改性粉煤灰处理低浓度含磷废水的研究

Study on treatment of low concentrated phosphorus containing wastewater by modified fly ash

以酸改性粉煤灰为吸附剂,处理低质量浓度(1mg/L左右)磷酸盐溶液,探讨了改性剂的种类、改性剂用量、吸附剂用量、反应时间、pH以及温度对除磷效果的影响。结果表明:(1)经过酸改性后粉煤灰的磷去除率显著提高,而且硫酸改性粉煤灰的除磷效果更好,磷去除率最高可达97.68%。(2)最佳条件:选择硫酸用量为5mL/g进行改性,硫酸改性粉煤灰投加量为2.0g,反应时间为60min,pH为7.2～10.8,温度为25℃(即室温)。(3)改性粉煤灰对磷的吸附更符合Freundlich吸附等温模型,既有物理吸附,也有化学吸附,并以Ca、Mg氧化物与磷形成磷的沉淀物为主。

The adsorption of low phosphate contained wastewater by modified fly ash was performed to investigate the effect of modifier types and quantity,adsorbent dosage,pH,reaction time and temperature on phosphorus removal efficiency.The results showed that the performance of fly ash was greatly improved after acid modification;sulfuric acid was better than hydrochloric acid in fly ash modification,phosphorus removal rate of sulfuric acid modified fly ash could reach to 97.68%.The optimum treatment conditions were 5 mL/g of sulfuric acid,modified fly ash 2.0 g,pH 7.2-10.8,adsorption at 25 ℃ for 60 min.The adsorption of phosphorus by modified fly ash could be described by Freundlich isotherm,indicating both physical adsorption and chemical adsorption were happened in the adsorption process,in which the phosphorus was forming a chemical precipitate with oxides of Ca and Mg.