饮用水嗅味物质检测与控制技术研究进展

介绍了我国饮用水中的主要嗅味问题及其来源,总结了致嗅物质的组成与分类,并重点探讨了饮用水中嗅味物质的检测与控制技术。水中嗅味物质的检测方法主要包括感官分析、仪器分析及综合分析。其中,嗅味层次分析法是最常用的感官分析法;仪器分析中更加注重对水样的预处理技术,固相萃取是一种有效的水样预处理技术。典型致嗅物质的去除工艺主要包括活性炭吸附法、化学氧化法、生物处理法及联合法。通过介绍分析近10年的研究发现,我国需要尽快开展饮用水中致嗅物质的标准化检测方法及典型致嗅物质控制技术的研究,以形成应对不同水源、不同季节、不同致嗅物质的饮用水处理工艺,以保障饮用水安全。     

饮用水中典型嗅味问题及其研究进展

嗅味是评价饮用水水质的最直观指标之一,有效识别饮用水中的嗅味、解析嗅味产生原因以及控制嗅味,对供水行业的水质管理具有重要的意义。对饮用水中常见的嗅味类型、产生原因以及针对性的控制技术进行了总结,全面阐述了从源头到龙头过程中土霉味、腥臭味、化学味等嗅味的产生条件以及吸附、氧化、生物降解等去除技术,旨在为供水行业内饮用水嗅味预判、干预和控制提供一定的借鉴和参考。     

浅析饮用水中嗅味及其去除

随着生活水平的提高,人们对饮用水的质量提出了更高的要求。本文综合论述了嗅味这一感官指标所具有的理化意义,分析了嗅味产生的原因,为了解决饮用水中的嗅味问题,国内外都采取了多种去除方法。本文结合国内外去除嗅味的实际应用情况,探讨了若干去除嗅味的方法及其效果。     

太湖某饮用水厂嗅味物质迁移特征解析

针对近年来水源地嗅味物质频发、严重威胁饮用水水质安全的问题,对太湖某饮用水厂进行了从原水到出厂水的全流程检测,分析了原水中嗅味物质的来源、含量变化及其与水环境因子的相关性,并探究了其在水处理工艺中的去除规律。原水中的主要致嗅物质为β-紫罗兰酮(β-Ion)、2,4,6-三氯苯甲醚(TCA)、二甲基三硫醚(DMTS)以及β-环柠檬醛(β-cyc),其主要源于藻类活动以及有机物的降解。DMTS含量与TCA含量呈极显著正相关,且均与氨氮含量呈显著正相关;β-Ion含量与CODMn含量呈显著正相关,并与叶绿素a(Chl-a)含量和UV254值呈极显著正相关。在饮用水厂处理工艺中,臭氧和生物预处理对TCA和β-cyc有一定去除效果;生物活性炭滤池对主要嗅味物质具有较好的去除效果;超滤膜过滤可对DMTS与TCA进一步去除。另外,在预处理、原水长距离输送、臭氧处理和清水池储存等过程中均存在嗅味物质含量回升的问题,应受到重点关注。     

去除D江异嗅的饮用水处理工艺选择研究

为去除C市D江饮用水中的异嗅,研究了强化混凝/KMnO4预氧化、强化混凝/粉末活性炭吸附和臭氧/活性炭工艺对水中异嗅和CODMn的去除特性.结果表明,臭氧氧化是去除异嗅的关键工艺.强化混凝/高锰酸钾预氧化及强化混凝/活性炭吸附工艺对异嗅和CODMn均有一定的去除作用,需要根据水中致嗅物质的组成和有机物特性进行选择.但当硫醇硫醚类致嗅物质与土嗅素和2-MIB并存时,强化混凝组合工艺无法完全去除水中的嗅味.当进水嗅阈值<35、CODMn<8 mg/L时,臭氧/活性炭深度处理工艺可以完全去除D江水中的嗅味,并且对CODMn也有很好的去除效果,但在水质再恶化时需联合使用强化预处理等工艺方能达标.     

用粉末活性炭去除饮用水中嗅味

进行了粉末活性炭（PAC）去除饮用水中嗅味的试验。结果表明，当原水嗅阈值为90、PAC投量为40mg/L时，出水无异嗅、异味。中氯后PAC对嗅味的去除率明显低于不加氯时的去除率。     

饮用水嗅和味的感官评价方法及应用研究进展

作为一种可被直接感受到的水质指标,如何有效评价水中的嗅和味,无论对于自来水厂的制水过程还是供水行业的管理都具有重要意义。重点基于不同的评价目标,对目前饮用水嗅味评价过程中感官评价方法的选择、分类、适用条件和范围等进行了针对性的总结,并提出了针对嗅味评价过程中保证结果准确性的质量控制方法和措施,以期为供水行业内饮用水嗅味评价方法的选择和应用提供一定的借鉴。     

氧化法去除水中土臭素和2-MIB的研究进展

土臭素和2-MIB是饮用水源中最为常见的典型嗅味物质,氧化法是去除两者的重要途径。总结了氧化法去除水中土臭素和2-MIB的研究进展,并对氧化法用于控制水中嗅味的技术发展方向进行了展望。     

饮用水中的氨氮问题

对当前我国地面水环境污染状况进行了归纳,认为氨氮污染是我国饮用水处理中普遍面临的问题。对饮用水中氨氮浓度过高可能产生的水质问题进行了探讨,认为可能造成饮用水中亚硝酸盐浓度过高。国内外饮用水标准的比较表明,欧洲国家对饮用水中氨氮有严格的要求,我国对水源水的氨氮限值有规定,但饮用水标准中没有规定,应该逐步推行氨氮标准。目前去除氨氮的最好方法是生物预处理技术。     

太湖原水藻类代谢产物中嗅味物质的去除技术研究

在调研太湖原水中存在的主要致嗅物质的基础上,通过试验比选、净水方案制定与实施,确定采用粉末活性炭和臭氧—生物活性炭深度处理工艺,解决了常规工艺不能有效解决的嗅味问题。在太湖原水2-MIB浓度超出国标80倍的条件下,粉末活性炭与预处理、深度处理工艺联用,可将出厂水2-MIB浓度控制在10 ng/L以下,达到国家饮用水标准。     

臭氧预氧化技术在给水处理中的研究进展

介绍了臭氧预氧化技术在饮用水处理中的应用,包括臭氧预氧化助凝,臭氧预氧化改善浊度、色度、嗅味等感官指标,臭氧预氧化去除无机、有机污染物,臭氧预氧化对致病微生物、藻类、消毒副产物等的处理效果,以及臭氧预氧化在强化常规处理工艺过程中起到的作用。表明臭氧具有多方面的除污染效能,对给水处理工艺的发展和饮用水水质的提升有显著促进作用。同时也提出了存在的一些问题,便于今后的研究和应用中进一步改进和完善。     

水中嗅味评价与致嗅物质检测技术研究进展

随着我国新的<生活饮用水卫生标准>(GB 5749-2006)的颁布实施和2007年5月太湖水危机事件的暴发,水中溴味问题成为人们关注的热点.通常情况下,水中致溴物质的溴阈值浓度(OTC)极低并且致溴物质组成非常复杂,因而对水中致溴物质的定量分析比较困难.从感官分析法、仪器分析法和综合分析法三个主要方面介绍了国内外对水中溴味评价及致溴物质检测技术的研究进展.详细介绍了各自的测试方法和机理,并分析了其适用的范围和优、缺点,指出了今后的研究方向.     

Development of predictive models for geosmin-related taste and odor in Kansas, USA, drinking water reservoirs

The presence of taste and odor compounds can greatly reduce the quality of drinking water supplies. Because the monetary costs associated with the removal of these compounds can be high, it is impractical for most facilities to continuously treat their raw water. Instead, new tools are needed to help predict when taste and odor events may be most likely to occur. Water quality data were collected between June and October in 2006-2007 from five Kansas (USA) reservoirs in order to develop predictive models for geosmin, a major taste and odor compound; two of these reservoirs were also sampled during specific taste and odor events in December 2006 and January 2007. Lake trophic state alone was not a good predictor of geosmin concentrations as the highest average geosmin concentration was observed in the reservoir with the lowest nutrient and chlorophyll a concentrations. In addition, taste and odor events were not confined to summer months; elevated geosmin concentrations were observed in several reservoirs during the winter. Growth limitation by inorganic phosphorus appeared to be the primary determinant of geosmin production by algal cells in these reservoirs.     

Kinetics and mechanisms of formation of bromophenols during drinking water chlorination: assessment of taste and odor development

Halophenols are often reported as off-flavor causing compounds responsible for medicinal taste and odor episodes in drinking water. To better understand and minimize the formation of 2-bromophenol and 2,6-dibromophenol which have low odor threshold concentrations (OTCs, 30 and 0.5 ng/L, respectively) a kinetic data base for the chlorination and bromination of phenols was established by combination of kinetic measurements and data from literature. Second-order rate constants for the reactions of chloro- and bromophenols with chlorine and bromine were determined over a wide pH range. The second-order rate constants for bromination of phenols are about three orders of magnitude higher than for chlorination. A quantitative structure activity relationship (QSAR) showed a good comparability of second-order rate constants from this study with those published previously for different phenol derivatives. The quantification of product distribution of the formed halophenols demonstrated that chlorine or bromine attack in ortho position is favored with respect to the para position. A kinetic model was formulated allowing us to investigate the influence of chlorine dose and some water quality parameters such as the concentration of phenol, ammonia, bromide and the pH on the product distribution of halophenols. The kinetic model can be applied to optimize drinking water chlorination with respect to phenol-born taste and odor problems. In general, high chlorine doses lead to low concentrations of intermediate odorous chlorophenols and bromophenols. An increase in the ammonia or phenol concentration leads to a higher consumption of HOCl and therefore greater final concentration of intermediate bromophenols. The presence of higher bromide than phenol concentration also facilitates the rapid bromination pathway which leads to further bromination of 2,6-dibromophenol to higher brominated phenols. Laboratory-scale experiments on taste and odor formation due to the chlorination of phenol- and bromide-containing waters have confirmed the trend of the model calculations.     

高锰酸钾与粉末活性炭联用去除饮用水中嗅味

针对太湖B支流水体发臭现象严重、采用常规工艺处理很难去除嗅味物质的情况，通过试验考察了单独投加高锰酸钾、单独投加粉末活性炭以及高锰酸钾与粉末活性炭联用三种方法对嗅味的去除效果。静态及生产性试验结果表明：高锰酸钾与粉末活性炭联用工艺的除嗅效果最好，当高锰酸钾投加量为0．5mg／L、粉末活性炭投加量为40mg／L时，沉后水的嗅阈值仅为5，去除率达到了98．8％，并且可节省粉末活性炭投量约20％。此外，高锰酸钾与粉末活性炭联用对藻类也有较好的去除效果。     

Ultrasonically induced degradation of 2-methylisoborneol and geosmin

2-Methylisoborneol (MIB) and geosmin (GSM) are taste and odor compounds produced by cyanobacteria in surface waters. While the strong odors and musty flavors of MIB and GSM are generally associated with poor water quality, the removal of these semi-volatile compounds presents a significant challenge to drinking water providers. Likewise in aquaculture, accumulation of these compounds in fish meat leads to quality problems and reduces marketability. Conventional water treatments are ineffective at removing low concentration of odor compounds. We report herein ultrasonic irradiation at 640 kHz leads to rapid degradation of MIB and GSM. While radical processes generally dominate during ultrasonic-induced degradation, pyrolysis appears to be responsible for a significant fraction of the observed degradation. Several pyrolytic products from MIB and GSM have been identified and degradation pathways are elucidated. The degradation of MIB and GSM follows the first-order kinetics and the rate constants are 0.07 and 0.12 min(-1), respectively. These results suggest ultrasonic irradiation maybe applicable as an effective method for removal of taint compounds from potable water supplies and fish farms.     

国内外臭氧活性炭工艺在饮用水处理中的应用实例

介绍了国内外的臭氧活性炭工艺在饮用水处理中的实例,给出了各实例的工艺参数、运行效果.认为现阶段在原水轻度污染时,可单独采用活性炭过滤工艺;原水有季节性嗅和味污染时可投加粉末活性炭;污染严重时可采用O3/GAC或O3/BAC技术甚至O3/IBAC技术,必要时增加O3预氧化,以确保出水水质达标.     

Drinking water treatment options for taste and odor control

The effectiveness of drinking water treatment options for eliminating seasonal taste and odor events caused by phytoplankton blooms in the source water were evaluated. Dissolved air flotation (DAF), conventional gravity sedimentation (CGS), ozonation and granulated activated carbon (GAC) filtration processes were studied in pilot plant-scale experiments. Clarification by DAF consistently produced water with lower turbidity and particle counts (NP > 2.0 μm/ml) than CGS. Mean particle counts detected in water following DAF and CGS treatment were 3600 and 7500 particles/ml, respectively. The absolute abundance of phytoplankton in the source water was the single most important factor influencing DAF and CGS removal efficiency. Removal efficiencies for both processes were poorer at low source water biomass (near 250 μg/l) than at higher biomass concentrations (1750 μg/l). For the eight phytoplankton taxa present in the source water, DAF and CGS removal ranged from 29–85% and 21–49%, respectively. With the exception of the total nanoplankton for which removal by both processes was comparable, all other taxa were removed more efficiently by DAF than CGS. Flavor profile analysis (FPA) indicated that DAF alone could not completely mitigate the strong fishy, musty odors associated with some phytoplankton blooms. Ozone altered the fishy odor to an undesirable “plastic-like” odor. Only filtration through GAC/sand filters removed all odors. Removal of soluble constituents such as color and total organic carbon (TOC) by DAF and CGS were comparable for most of the year. During phytoplankton blooms, however, TOC removal by DAF was significantly greater than by CGS. TOC and color removal were substantially greater through GAC than through anthracite filters. A combination of DAF clarification and GAC filtration was the most effective treatment combination for removal of particulates, color and taste and odor compounds.     

Implications of sequential use of UV and ozone for drinking water quality

The formation of bromate levels exceeding the drinking water standard of 10 microg L-1 may impose the reduction of ozone doses used in the treatment of drinking water. This paper illustrates the procedure of evaluating the use of reduced ozone doses while implementing an additional UV disinfection step for an actual drinking water treatment plant. Ozonation was performed at low ozone doses in bench-scale experiments with a pretreated river water from the Paris area (France). At the low ozone dose of 0.5 mg L-1, bromate formation could be kept below 0.4 microg L-1, while inactivation of vegetative bacteria and UV-resistant viruses was calculated to exceed 5 log units, and a substantial decoloration (31% of the absorption at lambda=254 nm) was achieved. Based on the measured transient ozone and OH radical concentrations, the oxidation of micropollutants was calculated. Fast reacting micropollutants containing phenol, amine or double bond moieties, such as sulfamethoxazole, diclofenac and 17-alpha-ethinylestradiol, were completely oxidized. Slow-reacting synthetic micropollutants, e.g., atrazine, iopromide and methyl tertiary butyl ether (MTBE), were oxidized by only 20%, 20% and 10%, respectively, and the taste and odor compounds 2-methylisoborneol (MIB) and geosmin by 40% and 50%, respectively. The addition of an UV treatment step to the existing treatment train, which should guarantee disinfection of ozone-resistant pathogenic microorganisms, including Cryptosporidium parvum oocysts, has negligible effects on water matrix components but may induce significant transformation of micropollutants. Overall, the combination of ozonation at reduced doses and UV treatment leads to an improved water quality with regard to disinfection, oxidation of micropollutants and minimization of bromate.