秸秆骨架对颗粒赤泥吸附剂除磷性能的影响与作用机制

The excessive discharge of phosphorus wastewater results in not only serious environmental pollution, but also significant resources waste. The granular red mud is regarded as a promising adsorbent in the field of phosphorus recovery and reutilization from wastewater. The preliminary experiments showed that the phosphate adsorption performance of granular red mud adsorbent was effectively improved with the straw addition. However, the exact role of straw during the adsorption process is still unclear. In this project, skeleton builder is chosen as a focal point, and the influence of preparation condition on the straw skeleton structure of granular red mud adsorbent will be systematically examined. Furthermore, technologies such as sequential extraction method, Fourier transform infrared (FTIR), and X-ray diffraction patterns (XRD), will be employed to investigate the effect of skeleton builder on the immobilization of main ingredients and phosphate diffusion during the adsorption process. The interaction between granular red mud adsorbent and phosphate was also analyzed. Moreover, the performance of granular red mud adsorbent based on the straw skeleton builder in the fixed-bed column will be evaluated, and suitable measures will be suggested with the consideration of “skeleton stability” and “microbial immobilization and diversity”. These works are expected to provide new knowledge on the application of granular red mud adsorbent and waste straw.

含磷污水的大量排放不仅造成严重的环境污染，而且导致巨大的资源浪费。颗粒赤泥吸附剂在磷回收和再利用方面具有广阔的应用前景。申请人通过前期研究发现，秸秆能有效改善颗粒赤泥吸附剂的磷酸盐吸附性能。但是目前尚不清楚秸秆在颗粒赤泥吸附剂除磷过程中的作用机制。本项目以骨架构建作为切入点，分析不同制备条件下颗粒赤泥吸附剂的秸秆骨架结构特征，评估秸秆骨架结构的稳定性；利用顺序提取法、傅里叶变换红外光谱、X射线衍射等方法，考察秸秆骨架促进颗粒赤泥吸附剂有效吸附组分固定及磷酸盐扩散的作用机制，探究基于秸秆骨架的颗粒赤泥吸附剂的除磷性能及机理，阐明高效的颗粒赤泥磷酸盐吸附剂的定向构建方法；从“骨架稳定性”、“微生物多样性”的角度揭示秸秆骨架对颗粒赤泥吸附剂在固定床运行稳定性的影响及调控机制，为促进颗粒赤泥吸附剂的工业应用提供潜在的技术途径，也为高效利用废弃农业秸秆资源提供理论依据。

含磷污水的大量排放不仅造成严重的环境污染，而且导致巨大的资源浪费。颗粒赤泥吸附剂在磷回收和再利用方面具有广阔的应用前景。本项目成功利用粉末赤泥、稻草粉末及羟丙基甲基纤维素（HPMC）制备了颗粒赤泥，并将其用于磷酸盐吸附。研究结果表明，秸秆骨架结构显著影响颗粒赤泥的磷酸盐吸附性能。最佳制备条件下（粉末赤泥、稻草粉末及HPMC的质量比为71:22:7、焙烧温度为225 oC、焙烧时间为30 min），颗粒赤泥总孔容积可达到0.0375 cm3/g。这主要是由颗粒赤泥复杂的矿物相及在制备的过程中添加稻草粉末促进秸秆骨架结构生成决定的。颗粒赤泥的磷酸盐吸附性能随着吸附温度及溶液初始pH值的升高先升高后降低，其吸附过程可用Richie多级动力学模型及Langmuir-Freundlich吸附等温式描述。XPS扫描结果表明，79.01%的磷酸盐通过沉淀和离子交换形成强化学键与颗粒赤泥相结合，20.99%磷酸盐通过表面沉积的形式形成弱化学键与颗粒赤泥相结合。同时，颗粒赤泥被成功应用于固定床系统吸附磷酸盐。颗粒赤泥固定床吸附系统最大磷酸盐吸附量为84.80 mg/g，处理污水的柱床体积数高于495。利用0.5 mol/L的盐酸溶液可对颗粒赤泥进行有效解吸。拓展研究还显示，赤泥还可用于其他环境治理领域，其添加能显著改善污泥厌氧消化产甲烷性能。这是由于赤泥能够有效促进污泥中有机物的水解酸化，为产甲烷过程提供更多的底物。此外，赤泥的添加显著提高了厌氧消化系统的电导率，有效改善微生物种间直接电子传递效率。这些研究成果为高效利用废弃农业秸秆资源提供理论依据，也为促进赤泥的工业应用提供潜在的技术途径。