超滤/纳滤双膜工艺处理苦咸水过程中DOM三维荧光特征分析

为探明“超滤-纳滤”双膜深度处理工艺处理苦咸水过程中DOM组分三维荧光特征的变化规律，采用三维荧光光谱研究了双膜工艺净水过程中DOM组分变化，发现原水中主要含有两个强度较高的尖峰和两个强度较低的尖峰，随着净水的流程，水样中的荧光峰值逐渐减弱。采用平行因子分析的方法对净水过程中的水样进行了定量分析，在对各水样进行三线性分解的过程中发现水样中主要含有以高激发光类色氨酸和低激发光类色氨酸为代表的类蛋白物质，以紫外类富里酸和可见类富里酸为代表的类富里酸两类因子，并通过水样中各因子的最大荧光峰强度的变化分析了DOM组分的变化规律，其中原水的类蛋白物质因子和类富里酸因子的荧光峰强度分别为0.351 08和0.175 55，类蛋白物质荧光峰的荧光强度大于类富里酸荧光峰，说明原水受到了一定程度外源有机物的污染。在经过水厂原有“混凝-沉淀-过滤”的工艺处理后，DOM的去除效果不佳，类蛋白物质在经过常规工艺处理后仅下降了22.27%，而对于类富里酸具有一定的去除效果，下降了47.57%。“混凝-沉淀-过滤”的常规工艺中未完全去除的DOM将进入“超滤-纳滤”双膜法净水工艺，双膜法工艺中超滤单元对DOM没有很好的去除效果，主要起预处理作用，保障进入纳滤单元的水质；对DOM去除起主要作用的是纳滤单元，经纳滤单元处理后，水中DOM大幅下降，两类因子的荧光峰强度分别为0.013 67和0.002 56，与原水相比，类蛋白物质下降了96.11%，类富里酸物质下降了98.54%。因此，在使用“超滤-纳滤”双膜法工艺处理苦咸水的过程中，应该注意在前处理中选用合适的预氧化处理以加强常规工艺对DOM的去除，在保证除盐效果良好的情况下以减轻DOM对膜污染的影响，本研究将为双膜法的推广应用及其膜污染的控制提供进一步理论基础和科学依据。

Three-Dimensional Fluorescence Characteristics Analysis of DOM in the Process of Treatment of Brackish Water by Ultrafiltration-Nanofiltration Double Membrane Process

In this paper, three-dimensional fluorescence spectroscopy was used in order to find out the three-dimensional fluorescence characteristics of DOM components during the treatment of brackish water by the “ultrafiltration-nanofiltration” dual-membrane water treatment process. Raw water mainly contains two high-intensity spikes and two low-intensity spikes. With the progress of the water treatment process, the fluorescence peaks in water samples gradually weaken. Quantitative analysis was performed on the water samples in the process of water purification by parallel factor analysis. It was found that the water sample mainly contains protein-like and fulvic-like factors. The variation of DOM components was analyzed by the maximum fluorescence peak intensity of each factor in the water sample. The fluorescence peak intensities of protein-like factors and fulvic-like factors in raw water were 0.351 08 and 0.175 55, respectively. The fluorescence intensity of the protein-like fluorescence peak is greater than that of the fulvic acid-like fluorescence, which indicates that the raw water has been contaminated by external organic matter. After the conventional process, the removal of the protein-like factors and the fulvic acid-like factors was 22.27% and 47.57%, respectively. The DOM that is not completely removed in the conventional process will enter the “ultrafiltration-nanofiltration” dual-membrane water treatment process. The ultrafiltration unit does not have a good removal effect on the DOM, which is a pretreatment to ensure that the water quality could meet the requirements of the nanofiltration unit. The removal of DOM is mainly contributed by nanofiltration unit. After the nanofiltration treatment, the DOM in the water is greatly reduced. The fluorescence peak intensities of the two factors were 0.013 67 and 0.002 56, respectively. Compared with the raw water, the protein-like substances have decreased 96.11%, fulvic-like substances decreased by 98.54%. Therefore, in treating brackish water by dual-membrane process, the proper pre-oxidation treatment should be designed to enhance the removal of DOM to reduce the impact on membrane fouling. This paper will provide a further theoretical basis for the promotion of the dual-membrane process and the control of membrane fouling.