基于建筑废物的人工湿地除磷滤料的制备及其性能

Preparation and performance of artificial wetland phosphorus removal filter media based on construction wastes

  • 摘要: 高效高容量的吸附滤料是提高人工湿地除磷效率的重要手段。以建筑废物(废混凝土和废泡沫砖)为主要原料制备多孔除磷滤料,采用X射线衍射和扫描电子显微镜对滤料主要化学组分和形貌特征进行表征,利用吸附动力学和吸附等温线试验、静态对比试验和动态试验评估了滤料对水中磷的吸附性能。结果表明:该滤料比表面积大、孔隙发达,内部微观结构为片层孔隙结构,比表面积为22.7 m2/g;其吸附过程满足拟二级吸附动力学模型和Langmuir吸附等温模型,吸附机理以单分子层物理和化学复合吸附为主,最大吸附容量达到693.21 mg/g。在总磷浓度为0.4 mg/L的静态吸附试验中,多孔滤料在4 h内对磷的平均去除率为65.38%,分别是废混凝土、废泡沫砖、陶粒、硅藻土和活性炭的4.10、1.98、3.52、2.29和1.59倍。在模拟水平流潜流湿地动态试验中,在进水总磷浓度为0.40 mg/L,水力负荷为0.48、0.96、1.20、2.40 m3/(m2·d)的条件下,多孔滤料对总磷的平均去除率分别为95.74%、93.56%、80.42%、55.34%;在水力负荷为0.96 m3/(m2·d)、进水平均总磷浓度为0.52 mg/L、连续进水45 d条件下,多孔滤料对总磷的平均去除率为92.65%。该滤料制备方法简单,除磷性能优异,还实现了对建筑废物的有效利用,作为人工湿地填料具有应用潜力。

     

    Abstract: Efficient and high-capacity adsorption materials are crucial for improving the phosphorus removal efficiency of constructed wetlands. This study focuses on preparing porous phosphorus removal filter media using construction wastes (mainly waste concrete and waste foam bricks) as the main raw materials. The filter material was characterized for their main chemical composition and morphological features using X-ray diffraction and scanning electron microscope. The adsorption performance of the filter material for phosphorus in water was evaluated through adsorption kinetics and adsorption isotherm experiments, static comparative experiments, and dynamic experiments. The results showed that the material had a large specific surface area and well-developed pore structure, featuring a layered pore structure of internal microstructure with a specific surface area of 22.7 m2/g. The adsorption process fitted the pseudo-second-order adsorption kinetics model and Langmuir adsorption isotherm model, with the adsorption mechanism being primarily monolayer physical and chemical composite adsorption with a maximum adsorption capacity of 693.21 mg/g. In static adsorption experiments with a total phosphorus concentration of 0.4 mg/L, the average phosphorus removal rate of the porous material within 4 hours was 65.38%, which was 4.10, 1.98, 3.52, 2.29 and 1.59 times higher than that of waste concrete, waste foam bricks, ceramic granules, diatomaceous earth, and activated carbon, respectively. In dynamic experiments simulating horizontal subsurface flow wetlands with an influent total phosphorus concentration of 0.40 mg/L and hydraulic loads of 0.48, 0.96, 1.20, and 2.40 m3/(m2·d), the average phosphorus removal rates were 95.74%, 93.56%, 80.42% and 55.34%, respectively. Under a hydraulic load of 0.96 m3/(m2·d), an influent average phosphorus concentration of 0.52 mg/L, and continuous inflow for 45 days, the average phosphorus removal rate of the porous material was 92.65%. The filter material had the advantages of a simple preparation method, excellent phosphorus removal performance, effective utilization of construction waste, and application potential as constructed wetland filler.

     

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