新型两性吸附剂制备与吸附-催化协同作用强化脱氮研究

Due to low C/N ratio, the efficiency for nitrogen removal is not satisfied in biological system. Ammonia and nitrite can be transfer to nitrogen without organic carbon in anaerobic ammoniam oxidation process, however, the cultivation and inoculation of anmmox bacteria is difficult. Moreover, the controlling of anaerobic ammonia oxidation process is hard to keep stably. In theory, the nitrogen removal can be accomplished through the redox reaction between ammonia nitrogen and nitrite. In this study, a high efficient adsorbent would be synthesized base on the amphoteric TA-Fe3+ material. Therefore, the advantage for the redox reaction of ammonia nitrogen and nitrite would be offered, and then, the high efficient amphoteric adsorbent could be on-site regenerated by the nitrogen removal reaction. In addition, the material science, adsorption and catalysis chemistry, molecular biology and analytic chemistry would be applied to accomplish the aim in this research work. The efficiency of adsorption and nitrogen removal would be investigated, and the controlling parameters would be optimized. Moreover, through modification, the novel adsorbent would be synthesized on which the adsorption and catalysis of ammonia nitrogen and nitrite could simultaneously happen. So, the nitrogen removal efficiency would be improved due to the acceleration of the ammonia nitrogen and nitrite redox reaction. Furthermore, the mechanism for the adsorption and catalysis of ammonia nitrogen and nitrite would be deeply discussed. Based on the above fundamental research, a novel partial nitritation (convert part of ammonium to nitrite)+adsorption-catalysis combined process would be set up. And then, the operation parameters would be optimized in order to acquire better nitrogen removal efficiency. In sum, the theoretic fundament for a novel nitrogen removal technology in wastewater treatment would be established due to this study.

低碳氮比是影响生物脱氮效果的主要原因。厌氧氨氧化技术虽然能够实现无碳源情况下氨氮与亚硝酸盐氮反应生成氮气，但厌氧氨氧化菌的培养驯化和保持工艺运行稳定比较困难。理论上，氨氮和亚硝酸盐氮能够直接发生氧化还原反应生成氮气而实现脱氮。本研究将综合运用材料学、吸附-催化化学、分子生物学和化学分析手段，利用丹宁酸铁能够同时吸附阳离子和阴离子的特性，制备具有高吸附性能的两性吸附剂，为氨氮和亚硝酸盐氮的氧化还原提供有利条件，并通过脱氮反应实现吸附剂的原位再生和连续使用。研究吸附与脱氮性能及最佳控制条件；进一步通过材料的改性和修饰，研究能够同时吸附和催化氨氮与亚硝酸盐氮的新吸附剂，以加速氨氮与亚硝酸盐氮的氧化还原反应，提高脱氮效率；探索氨氮和亚硝酸盐氮吸附-催化协同作用机制与强化作用；提出氨氮部分生物亚硝化与吸附-催化组合脱氮工艺，建立基于最大脱氮效率的运行模式，为污水脱氮新技术与工艺的发展奠定理论基础。

本研究用单宁酸铁和氯化铁合成制备了具有同时吸附-催化氨氮和亚硝酸盐氮功能的新型两性吸附剂单宁酸铁，考察了单宁酸铁的的吸附-催化脱氮性能，探讨了其除氮机理，提出了生物+吸附-催化组合脱氮工艺。研究结果表明：综合考虑单宁酸铁产率及其在水中稳定性，确定了单宁酸铁与氯化铁的最佳配比为1:20-1:25。场发射扫描电镜（FW-SEM）、比表面积分析仪、傅里叶红外光谱仪(FTIR)和X射线衍射仪(XRD)的分析表明，单宁酸铁表面粗糙、具有多孔性结构，比表面积、孔容和平均孔径分别为97.0 m2/g、0.073 cm3/g和66.5 nm; 单宁酸与三价铁结合的位点在酚羟基处；具有非晶相结构和金属-有机骨架材料的特性。在氨氮或亚硝酸盐氮单独存在的情况下，单宁酸铁通过吸附去除氨氮和亚硝酸盐氮，去除效率与单宁酸铁的投加量有关，当单宁酸铁与氨氮和亚硝酸盐氮的质量比（mg/mg）为200时，氨氮和亚硝酸盐氮的去除率均大于95%，当有其他阳离子或阴离子共存时，单宁酸铁对氨氮和亚硝酸盐氮的吸附具有优先选择性。在氨氮和亚硝酸盐氮共存体系中，检测出有氮气含量的增加，3小时后，氨氮和亚硝酸盐氮的去除率分别为98.1%和96.2%，氮气的转化率达到87.1%。这证明了单宁酸铁不仅具有吸附作用，而且能够催化氨氮和亚硝酸盐氮发生氧化还原反应生成氮气。这使得单宁酸铁与一般的吸附剂在吸附饱和后不需要单独再生，可以连续使用。运用吸附动力学模型、Weber-Morris方程、Langmuir和Frenundlich方程对单宁酸铁单独吸附氨氮和亚硝酸盐氮的数据进行拟合，结果显示氨氮和亚硝酸盐氮在单宁酸铁表面分别发生单分子层和多分子层的吸附，其吸附过程符合二级动力学模型，并且颗粒外部扩散和表面吸附起主要作用；氨氮与单宁酸铁的氧负离子通过静电作用结合，亚硝酸盐氮与单宁酸铁中的铁离子通过静电作用和配位作用结合。用X射线光电子光谱(XPS)和FTIR对氨氮和亚硝酸盐氮共存情况下反应前后的单宁酸进行分析，结果发现，吸附-催化前后，单宁酸铁的Fe的电子结合能发生了变化、部分官能团吸收峰发生了迁移，证明了单宁酸铁吸附-催化的核心点位是Fe-O。根据上述研究，提出了半生物亚硝化生物膜+吸附-催化+生态过滤组合脱氮工艺，为污水脱氮工艺的发展奠定了理论基础。