Yu Jinlan, Huo Ran, Liu Wei, Wen Xianghua
School of Environment, Tsinghua University, Beijing 100084, China.
School of Environment, Tsinghua University, Beijing 100084, China.
Sci Total Environ. 2023 Dec 10;903:166246. doi: 10.1016/j.scitotenv.2023.166246. Epub 2023 Aug 13.
Membrane bioreactor (MBR) and nanofiltration (NF) process has been attractive in wastewater reclamation, and was set as the target process in this study. Dissolved organic matter (DOM) and trace organic contaminants (TrOCs), closely associated with water safety, are noteworthy pollutants. Though the general DOM characteristics and TrOCs removal in MBR-NF reclamation process have been reported in lab-/pilot-scale experiment, the molecular characteristics of DOM revealed by high resolution mass spectrometry, and the correlation between DOM and TrOCs have been rarely studied in full-scale MBR-NF wastewater reclamation plant. In this work, biological and NF processes contributed significantly to the removal of DOM and TrOCs, while MBR filtration contributed slightly. Spectroscopic analyses revealed that DOM with higher aromaticity and lower molecular weight were more recalcitrant along the treatment. Aromatic protein-like substances were preferentially removed comparing to humic-like substances. Fourier transform ion cyclotron resonance mass spectrometry was applied to investigate DOM transformation at molecular level. DOM molecules with higher H/C and lower O/C, especially the aliphatics and peptides, were readily biodegraded into higher‑oxygenate, highly unsaturated, and aromatic compounds. The generated species mainly included condensed aromatics, polyphenols, and highly unsaturated compounds. Filtration in MBR tended to reject higher oxygenated molecules. NF effectively removed most of the DOM molecules, especially higher oxygenated molecules with low H, N and S. The residual TrOCs in the NF effluent, including sulfamethoxazole, ofloxacin, and bisphenol A, still displayed above medium environmental risk. Significant correlations were found among organic compounds, spectral indices, and peptides molecules. Positive correlation between most of the TrOCs and several DOM parameters implied that they were synchronously removed in biological and membrane filtration processes. SUVA and FI might be potential indexes in monitoring the performance of MBR-NF process in both DOM and TrOC removal. These findings would expand the understanding of DOM and TrOCs behavior in wastewater reclamation process and simplify an in-depth system monitoring.
膜生物反应器（MBR）和纳滤（NF）工艺在废水回收利用方面具有吸引力，并且在本研究中被设定为目标工艺。与水安全密切相关的溶解有机物（DOM）和痕量有机污染物（TrOCs）是值得关注的污染物。尽管在实验室/中试规模实验中已报道了MBR-NF回收工艺中一般的DOM特性和TrOCs去除情况，但在实际规模的MBR-NF废水回收处理厂中，通过高分辨率质谱揭示的DOM分子特征以及DOM与TrOCs之间的相关性鲜有研究。在本研究中，生物处理和纳滤工艺对DOM和TrOCs的去除贡献显著，而MBR过滤的贡献较小。光谱分析表明，随着处理过程的进行，具有较高芳香性和较低分子量的DOM更难降解。与类腐殖质物质相比，类蛋白芳香物质优先被去除。应用傅里叶变换离子回旋共振质谱在分子水平上研究DOM的转化。具有较高H/C和较低O/C的DOM分子，特别是脂肪族和肽类，容易被生物降解为含氧量更高、高度不饱和的芳香族化合物。生成的物质主要包括缩合芳烃、多酚和高度不饱和化合物。MBR中的过滤倾向于截留含氧量更高的分子。纳滤有效地去除了大部分DOM分子，特别是含H、N和S较低的高含氧化合物分子。纳滤出水中残留的TrOCs，包括磺胺甲恶唑、氧氟沙星和双酚A，仍显示出中等以上的环境风险。在有机化合物、光谱指数和肽类分子之间发现了显著的相关性。大多数TrOCs与几个DOM参数之间的正相关表明它们在生物处理和膜过滤过程中被同步去除。SUVA和FI可能是监测MBR-NF工艺在DOM和TrOCs去除方面性能的潜在指标。这些发现将扩展对废水回收过程中DOM和TrOCs行为的理解，并简化深入的系统监测。
