Abstract:

The effects of variable ammonia concentration on the removal efficiency of organic matter and ammonia nitrogen were examined by conducting sequencing batch experiments. Meanwhile, the soluble microbial products (SMP), loosely bound extracellular polymers (LB-EPS), and tightly bound extracellular polymers (TB-EPS) of anaerobic granular sludge were analyzed by using ultraviolet-visible spectroscopy (UV-Vis), excitation emission matrix fluorescence spectroscopy (EEM), and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the removal rate of COD reduced from 94.19% to 93.33% by anaerobic granular sludge, when the influent concentration of ammonia nitrogen reached to 1000 mg·L^-1, which indicated that anaerobic granular sludge had an insignificant impact on the removal efficiency of COD. However, at the same time, the removal rate of ammonia nitrogen substantially decreased from 40.6% to 7.9%, due to its influent concentration. UV-Vis spectra analysis showed that a strong absorption band appeared at 205-210 nm scope of the LB-EPS and TB-EPS, and it was demonstrated that the LB-EPS and TB-EPS contained benzene ring and double bond structure. EEM spectra analysis showed that with increase of concentration of ammonia nitrogen, the intensity of aromatic protein adsorption peak decreased in the SMP, and the humic acid adsorption peak at E_X/E_M=370-390/420-450 nm enhanced. For the LB-EPS, the coenzyme F₄₂₀ absorption peak disappeared. It was illustrated that high concentration of ammonia nitrogen had an adverse effect on the activity of methanogens. In addition, the protein-like fluorescence peak in the TB-EPS has occurred red shift. At the ammonia nitrogen concentration of 1000 mg·L^-1, it was showed the existence of carboxyl in the LB-EPS. By using UV-Vis, FTIR and EEM spectra, the SMP, LB-EPS and TB-EPS of anaerobic granular sludge were analyzed comprehensively, which could provide scientific reference for the operation of anaerobic reactor.

Key words: anaerobic, ammonia, stability, extracellular polymeric substances, wastewater

摘要：

通过序批式试验，研究了氨氮含量变化对厌氧颗粒污泥去除有机物及氨氮效能的影响，并通过紫外可见光谱（UV-Vis）、三维荧光光谱（EEM）、傅里叶红外光谱（FTIR）对厌氧颗粒污泥的溶解性微生物产物（SMP）、疏松胞外聚合物（LB-EPS）及紧密胞外聚合物（TB-EPS）进行了分析。结果表明，当进水氨氮浓度增加到1000 mg·L^-1时，厌氧颗粒污泥对COD去除率由对照组的94.19%下降至93.33%，其对COD去除影响不明显；但NH₄⁺-N去除率由40.6%降至7.9%，去除效率明显降低。UV-Vis谱图分析表明，LB-EPS与TB-EPS在205～210 nm处出现了吸收峰，表明其中均含有苯环与双键结构，且随着氨氮浓度的增大，吸收带出现了红移。EEM谱图分析表明，随着氨氮浓度的增大，SMP中芳香蛋白吸收峰强度降低，而在E_X/E_M为370～390/420～450 nm处的类胡敏酸吸附峰增强；对于LB-EPS而言，辅酶F₄₂₀吸收峰消失，表明高氨氮浓度对产甲烷菌的活性产生了抑制作用；同时TB-EPS类蛋白荧光峰发生了红移。而由LB-EPS的FTIR谱图可知，氨氮浓度为1000 mg·L^-1时，LB-EPS中存在较多的羧酸。通过利用UV-Vis、FTIR、EEM谱图可对厌氧颗粒污泥的SMP、LB-EPS、TB-EPS进行较为全面的分析，从而为指导厌氧反应器的运行提供科学借鉴。

关键词: 厌氧, 氨氮, 稳定性, 胞外聚合物, 废水