Wuhan University of Technology, Wuhan, Hubei 430070, China.
Wuhan University of Technology, Wuhan, Hubei 430070, China.
Sci Total Environ. 2023 Nov 20;900:165599. doi: 10.1016/j.scitotenv.2023.165599. Epub 2023 Jul 28.
Sulfur autotrophic denitrification coupled anaerobic ammonia oxidation (SAD/A) has several advantages over other denitrification processes; for example, it does not consume the organic carbon source, has low operation costs, and produces less excess sludge; however, it has certain disadvantages as well, such as a long start-up time, easy loss of bacteria, and low microbial activity at low temperature. The use of microbial immobilization technology to embed functional bacteria provides a feasible method of resolving the above problems. In this study polyvinyl alcohol‑sodium alginate was used to prepare a composite carrier for fixing anaerobic ammonia oxidizing bacteria (AAOB) and sulfur oxidizing bacteria (SOB), and the structure and morphology of the encapsulated bodies were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Subsequently, the nitrogen removal performance of the immobilized microbial carriers in the gradient cooling process (30 °C to 10 °C) was determined, and the corresponding mechanism was discussed. The results showed that the nitrate-removal efficiencies observed with granular sludge and gel embedding were at 10 °C 21.44 % and 14.31 % lower, than those at 30 °C, respectively, whereas the ammonia-removal efficiency decreased by up to approximately three-fold. The main mechanism was the 'insulation' provided by the external gel composed of PVA and SA for the internal sludge and subsequent improvement of its low temperature resistance, while protecting AAOB and SOB from oxygen inhibition, which is conducive to enriching denitrifying bacteria. In addition, the gel does not change the internal sludge species, it can shift the dominance of specific microorganisms and improve the removal efficiency of nitrogen. In summary, the immobilization of AAOB and SOB by the gel can achieve effectively mitigate nitrogen pollution in low temperature environments, thus indicating that the SAD/A process has broad engineering application prospects.
硫自养反硝化耦合厌氧氨氧化（SAD/A）相对于其他反硝化过程具有多个优点，例如不消耗有机碳源、运行成本低、产生的剩余污泥少；但也存在一些缺点，如启动时间长、细菌易流失、低温下微生物活性低。利用微生物固定化技术将功能细菌嵌入其中，为解决上述问题提供了可行的方法。本研究采用聚乙烯醇-海藻酸钠制备固定厌氧氨氧化菌（AAOB）和硫氧化菌（SOB）的复合载体，通过扫描电子显微镜和傅里叶变换红外光谱对包埋体的结构和形态进行了表征。随后，考察了固定化微生物载体在梯度降温过程（30°C 至 10°C）中的脱氮性能，并探讨了相应的作用机制。结果表明，颗粒污泥和凝胶包埋的硝酸盐去除效率在 10°C 时分别比 30°C 时低 21.44%和 14.31%，而氨去除效率则下降了近三倍。主要机制是 PVA 和 SA 组成的外部凝胶为内部污泥提供了“绝缘”，从而提高了其抗低温能力，同时保护 AAOB 和 SOB 免受氧气抑制，有利于富集反硝化菌。此外，凝胶不会改变内部污泥的种类，它可以改变特定微生物的优势，提高氮的去除效率。综上所述，凝胶固定 AAOB 和 SOB 可以有效地减轻低温环境下的氮污染，表明 SAD/A 工艺具有广阔的工程应用前景。
