钱塘江流域水源水中有机物分子量的分布

本文采用超滤膜法,使用美国 Amicon 超滤膜对钱塘江流域杭州地区两种水源水进行了有机物分子量分布的测定。结果表明,钱塘江水源水和贴沙河水源水中总有机碳的主体有机物的分子量都在3000以下,分子量小于3000的溶解性有机物占地表水总有机碳的80%左右,传统工艺对这类有机物的去除效率较低。混凝沉淀和生物活性碳滤池相结合的工艺是钱塘江水源水处理工艺的首选。     

地下水中天然有机物对生物除铁滤柱的影响研究

采用生物滤柱对地下水进行试验研究,用膜过滤法对其出水进行了分子量分析,考察了生物除铁滤柱对不同分子量区间天然有机物的去除效果。结果表明:有机物分子量大小对出水水质有较大的影响,有机物分子量越大,铁去除率越低,DOC和UV254去除率也越低。生物滤柱对原水中分子量1 kDa的有机物的去除率为82.4%,而对分子量30 kDa的有机物的去除率只有28.5%。     

水源中溶解性有机物分子量分布特性

针对珠海市多水源的特点,选定三个不同水源进行测定分析,以确定其有机物分子量分布特性.通过一个水文年的研究结果表明:珠海市微污染水源水的共同特性是大分子量(＞10 000 Dalton)和小分子量(＜1 000 Dalton)的有机物占有机物总量的绝大多数,而处于中间范围分布的有机物相对较少.利用GC-MS联机试验分析发现传统净水工艺很难有效去除此类微污染水中的溶解性有机物.     

珠江水中有机物分子量分布及其去除研究

采用超滤膜分级方法考察了常规混凝、高锰酸钾和粉末活性炭预处理等工艺对珠江水中各级分子量有机物的去除效果。结果表明,珠江水中有机物以分子量小于1kDa的小分子有机物为主,各级分子量有机物TOC和UV254具有良好的相关性。常规混凝工艺主要去除大分子有机物,且去除率随分子量的减小而降低。高锰酸钾预处理能够全面提高各级分子量有机物的去除效果;粉末活性炭主要吸附中小分子有机物,对各级分子量有机物的去除效果与常规混凝成互补。     

杭州市水源水中有机物的分子质量分布

采用滤膜过滤法对杭州市钱塘江和苕溪两水源水四季的有机物分子质量(MW)分布进行了测定。结果表明,两水源水中有机物在不同分子质量区间的分布受季节变化的影响不是很显著;两水源水中的主体有机物为MW1ku的小分子有机物,占总有机物的80%以上,其次为MW10ku的有机物。与传统的混凝沉淀工艺相比,混凝沉淀与生物活性炭滤池组合工艺可明显提高对TOC和UV254的去除率,较适合用于杭州市水源水的处理。     

自来水厂有机物去除规律的研究

某水厂通过混凝沉淀、臭氧氧化和生物降解去除有机物,对耗氧量的总去除率在50%～75%,其中混凝沉淀工艺为25%～50%,臭氧活性炭工艺为10%～30%。混凝沉淀去除了水中大部分分子量 10 kDa的有机物,臭氧活性炭工艺对分子量3 k Da的有机物的去除效果明显,能有效去除三卤甲烷前驱物。氯气消毒后产生三卤甲烷的有机物分子量大都小于1 k Da,但分子量在1～3 kDa之间的有机物具有最强的三卤甲烷生成能力。     

预臭氧化对有机物混凝的影响

消毒副产物是饮用水安全保障技术面临的重大课题,消毒副产物前驱物的去除方法有很多种,预臭氧化就是其中的一种,但是预臭氧化对后续的混凝的影响目前尚没有统一的结论。本文采用化学极性树脂分级技术为试验手段,研完了预臭氧化对混凝去除天然有机物效果的影响,对水中有机物的各成分分布进行了表征,对预臭氧化影响混凝的机理进行初步的探讨。通过树脂分级试验发现,预臭氧化使得原水中憎水中性有机物显著增加。不经预臭氧化的原水经过混凝后DOC的含量都有所下降,DOC的去除率从高到低的顺序依次为：憎水中性有机物、憎水碱性有机物、憎水酸性有机物、弱憎水酸性有机物和亲水性有机物。臭氧投加量为1．1mg／L时,憎水中性有机物的去除率大幅度提高,去除率为95％左右;臭氧投加量为4．4mg／L时,憎水酸性有机物、弱憎水酸性有机物及其它亲水性有机物的去除率都有不同程度的提高,强憎水性有机物的去除率变化不大。     

纳滤及反渗透系统脱除有机物的试验研究

通过小型系统对多类有机物进行的脱除率试验,分析了纳滤及反渗透系统对有机物脱除率受膜脱盐率、产水通量、给水温度、给水p H值、给水有机物浓度等运行条件的影响。表明了纳滤系统对解离型有机物和难解离型有机物的脱除率受给水温度的影响明显,受有机物浓度、产水通量等影响较小;对解离型有机物的脱除率受给水p H值影响较大。验证了反渗透系统对小分子量有机物的脱除率较低,而对大分子有机物的脱除率很高。     

被有机物污染树脂复苏方法探究

在热力发电厂锅炉化学补给水处理系统中,离子交换树脂除了吸附交换水中相应离子外,还吸附了水中存在的各种有机物、铁和胶体等物质。如果这些物质在树脂再生时不能完全解析出来,积累在树脂体内,就会形成不可逆吸附。影响离子交换过程的正常进行,造成树脂颜色变深,工作交换容量下降,制水周期缩短,正洗水量增大,制水批量减少,出水品质降低等后果。     

有机物分子尺度对纳滤膜污染的影响研究

以市政污水处理厂的MBR出水作为纳滤进水,从有机物分子尺度分布的微观角度分析进水中有机物分布特征与纳滤膜污染的相关性,研究含不同分子质量的有机物水样对纳滤膜通量衰减、脱盐率以及膜表面污染的影响规律.结果表明,随着进水中溶解性有机物分子质量的减小,膜比通量衰减幅度不断增加,特别是分子质量＜1 ku的溶解性有机物引起膜通量衰减幅度最大,连续运行28 h后膜比通量下降了85.2％.电镜扫描分析进一步表明,进水中分子质量＜1 ku的有机物是造成膜有机污染的主要成分.此外,水中有机物在纳滤膜表面的累积会使纳滤膜的脱盐率有所增加.当进水中有机物分子质量在1 ku以下时,纳滤膜的初始脱盐率在94％左右,经28h连续运行后脱盐率上升了3.5％ ～4％;进水中有机物分子质量在100 ku以下时,纳滤膜的初始脱盐率为91％ ～92％,经28 h连续运行后脱盐率上升4％ ～4.5％.     

浸入式膜系统回收膜反洗水的试验研究及工程应用

为提高超滤膜系统的产水率,采用混凝/粉末活性炭/浸入式膜组合工艺,对中试超滤膜反洗水进行了回收处理。结果表明,膜反洗水中的有机物浓度较高,以DOC表征的有机物主要分布在MW30 ku和MW1 ku区间内;回收系统的平均出水浊度为0.07 NTU;当FeCl3和PAC的投量均为15 mg/L时,出水CODMn平均为2.81 mg/L,平均去除率达到了50.7%;回收系统出水的pH和微生物指标均满足《生活饮用水卫生标准》(GB 5749—2006)的要求。将该反洗水回收工艺应用于杨柳青水厂的膜处理示范工程,可使系统的产水率从79.85%提高到98.03%,可减少废水排放量达33×104m3/a。     

生物粉末活性炭/超滤组合工艺处理微污染原水

针对微污染原水中存在的有机物和氨氮等污染物,采用生物粉末活性炭/超滤(BPAC/UF)组合工艺进行处理。结果表明,当进水氨氮浓度较低时,硝化细菌活性较差,无法充分发挥生物降解作用,氨氮去除率较低,同时有机物去除率也较低;当进水氨氮浓度在0. 6 mg/L左右时,可以形成稳定的生物活性炭,组合工艺对氨氮的去除率较高,且对有机物的去除率较为稳定。进水中主要以分子质量<5 ku的有机物为主,组合工艺对这部分有机物的去除率也最高。组合工艺对疏水性物质的去除,主要依靠生物粉末活性炭的吸附降解和膜面滤饼层的截留作用。NaClO强化反冲洗可以很好地降低跨膜压差的增长速度,当NaClO浓度为400 mg/L、反冲洗时间为10min时可达到最佳清洗效果。     

Permeability of low molecular weight organics through nanofiltration membranes

The removal of natural organic matter (NOM) using nanofiltration (NF) is increasingly becoming an option for drinking water treatment. Low molecular weight (LMW) organic compounds are nevertheless only partially retained by such membranes. Bacterial regrowth and biofilm formation in the drinking water distribution system is favoured by the presence of such compounds, which in this context are considered as the assimilable organic carbon (AOC). In this study, the question of whether NF produces microbiologically stable water was addressed. Two NF membranes (cut-off of about 300 Da) were tested with different natural and synthetic water samples in a cross-flow filtration unit. NOM was characterised by liquid chromatography with organic carbon detection (LC-OCD) using a size-exclusion column in addition to specific organic acid measurements, while AOC was measured in a batch growth bioassay.Similarly to high molecular weight organic compounds like polysaccharides or humic substances that have a permeability lower than 1%, charged LMW organic compounds were efficiently retained by the NF membranes tested and showed a permeability lower than 3%. However, LMW neutrals and hydrophobic organic compounds permeate to a higher extent through the membranes and have a permeability of up to 6% and 12%, respectively. Furthermore, AOC was poorly retained by NF and the apparent AOC concentration measured in the permeated water was above the proposed limit for microbiologically stable water. This indicates that the drinking water produced by NF might be biologically unstable in the distribution system. Nevertheless, in comparison with the raw water, NF significantly reduced the AOC concentration.     

化学生物絮凝工艺对溶解性有机物的去除特性

研究了化学生物絮凝工艺对溶解性有机物的去除效果及其分子质量分布的变化特征，并分别与化学强化一级工艺、初沉池和二级生物处理工艺的出水进行对比。试验结果显示：化学生物絮凝工艺对分子质量〉2ku的有机物去除效果明显；对溶解性有机物和UV260的去除率分别为45．9％和38．7％，与城市污水二级生物处理工艺相比，其去除溶解性有机物的能力较弱；对溶解性有机物的去除是通过化学和生物作用共同实现的，其中生物作用主要表现为生物吸附作用。     

磁性离子交换树脂与超滤膜联用处理淮河原水

采用磁性离子交换树脂(MIEX)/混凝沉淀/超滤膜(UF)工艺处理淮河原水,考察了对有机物的去除特性以及MIEX预处理控制膜污染的效果.结果表明:UF出水浊度稳定在0.1NTU以下,粒径>2 μm的颗粒数平均为11个/mL,粒径>10μm的颗粒物被完全去除;组合工艺对CODMn和UV254的去除率分别为75.3%和90%,且能有效去除不同分子质量区间的有机物;系统对疏水性有机物(HOM)、弱疏水性有机物(WHOM)、荷电亲水有机物(HIC)的去除效果均较好,去除率分别为94.6%、82.7%和81.3%;组合工艺对三卤甲烷生成势(THMFP)和卤乙酸生成势(HAAFP)的去除率分别为90.7%和87.6%;MIEX预处理可有效减缓膜污染,运行期间超滤膜的跨膜压差上升缓慢,经水力反冲洗后跨膜压差就基本得到恢复.     

Transformation of organic matter and bank filtration from a polluted stream

A case study of the examination of the changes of organic matter in a small, highly polluted stream and the adjacent alluvial aquifer is presented. The investigated stream was actually a collector of effluents from baker's yeast and pharmaceutical industries. The stream was characterized by a COD of several thousands of mg O₂ l⁻¹, most of which was biodegradable organic matter. Biodegradation processes took place in the surface water, with consequent oxygen depletion in the stream. The organic matter content of the river sediment was more than 10% of its dry weight. Bank filtration of organic substances was investigated in a number of observation wells at distances of 5–150 m from the river (under different hydrological conditions). The infiltration of organic matter from the polluted stream into the aquifer was found to be significant only at hydrological conditions where the water level exceeds the altitude of the stream bed. The organic matter present in groundwater samples was mainly a humic/fulvic type, and was not degraded during the 64 days of the laboratory biodegradation experiment.     

Effect of selected metal ions on the photocatalytic degradation of bog lake water natural organic matter

Herein we report the photocatalytic degradation of natural organic matter from a bog lake (Lake Hohloh, Black Forest, Germany) in the presence of 0, 5, and 10 μmol L⁻¹ of added Cu²⁺, Mn²⁺, Zn²⁺ and Fe³⁺. The reactions were followed by size exclusion chromatography with organic carbon detection (SEC-DOC) and by measurements of low molecular weight organic acids. Addition of Cu²⁺ had the largest effect of all four studied metals, leading to a retardation in the molecular size changes in NOM: degradation of the larger molecular weight fraction was inhibited leading to reduced production of smaller molecular weight metabolites. Similarly, addition of Cu²⁺ reduced the production of formic and oxalic acids, and reduced the bioavailability of the partially degraded NOM.     

Effects of molecular weight of natural organic matter on cadmium mobility in soil environments and its carbon isotope characteristics

We investigated the role of natural organic matter in cadmium mobility in soil environments. We collected the dissolved organic matter from two different types of natural waters: pond surface water, which is oxic, and deep anoxic groundwater. The collected organic matter was fractionated into four groups with molecular weights (unit: Da (Daltons)) of <1 x 10(3), 1-10 x 10(3), 10-100 x 10(3), and >100 x 10(3). The organic matter source was land plants, based on the carbon isotope ratios (delta(13)C/(12)C). The organic matter in surface water originated from presently growing land plants, based on (14)C dating, but the organic matter in deep groundwater originated from land plants that grew approximately 4000 years ago. However, some carbon was supplied by the high-molecular-weight fraction of humic substances in soil or sediments. Cadmium interacted in a system of siliceous sand, fractionated organic matter, and water. The lowest molecular weight fraction of organic matter (<1 x 10(3)) bound more cadmium than did the higher molecular weight fractions. Organic matter in deep groundwater was more strongly bound to cadmium than was organic matter in surface water. The binding behaviours of organic matter with cadmium depended on concentration, age, molecular weight, and degradation conditions of the organic matter in natural waters. Consequently, the dissolved, low-molecular-weight fraction in organic matter strongly influences cadmium migration and mobility in the environment.     

Comparing microfiltration-reverse osmosis and soil-aquifer treatment for indirect potable reuse of water

Microfiltration (MF) followed by reverse osmosis (RO) and soil-aquifer treatment (SAT) are the two principal technologies considered for indirect potable reuse of wastewater. This study, conducted at the Northwest Water Reclamation Plant, Mesa (Arizona), evaluated MF/RO and SAT (>6 months residence time) treated tertiary effluent with respect to organics removal. Effluent organic matter was characterized as total organic carbon (TOC), by UV absorbance (UVA), solid-state carbon-13 nuclear magnetic resonance spectroscopy, and size exclusion chromatography. Several trace organic micropollutants, including EDTA, NTA, and alkylphenolethoxylate residues, were analyzed by GC/MS. The study revealed that final TOC concentrations of MF/RO and SAT are 0.3 and 1.0 mgl(-1), respectively. Based on the characterization techniques used, the character of bulk organics present in final SAT water resembles the character of natural organic matter present in drinking water. Depending on the molecular weight cut-off, RO membranes can efficiently reject high molecular weight organic matter (characterized as humic and fulvic acids). However, approximately 40-50 percent of the remaining TOC in permeates consists of low molecular weight acids and neutrals representing a molecular weight range of approximately 500Da and less. In the SAT treated effluent, EDTA and APECs were removed to approximately 4.3 and 0.54 microg/l, respectively, but were below the detection limit in the MF/RO treated effluent.