waste water synthesis emissions level standard.In this research, also has conducted the experimental study to the influence factor of static and dynamic adsorption phosphorus removal, such as the concentration of Al³⁺ used in making modification filter material, the modification filter material roasting temperature, initial concentration of phosphorus and the pH value in the phosphorus waste water, filtration rate in the dynamic filtration,etc. Through the test, made the static adsorption isotherms of unmodified and modified bentonite filter material , with office graphics software mathematical fitting the isotherms, got adsorption types the static adsorption isotherms belongs, this thesis also made analysis and discussion on the theory of denaturing filter defluorination on the basis of comprehensive analysis of experimental data.