Li Kai, Wang Xiao-Dong, Huang Ting-Lin, Li Shu, Liu Shuang
Key Laboratory of Environmental Engineering, Shaanxi Province, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Huan Jing Ke Xue. 2019 Jan 8;40(1):185-191. doi: 10.13227/j.hjkx.201805169.
Quantity and quality of dissolved organic matter (DOM) in source water are critical factors affecting both the drinking water quality and operation of the water treatment process. As major water sources for many cities, deep reservoirs usually suffer seasonal thermal stratification, which has a significant influence on the fate and transport of many contaminants including iron, manganese, ammonia and DOM. This study focuses on the variation of properties and the fouling potential of DOM in a deep-source water reservoir during the thermal stratification period. Excitation-emission matrix (EEM) fluorescence spectra and ultraviolet absorption spectra were used to characterize the DOM. The results indicate that the quantity and quality of DOM vary with the water depth due to thermal stratification. The DOC of epilimnion is lower than that of the metalimnion and hypolimnion due to photochemical degradation. Moreover, organic matter released by phytoplankton, such as algae, play an important role in the DOM composition. Therefore, the DOM of the epilimnion exhibits a lower aromaticity, lower fluorescence intensities of Component 1 (i.e., fulvic-like substance) and Component 2 (i.e., humic-like substance), and higher fluorescence intensity of Component 3 (i.e., tryptophan-like substance). The DOM of the metalimnion is dominated by runoff input and therefore the concentration, aromaticity, and fluorescence intensities of Components 1 and 2 are higher. In terms of membrane fouling, total fouling caused by the DOM of the epilimnion is the largest, but its reversibility is better. The DOM of the metalimnion and hypolimnion results in lower total fouling but poor reversibility. The analysis of the fate of different fluorescence components during ultrafiltration suggests that the UF shows a relative high rejection rate for Component 3, which could be readily removed by backwash, whereas Component 1 and Component 2 retained by the membrane are difficult to be removed by backwash.
源水中溶解有机物（DOM）的数量和质量是影响饮用水水质和水处理工艺运行的关键因素。作为许多城市的主要水源，深层水库通常会出现季节性热分层，这对包括铁、锰、氨和DOM在内的许多污染物的归宿和迁移有重大影响。本研究聚焦于深层水源水库热分层期间DOM的性质变化及其污染潜力。采用激发-发射矩阵（EEM）荧光光谱和紫外吸收光谱对DOM进行表征。结果表明，由于热分层，DOM的数量和质量随水深而变化。由于光化学降解，表层水的溶解性有机碳（DOC）低于温跃层和底层水。此外，浮游植物释放的有机物，如藻类，在DOM组成中起重要作用。因此，表层水的DOM具有较低的芳香性、较低的组分1（即类富里酸物质）和组分2（即类腐殖酸物质）荧光强度以及较高的组分3（即类色氨酸物质）荧光强度。温跃层的DOM以径流输入为主，因此组分1和组分2的浓度、芳香性和荧光强度较高。在膜污染方面，表层水DOM引起的总污染最大，但其可逆性较好。温跃层和底层水的DOM导致的总污染较低，但可逆性较差。超滤过程中不同荧光组分归宿的分析表明，超滤对组分3的截留率相对较高，可通过反冲洗轻易去除，而被膜截留的组分1和组分2则难以通过反冲洗去除。
