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题名: 出厂水余铝在给水管网中的沉积行为及形态转化研究
作者: 张玥
学位类别: 硕士
答辩日期: 2015-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 石宝友
关键词: 管垢 ; 铝沉积 ; 给水管网 ; 聚合氯化铝 ; 聚硅酸,corrosion scales ; aluminum deposition ; drinking water distribution systems ; poly-aluminum chloride ; polysilicic acid
其他题名: Deposition behavior and speciation transformation of residual aluminum in drinking water distribution systems
学位专业: 环境工程
中文摘要:
      近年来水源水污染加重,以增加混凝剂投加量为主要手段之一的强化混凝技术已成为有机微污染水源和低温低浊水处理的主要方式。若混凝过程控制不当极易造成出 厂水中余铝浓度上升,进而对人体健康造成影响。同时,余铝会在输配水过程中沉积,影响管道输水能力,增加供水能耗,影响消毒效果。当水力或水质条件等发生 变化时,沉积在管网中的铝极有可能发生二次释放。
      本文首先以实际给水管网中采集的大量不同类型的管垢样品为研究对象,深入探讨了不同水源条件下形成的管垢表层沉积物和底层硬质垢中的铝元素含量及其存在形 态,分析了铝与其它元素的相关性。为了了解不同形态铝的沉积行为,采用盘管实验和烧杯实验模拟铝在管网中的沉积行为,利用石英微晶天平对沉积量进行定量表 征,并对沉积层性质进行剖析。研究的主要内容及结果如下:
      1. 采用X射线荧光光谱和X射线衍射测定不同类型管垢样品中铝含量及含铝晶体含量。研究表明,管垢表层沉积物中铝含量明显高于底层硬质垢,且主要以无定型态存 在;而含铝晶体矿物成分主要存在于底层硬质垢中。地表水条件下形成的管垢铝含量高于地下水条件下形成的管垢铝含量,这可能与地表水处理后的出厂水中残余铝 浓度较高有关。对于表层沉积物,地下水对应的样品中含铝晶体检出率高于地表水对应的样品;而对于底层硬质垢,则反之,这表明表层沉积物中的无定型态铝有往 底层硬质垢中迁移并转化为晶体形态的趋势。利用统计方法分析铝与丰量元素相关性,结果发现,所有管垢样品中铝与铁含量呈显著负相关,而与硅元素、钾元素呈 显著正相关。
      2. 结合盘管实验、烧杯实验及石英微晶天平对不同形态铝沉积行为进行研究。结果发现,低聚态铝的沉积量最低,且其沉积层为软性水化膜,说明少量无定型态 Al(OH)3的形成。Al13最易发生沉积,且沉积层偏硬质膜,说明沉积态铝结构规则,Al13的自聚可能是其沉积的主要机理。而对于Al30,其沉积 速率低于Al13,沉积层偏软性膜,其沉积的主要机理是颗粒态铝的沉降。相对于静置条件,低速搅拌会显著强化铝的沉积。
      3. 研究了pH及聚硅酸对不同形态铝沉积行为的影响,并结合石英微晶天平对聚硅酸影响沉积的机理进行探讨。实验结果发现,pH在6.7到8.7范围内对铝沉积 影响较弱,而聚硅酸显著影响不同形态铝的沉积行为。聚硅酸易与不同形态铝迅速结合而沉积,作用机理不尽相同。Alo与聚硅酸迅速反应,且产物性质稳定。而 聚硅酸与Al13、Al30发生电中和作用而部分沉积,但随着时间的推移,体系中多核铝逐渐向单核铝转化,并与聚硅酸反应生成可溶性水合硅铝酸盐,使得溶 解态铝浓度升高。铝硅比对不同形态铝的沉积行为影响较大。
英文摘要:       Currently, pollution of source water was aggravated. Therefore, enhanced coagulation technology has become the main method to treat organic micro polluted water and water with low temperature and low turbidity. Besides, the main way to achieve enhanced coagulation is increasing coagulant dosage. Once coagulation process was with improper control, residual aluminum concentration may become higher, which further affect human health. Additionally, residual aluminum may deposit on the water distribution system, which may affect the pipeline capacity, increase energy consumption and interfere disinfection. Once hydraulic condition or water chemistry changes, deposited aluminum may second release into water.
      In this paper, firstly, different types of corrosion scales/deposits were collected from real drinking water distribution systems and investigated based on statistical analysis. The aluminum concentration and existing form in hard scales and surficial deposits, which were formed under different conditions, were analyzed, and the correlations of aluminum with other co-existing elements were presented. In order to comprehend the deposition behavior of different aluminum species, coil-pipe test and batch test were applied to simulate aluminum deposition behavior in real distribution system. Additionally, quartz crystal microbalance was applied to characterize deposition amount and the properties of deposition film. Main research contents and results are as follows:
      1. X-ray fluorescence spectrometry and X-ray diffraction were applied to investigate aluminum content and aluminum-containing crystals. The results showed that aluminum content was markedly higher in surficial deposits than in hard scales. Aluminum mainly existed in amorphous phase in surficial deposits, while aluminum-containing crystals mainly existed in hard scales. With regard to the effect of different water sources, aluminum content was higher when the raw water was surface water, which may relate to the higher residual aluminum in treated surface water. Aluminum-containing crystals in surficial deposits mainly exist in samples from groundwater source. While for hard scales, the content of aluminum-containing crystals was higher when the raw water was surface water. This phenomenon showed that the amorphous aluminum in surficial deposits had a trend of migrating and transformed into crystalline phase located in hard scales. Statistical analysis method was applied to investigate the correlation between aluminum and abundant elements. The results showed that aluminum and iron had a strong negative correlation, while silicon, potassium had strong positive correlation with aluminum.
      2. Coil-pipe test, batch test and quartz crystal microbalance were combined to study deposition behavior of different aluminum species. The results indicated that, the deposition amount of non-polymeric aluminum species was the least, and its deposition layer was soft and hydrated, which indicated the possible formation of amorphous Al(OH)3. Al13 had the highest deposition tendency, and the deposition layer was rigid and much less hydrated, which indicated the deposited aluminum might possess regular structure and self-aggregation of Al13 could be the main deposition mechanism. While for Al30, its deposition rate was relatively slower and deposited aluminum amount was relatively less compared with Al13. The deposition of particulate aluminum matters with much higher hydration state was the main mechanism. Compared with standing water condition, stirring could significantly enhance the deposition process.
      3. Polysilicic acid and pH effects on the deposition behavior of different aluminum species were investigated. Besides, quartz crystal microbalance was applied to study the deposition mechanism when polysilicic acid added. It was found that the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7; while the effect of polysilicic acid on the deposition behavior。
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34476
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
张玥. 出厂水余铝在给水管网中的沉积行为及形态转化研究[D]. 北京. 中国科学院研究生院. 2015.
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