The Performance Evaluation for the removal of Phosphates in the Effluent from Wastewater Treatment Plant using Zeolites
|關鍵字:||天然沸石;化學沉澱;磷酸鹽;吸附;natural zeolite;chemical precipitation;phosphate;adsorption|
In this research, we used natural zeolites as adsorbents to adsorb phosphates in the effluent, and we chose the effluent from the sewage treatment plants of some Central-Taiwan Science Park and synthetic phosphate solution as our research targets to study the adsorption behavior of phosphates.the effects of natural zeolite on the adsorption capacity of phosphate and the equilibrium time of adsorption were investigated.the effects of natural zeolite on the removel of phosphate in effluent from wastewater treatment plant werw evaluated. Research results showed that the optimum pH value of natural zeolite for phosphate removal efficiency is 9,and the Langmuil adsorption model can be used to describe the adsorption of phosphate in natural zeolite by Langmuir isothermal adsorption model.research results of adsorption experiments show that when the reaction temperature,pH value,adsorbent and adsorbate conditions are the same the adsorption time shortened to about one hour; and the result was faster adsorption rate and shortened adsorption equilibrium time. therefore, it proved the adsorption behavior of phosphates by natural zeolites could reach saturation in a very short period of time, and reaction rate and operating factors were in accordance with quasi-second-order dynamic model. In this research, we used natural zeolites to remove phosphates in the effluent from the wastewater treatment plants of some Central-Taiwan Science Park. There were two phosphate removal mechanisms we found from the research results. One of them was that it’s beneficial to remove phosphates when the initial pH value of the reaction solution was 9. And this can be inferred from the changes of its pH values that the mechanism of natural zeolites’surface functional groups replacing phosphates in the effluent was an adsorption reaction. The other mechanism was that , under the alkaline condition (pH 9), the exchangeable Ca2+, OH-, and PO3-4 could be precipitated by natural zeolites and got rid of.