嗅味层次分析法对饮用水中嗅味的识别

介绍了嗅味层次分析法（FPA）培训程序及其在饮用水嗅味识别中的应用案例。结果表明，按照FPA方法选择并培训的测试小组，对于实际水样中的异嗅味能够进行明确的定性和定量分析；FPA小组经嗅阈值及强度训练后，对典型土霉味物质（2-甲基异莰醇，MIB）和氯味物质NaClO的嗅阈值可分别达到4．82ng／L和0．03mg／L，同时检测出的嗅味强度与嗅味物质浓度间的关系符合Weber—Fechner Law关系式（R^2分别为0．97、0．99），且具有较好的重现性。采用该方法测定了北方某水厂各工艺段水样的嗅味变化情况。结果表明，FPA法可较好地用于评价水厂工艺对常见嗅味物质的处理效果，能够为水厂的运行提供可靠的感官分析手段。     

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.     

水源藻类和底泥对典型嗅味物质的耦合影响

通过模拟试验研究了铜绿微囊藻、底泥以及两者的组合对水源产生典型嗅味物质——2-甲基异莰醇（2-MIB）的影响。结果表明,微囊藻在生长过程中不产生2-MIB;底泥中积存了大量的2-MIB,在厌氧状态下其会释放到水中,同时扰动也会导致底泥中的2-MIB发生快速释放;底泥能够促进微囊藻的生长,而微囊藻进入衰退期后会导致水体产生厌氧状态,促使底泥释放出2-MIB,水中的2-MIB浓度达到了594 ng/L。这项研究对于掌握湖泊水源中典型嗅味物质的产生规律以及采取措施保障供水安全具有重要的指导作用。     

Developing hexanal as an odor reference standard for sensory analysis of drinking water

There are many analytical and sensory methods to analyze drinking water for flavor and off-flavors before it reaches consumers. Flavor profile analysis (FPA) is one of the most comprehensive methods. A well-trained panel is essential for FPA and although taste standards are well established, FPA training lacks an odor reference standard. In search of an odor reference standard, four different panel groups were trained and tested for n-hexanal at various concentrations (1-1000 microg/L) over 14 months. The Weber-Fechner plots for n-hexanal showed a linear and overlapping relationship for all panels. Analytical measurements demonstrated that the headspace concentration of n-hexanal was constant after 5 sniffs at 45 degrees C and it remained constant during FPA sessions for up to 4 h. The panelists liked the grassy odor of n-hexanal, which did not result in fatigue, and testing demonstrated that approximately 95% of the population can detect n-hexanal's odor. n-Hexanal is proposed as an odor reference standard for FPA training to define odor intensities because it is chemically stable, follows Weber-Fechner law, mimics grassy odors found in drinking water, and was acceptable to the human panelists.     

Significance of attached cyanobacteria relevant to the occurrence of musty odor in Lake Kasumigaura

The microorganisms and compounds causing musty odor in the second largest lake in Japan, Lake Kasumigaura, where the water is used for drinking, fisheries and agricultural purposes, were examined during the severe occurrence of musty odor in 1989 and 1990. This study was undertaken to determine the microorganisms and their metabolites responsible for the musty odor. Phormidium tenue, which has been reported to be the main contributor of the odor in Lake Kasumigaura, was isolated. Furthermore, four monoxenic strains of the odor producing attached cyanobacteria, Phormidium viscosum, Lyngbya allorgei, Oscillatoria splendida and Phormidium uncinatum, were isolated from submerged rocks and sediments in the lake. All of the four attached strains produced only geosmin, which was confirmed by gas chromatograph/mass spectrometer analysis, in the monoxenic cultures. In particular, we confirmed for the first time that P. viscosum, L. allorgei and P. uncinatum produced geosmin. Both the planktonic Phormidium tenue, a well known 2-methylisoborneol (MIB) producer and geosmin-producing attached cyanobacteria were closely associated with the occurrence of musty odor in Lake Kasumigaura.     

臭氧氧化去除水中致嗅物质的研究

以典型的致嗅物质二甲基异茨醇(2-MIB)为代表,考察了臭氧氧化工艺去除水体嗅味的效能.试验结果表明:臭氧投量为1.5 mg/L时,蒸馏水和自来水中2-MIB的氧化降解率分别为57.3%和54.2%.水中臭氧浓度和pH值的升高可以明显提高工艺对2-MIB的去除率,臭氧投量从1.0 mg/L提高至2.0 mg/L后,2-MIB的去除率由43.9%上升至72.8%;当溶液分别由弱酸性(pH=4.0)升高至中性偏酸(pH=6.5)以及由中性偏碱(pH=7.5)升高至弱碱性(pH=9.0)时,2-MIB的去除率分别提高了24.9和21.8个百分点.水中腐殖酸的浓度不同时对反应体系的影响不同,促进与抑制作用并存.     

高锰酸钾复合药剂去除放线菌嗅味研究

考察了高锰酸钾复合药地放线菌引起土霉嗅味之污染水样的混凝土处理效果，并与预氯化、单纯混凝的处理效果进行了对比。结果表明，单纯混凝土对放线菌引起的溴味污染基本没有去除；预氯化不但不能降低水和嗅味，且在一定投量时反而会使出水的嗅味强度增加；而高锰酸钾复合药剂预处理能显著降低出水的嗅味强度，且能在很大程度上降低水体的有机污染程度。     

饮用水中二甲基异莰醇的应急处理技术研究

针对郑州市S水厂原水二甲基异莰醇(2-MIB)季节性升高问题,采用在原水中投加粉末活性炭(PAC)或二氧化氯(ClO2)的应急处理技术。结果表明,在原水泵站投加PAC可以有效控制水体的臭味;与单层石英砂滤层相比,石英砂加活性炭滤层对2-MIB的去除率可增加56%;为防止活性炭吸附效率降低,应避免PAC与ClO2同时使用。     

Analysis of chemicals and energy consumption in water and wastewater treatment,as cost components: Case study of Oslo,Norway

Adopting a systems-approach to an urban water and wastewater system, while applying a triple bottom line strategy to management, entails a careful analysis of all the sub-systems and components thereof with a view to improving service levels, optimising expenditure, augmenting investments, and also reducing the life-cycle environmental impacts associated with setting up, maintaining and operating the system. The scope for optimising expenses is system-wide, though it varies from one sub-system to another, depending on inherent lock-ins and external factors beyond the direct control of the water and wastewater utility. Optimising the consumption of energy and chemicals and improving the cost-efficiency thereof, is always on the agenda of water treatment plants (WTPs) and wastewater treatment plants (WWTPs). This paper analyses the consumption of and the expenditure on chemicals and energy at Oslo's WTPs and WWTPs over time. Energy and chemicals for water and wastewater treatment, on an average account for 10.8% of the total operational expenses in the water supply sub-system and 13.7% for the wastewater handling sub-system. There is a perceptible increase in this share from 5.2% in 2004 to 14.9% in 2009 for water and 12.3% to 14.2% for wastewater. Chemicals cost more than energy for the WWTPs, while it was the other way round for the WTPs. The total real cost of energy and chemicals per cubic metre, in year-2007 currency, was between 4 and 5.2 Euro cents for the WTPs, and between 1 and 4.5 Euro cents for the WTPs. The total (WTP + WWTP) per-capita real costs of energy and chemicals, expressed in year-2007 currency, rose from around 10 Euros in year 2000 to about 12.2 Euros in year 2007.     

Biodegradation of 2-methylisoborneol by single bacterium in culture media and river water environment

2-Methylisoborneol (2-MIB) is a typical odorant in water sources. It is difficult for conventional water treatment to remove it. In this study, three strains capable of removing 2-MIB were isolated from activated carbon of sand filter. They were identified to be Shinella zoogloeoides, Bacillus idriensis and Chitinophagaceae bacterium based on 16S rRNA gene sequence analysis. The biodegradation of 2-MIB was improved with the presence of external carbon (glycerol, glucose, etc.). In the period of 20 days, Bacillus idriensis can remove 2 mg L^?1 2-MIB to 368.2 and 315.4 μg L^?1 in mineral salts medium without and with glycerol. Chitinophagaceae bacterium can remove it to 265.6 and 185.4 μg L^?1 without and with glucose. The enzymatic activity of B. Idriensis was lower when external carbon coexisted with 2-MIB. This indicated that a carbon source can inhibit the use of 2-MIB, but it can provide rich nutrients for the growth of bacteria.     

HS-SPME-GC法测定水中典型嗅味物质

研究了气相色谱仪（GC）测定水中典型噢味物质（土臭素、2-甲基异茨醇、2-甲氧基-3-异丙基吡啶、2-甲氧基-3-并丁基吡嗪和2，4，6-三氯苯甲醚）的改进方法。采用新型顶空-固相微萃取（head-space solid-phase microextraction，HS—SPME）方法对水样进行前期富集处理，然后利用气相色谱氢离子火焰检测器（FID）进行测定。在优化试验条件下对嗅味物质的测定结果显示，5种嗅味物质的峰面积与其浓度有较好的相关性，其相关系数〉0．87；该方法对5种嗅味物质的检出限值较低，其中对土臭素的检出限为0．4ng/L。改进后的测定方法适用于气相色谱仪，操作简单省时，对于推广嗅味物质的检测具有重要的实际意义。     

O3／H2O2艺去除饮用水中2-MIB的效能与机制

以2-甲基异莰醇（MIB）为嗅味物质的代表物,采用过氧化氢／臭氧氧化（O3／H2O2）工艺去除水中嗅味物质,考察了O3／H2O2工艺对水中2一MIB的去除效能与主导作用机制。研究表明,投加H2O2显著提高了单独0,氧化对2-MIB的去除效能,H2O2与O3最佳物质的量比为0．3：1,且2-MIB去除效果随pH值的升高而升高。叔丁醇对2-MIB的去除表现出显著的抑制作用,在O3氧化2-MIB过程中,除O3分子氧化2-MIB外,O3在水中自分解产生的强氧化性的羟基自由基（HO·）也具有协同氧化作用。不同浓度的天然有机物（NOM）对2-MIB去除效果的影响不同,较低浓度的NOM促进了2-MIB的去除,但随着其浓度的升高,2-MIB去除率明显降低。O3／H2O2工艺对水中2-MIB表现出良好的去除效果,是强化去除水中2-MIB等致臭微量有机物的重要工艺。     

House characteristics and condition as determinants of visible mold and musty odor: Results from three New Zealand House Condition Surveys in 2005, 2010, and 2015

This study assessed associations between house characteristics and mold and musty odor, using data from three consecutive (2005, 2010, and 2015) New Zealand House Condition Surveys, involving a total of 1616 timber-framed houses. Mold, musty odor, and house characteristics were assessed by independent building inspectors. We used multivariate logistic regression analyses mutually adjusted for other house characteristics for each survey separately. Positive and independent associations were found with tenure, ventilation, insulation, and envelope condition for both mold in living and bedrooms and musty odor. In particular, we found significant dose-response associations with envelope condition, ventilation, and insulation. Odds of mold increased 2.4–15.9 times (across surveys) in houses with the worst building envelope condition (BEC; p < 0.05–0.001 for trend); optimal ventilation reduced the risk of mold by 60% and the risk of musty odor by 70%–90% (p < 0.01 for trend). Other factors associated with mold and musty odor included: tenure, with an approximate doubling of odds of mold across surveys; and insulation with consistent dose-response patterns in all outcomes and surveys tested (p < 0.05 for trend in two surveys with mold and one survey for odor). In conclusion, this study showed the importance of BEC, ventilation, and insulation to avoiding harmful damp-related exposures.     

Relationship between intensity, concentration, and temperature for drinking water odorants

Odor analyses experiments indicated that, for the concentrations and temperatures tested, odor intensity was a function of both aqueous concentration and water temperature for water containing 1-butanol, free available chlorine, geosmin, n-hexanal, 2-methylisoborneol, and trans-2, cis-6 nonadienal. At weak odorant concentrations (approximately 4 on the flavor profile rating scale) the perceived odor intensity of these six chemicals was greater when the temperature was 45 degrees C than was 25 degrees C. Both of these temperatures are commonly encountered by consumers when they use tap water. Odor response to water containing isobutanal was affected by concentration but not water temperature. Experiments also revealed that reduction in aqueous concentration did not consistently reduce odor intensity; for some aqueous concentrations and chemicals an increase in odor intensity occurred at lower concentrations.     

Adsorptive ozonation of 2-methylisoborneol in natural water with preventing bromate formation

This paper presents an application of our newly developed adsorptive ozonation process using a high silica zeolite adsorbent (USY) for drinking water treatment. First, the adsorption of 2-methylisoborneol (2-MIB) on USY in a river water/pure water mixture was clarified by a batch-type adsorption experiment. The results showed that 2-MIB was adsorbed on USY; however, almost all of the adsorbed 2-MIB was desorbed over time. The desorption rate was increased with the ratio of river water to pure water, indicating that compounds dissolved in the river water, such as natural organic matter (NOM), prevent the adsorption of 2-MIB on USY. Second, the ability of the river water to consume ozone was confirmed in an experiment using a USY-packed column reactor. The ozone consumption was obviously increased by the presence of USY, indicating that USY-adsorbing compounds dissolved in the river water (probably small size NOM) consumed the ozone. However, the rapid ozone consumption was occurred by 6-8 s in the retention times when 3.14-4.38 mgL(-1) of water dissolved ozone was fed, this rapid ozone consumption lasted no more than these times. This result revealed that the rapid consumption of ozone by the adsorptive compounds in our process could be avoided within a certain retention time (6-8 s; especially for the river water used in this study) when enough concentration of ozone (3.14 mgL(-1) or more; same above) was supplied. We therefore performed a trial in which 2-MIB dissolved in river water was continuously decomposed using a USY-packed column with various ozone concentrations. In the process, the adsorptive compound dissolved in the river water adsorbed and reacted with ozone in the parts of the apparatus upstream of the column, while the adsorption and decomposition of 2-MIB took place in the parts of the apparatus downstream of the column. This resulted in a sufficient 2-MIB decomposition with minimizing bromate ion formation.     

Origins and implications of drinking water odours in lakes and reservoirs of British Columbia, Canada

The relationship between commonly measured limnological parameters and odours was examined in 16 reservoirs and lakes used as sources for drinking water and three reference lakes. Odour analysis was conducted using flavour profile analysis (FPA) and, on select lakes, gas chromatography ion-trap mass spectrometry (GC-ITMS) for target compounds. Total phosphorus (TP) was the best single predictor of FPA intensity and multiple regression models accounted for 37-39% of intensity variance in the epilimnion and metalimnion, respectively. Earthy odours were more prevalent in reservoirs and lakes with higher TP, whereas decomposing vegetation and green vegetation+grassy odours almost exclusively occurred when TP was lower (<13 microg P/L). Only geosmin was identified with GC-ITMS, and it was found to occur in lakes and reservoirs of higher trophic status (e.g. more algal biomass). Infrequent episodic events in the Greater Victoria's principal reservoir (e.g. algal blooms) have previously been linked with taste and odour problems in their tap water. However, analysis of odours under the conditions of this study (i.e. no strong odour episodes in the source reservoir) suggest that typical odours prevalent in tap water originating from Sooke Lake Reservoir are derived from treatment processes or the distribution system, not directly from the reservoir. This study demonstrates the utility of employing relatively simple and established methods to better understand management issues of a drinking water system.     

Cryptosporidium spp. and Giardia duodenalis in two areas of Galicia (NW Spain)

The aim of the present study was to investigate the environmental dispersal of Cryptosporidium spp. and Giardia duodenalis in two distinct areas (coastal and inland) in Galicia (NW Spain). Faecal samples were collected from healthy asymptomatic domestic (cows and sheep) and wild animals (deer and wild boars) in the selected areas. In each of the selected areas, samples of untreated water (influent) and of treated water (final effluent) were collected from each of the 12 drinking water treatments plants (DWTPs) and 12 wastewater treatment plants (WTPs) under study. Analysis of a single sample from each of the 635 (coastal) and 851 (inland) domestic and wild animals selected at random revealed that the prevalences of cryptosporidiosis and giardiosis in coastal area were 9.2% and 15.9% respectively, and in inland area, 13.7% and 26.7% respectively. In the coastal area, Cryptosporidium spp. oocysts were detected in influent and effluent samples from 2/12 (16.6%) DWTPs and 8/12 (66.6%) WTPs, while G. duodenalis cysts were detected in influent and effluent samples from 3/12 (25.0%) DWTPs and 12/12 (100%) WTPs. The concentrations were notably higher in WTPs; the mean parasite concentrations in the final treated effluent were 10 oocysts per litre and 137.8 cysts per litre for Cryptosporidium and Giardia, respectively. The mean concentration of G. duodenalis cysts per litre was significantly higher (P < 0.05) than the mean concentration of Cryptosporidium spp. oocysts per litre in both the influent and the effluent samples from all the treatment plants. In the coastal area, C. parvum, C. hominis and G. duodenalis assemblages A (I and II) and E were most repeatedly detected. In the inland area, C. parvum, C. andersoni and G. duodenalis assemblages A (I and II), B and E were most frequently identified.     

Treated water quality assurance and description of distribution networks by multivariate chemometrics

Throughout the year 2007, 89 treated water samples from three water treatment plants (WTPs) of the Athens Water Supply and Sewerage Company (EYDAP S.A.) and 180 samples from network tanks (NWTs) were analyzed for electrical conductivity (EC), alkalinity (TA), pH, aluminium (Al), total hardness (TH), chloride (Cl⁻), residual chlorine (free Cl), calcium (Ca²⁺) and magnesium (Mg²⁺). The results regarding the WTPs were subjected to a principal component analysis (PCA) with 75% of the total variance being explained. A stepwise linear discriminant analysis (LDA) model constructed from the 89 treated water samples was used to predict class membership of the samples from the NWTs with a view to estimating the propagation of a possible water quality deterioration originating from the WTPs. The model utilized Cl⁻, Al and EC and yielded a 96% correct classification of the training dataset, whereas the cross-validation yielded a 94% correct classification. Network tank samples were 95% correctly classified with regard to their theoretically expected origin. The stepwise discriminant analysis based on separate covariance matrices of the canonical discriminant functions yielded a 98% correct classification of both the training dataset and the network tank samples. The classification and regression tree (C&RT) algorithm showed that the main parameters used in the discrimination of the WTP samples were EC and Al. The post-hoc classification of the training dataset was 99%, whereas 88% of NWT samples were correctly classified.     

固相微萃取/气质联用测定水中五种异味有机物

采用固相微萃取（SPME）法富集、气相色谱/质谱定量测定水体中的五种痕量异味有机物：2-异丙基-3-甲氧基吡嗪（IPMP）、2-异丁基-3-甲氧基吡嗪（IBMP）、2-甲基异冰片（2-MIB）、2,4,6-三氯苯甲醚（2,4,6-TCA）、土味素（Geosmin）.对五种物质的检出限均在5.0ng/L以下,加标回收率为86.7%～96.2%,相对标准偏差为3.9%～7.1%.     

应对高藻水源水的粉末活性炭吸附预处理研究

针对高藻期水源水存在的水质问题,结合其水质特点,利用小试和中试结合的方法研究应对高藻水源水的粉末活性炭吸附预处理技术,具体包括优选最佳的活性炭种类、确定相应的应用方案、分析其处理效能。研究结果表明,用于高藻期水源水处理的最佳粉末活性炭应该具有相对较发达的中孔和微孔,同时具有一定含量的含氧官能团;活性炭的投加量应在15 mg/L以上,并保证有30 min以上的接触时间,同时适当增加混凝剂的使用量,此时对微囊藻毒素、土臭素、2-MIB的去除率分别为90%、86%、93%,还可在一定程度上改善混凝沉淀单元对藻类的去除率,维持滤池的正常运行;使用粉末活性炭预处理时,应尽量避免与预氧化工艺组合使用,如果的确需要组合使用,两工艺应间隔适当的距离。