饮用水源中天然有机物的去除

近年来研究表明,在氯化消毒的饮用水中发现了大量的氯仿类有机卤代物,并有实验证明这些有机卤代物对人体有不同程度的危害,而这些卤代物的形成是由于氯化消毒机与饮用水源中的天然有机物发生反应而产生的,为了减少饮用水中的氯仿类卤代物,降低其对人体危害,本文从饮用水源中天然有机物的去除角度进行说明与分析。     

二氧化氯消毒对饮用水中有机卤代物形成的影响

二氧化氯消毒对饮用水中有机卤代物形成的影响①饮用水液氯消毒产生的氯仿等有机卤代物对人体的危害已引起人们的普遍关注，各国学者和专家纷纷致力于饮用水安全氯化消毒技术的研究。美国环保局推荐ＣｌＯ２消毒做为控制水中三卤甲烷（ＴＨＭ）最适宜的措施，并将它列为取...     

二氧化氯在水处理中有广阔的应用前景

加氯消毒会产生三氯甲烷和其它多种卤代有机物，对人体造成危害。二氧化氯无论在消毒效果，氧化能力，三氯甲烷和有机卤代物的形成以及毒理学上，都是可行的扫的取代品。采取适当的措施，二氧化氯能保证安全生产。同时，在经济上也是可以随的。所以，二氧化氯在水处理中肯定会有广阔的应用前景。     

水氯化消毒出水中的卤代物问题

氯化消毒出水中普遍检测出了有机卤代物 ,氯化水样的 Ames致突变研究结果表明为致突变阳性 .八个自来水厂水样的微核试验表明 ,氯化消毒出水对小鼠微核的发生产生了诱导作用     

浅谈卤代烷灭火剂

●浅●卤代烷灭火剂●梁永健卤代烷是由卤素原子取代烷烃分子中部分或全部氢原子后得到的一类有机化合物的总称。甲烷和乙烷的一些卤代物具有优良的灭火特性，且保存温度范围广（－２０℃～５５℃），常用作灭火剂。种类和命名通常用作灭火剂的是甲烷或乙烷的卤代物，其分...     

典型有机氮化物对卤乙酸生成量和耗氯量的影响

以自来水厂的滤后水为处理对象,研究了甘氨酸、半胱氨酸、赖氨酸、亮氨酸、天门冬氨酸和甲胺等6种典型有机氮化物对饮用水消毒过程中卤乙酸生成量和耗氯量的影响。结果表明,有机氮化物的存在会强化消毒过程中卤乙酸的生成,且卤乙酸生成量的增值与有机氮化物的含量呈正相关,同时与有机氮化物的性质和水体的pH有关;有机氮化物的存在还会使耗氯量增加,增值与有机氮化物含量成正比。有机氮化物强化卤乙酸生成的原因可能是:耗氯量的升高使得水中天然有机物与氯反应而生成的卤乙酸量增加;有机氮化物自身在氯化过程中生成了卤乙酸。     

氯胺消毒过程中碘代三卤甲烷生成的影响因素

碘代消毒副产物的"三致"特性远高于氯代和溴代消毒副产物,是近年来饮用水领域颇受关注的一类新兴消毒副产物。以微污染原水为研究对象,系统研究了其在氯胺消毒条件下碘代三卤甲烷类消毒副产物生成的影响因素。研究发现,在原水中存在一定浓度碘离子的条件下,采用氯胺消毒可产生较高浓度的碘代三卤甲烷类消毒副产物,其中以三碘甲烷为主;碘代三卤甲烷的生成总量随着反应时间的增加而增加;碘代三卤甲烷的生成量和组成受氯胺投加量的影响较大,在氯胺投加量较低的情况下主要生成三碘甲烷和一溴二碘甲烷,在氯胺投加量较高的情况下生成一氯二碘甲烷、二氯一碘甲烷、一溴二碘甲烷和三碘甲烷四种碘代三卤甲烷;碘代三卤甲烷的生成总量以及三碘甲烷在总碘代三卤甲烷中的比例随着碘离子浓度的增加而提高;总体上,氯胺化过程中碘代三卤甲烷的生成总量随着pH值的升高而增加。     

强化混凝去除饮用水中消毒副产物前驱物（DBPFP）的应用

天然有机物（NOM）是水体产生色度和嗅味的主要原因。它可分为腐殖质和非腐殖质两部分，腐殖质包含土壤浸析和从植物分解产生的有机物质——腐殖酸和富里酸等，非腐殖质包括亲水酸类、蛋白质、氨基酸、糖类。NOM能产生对人体有害的消毒副产物（DBP）的形成，如三卤甲烷（THMs）和卤乙酸（HAAs）。因此，NOM的有效去除是控制饮用水中DBPFP的关键问题，     

新型胶结材料LQ—冷玛(王帝)脂

LQ型冷玛(王帝)脂是以沥青为基料,加入脂肪族卤代衍生物有机混合溶剂、填料而形成的新型冷施工胶结材料。该材料稳定性好,粘接力强,防水性能可靠,可用于防水卷材的胶结等。     

臭氧化阶段溴类物质生成及其对溴代副产物的影响

通过小试考察了含溴水在臭氧氧化阶段溴类物质的生成规律及Br-的分配情况,以及Br-初始浓度、臭氧投加量、pH值和氨氮含量对溴酸盐和其他溴类物质生成的影响,并针对溴代三卤甲烷生成势(THMFP-Br)、溴代卤乙酸生成势(HAAFP-Br),进一步分析了Br-分配对溴代消毒副产物生成的影响。结果表明,初始溴离子浓度较臭氧投加量对各类溴代副产物的生成量影响大。降低pH值可获得较好的控制BrO-3和降低消毒副产物生成势及其溴代程度的效果,但同时也造成臭氧氧化阶段有机溴化物生成量的增加。氨氮可使THMFP、HAAFP有一定程度的降低。     

Effect Of Irradiation And Free Radicals On Formation Of Trihalomethanes In Chlorinated Water

In order to understand the formation of trihalomethanes (THMs) in chlorinated water and to control the production of THMs more effectively, effects of irradiation and free radical on the formation of THMs were observed. It was found that humic acid (HA) solution contains a semi-quinone free radical, which variation trendency was relative to the production quantity of THMs directly. Irradiating the solutions containing THMs precursor before chlorination could promote the formation of THMs, which reached the highest point at 30 minutes, after then decreased with longer irradiation time in this experimental condition. Irradiating the chlorinated solution, the yield of THMs decreased slowly because of the destruction of chlorine. The production quantity of THMs was inversely proportional to the wavelength of light sources.     

Occupational exposure to trihalomethanes in indoor swimming pools

The study evaluated occupational exposure to trihalomethanes (THMs) in indoor swimming pools. Thirty-two subjects, representing the whole workforce employed in the five public indoor swimming pools in the city of Modena (Northern Italy) were enrolled. Both environmental and biological monitoring of THMs exposure were performed. Environmental concentrations of THMs in different areas inside the swimming pools (at the poolside, in the reception area and in the engine-room) were measured as external exposure index, while individual exposure of swimming pool employees was estimated by THMs concentration in alveolar air. The levels of THMs observed in swimming pool water ranged from 17.8 to 70.8 microg/l; the mean levels of THMs in ambient air were 25.6+/-24.5 microg/m3 in the engine room, 26.1+/-24.3 microg/m3 in the reception area and 58.0+/-22.1 microg/m3 at the poolside. Among THMs, only chloroform and bromodichloromethane were always measured in ambient air, while dibromochloromethane was detected in ambient air rarely and bromoform only once. Biological monitoring results showed a THMs mean value of 20.9+/-15.6 microg/m3. Statistically significant differences were observed according to the main job activity: in pool attendants, THMs alveolar air were approximately double those observed in employees working in other areas of the swimming pools (25.1+/-16.5 microg/m3 vs. 14.8+/-12.3 microg/m3, P < 0.01). THMs in alveolar air samples were significantly correlated with THMs concentrations in ambient air (r = 0.57; P < 0.001). Indoor swimming pool employees are exposed to THMs at ambient air levels higher than the general population. The different environmental exposure inside the swimming pool can induce a different internal dose in exposed workers. The correlation found between ambient and alveolar air samples confirms that breath analysis is a good biological index of occupational exposure to these substances at low environmental levels.     

Carbohydrates as trihalomethanes precursors. Influence of pH and the presence of Cl(-) and Br(-) on trihalomethane formation potential

Upon chlorination carbohydrates can give trihalomethanes (THMs). In the present work, we have studied the influence of pH, chloride or bromide concentration on the formation of THMs from carbohydrates. We have observed that THMs are not formed at acidic pH, while basic pH values only increase slightly the THM content, although the consumption of chlorine increases up to 100% with respect to pH 8. The presence of chloride in ppm increases the THM formation from carbohydrates without influence of the chlorine consumption. In the same manner, the presence of bromide ions in ppb also increases remarkably the THMs formed upon chlorination of saccharides. Even more, we have observed that at bromide concentrations below 100ppb, complete incorporation of bromide in THMs occurs. Overall, the results obtained show that saccharides widely present in natural waters can give rise to significant THM concentrations in the disinfection process by chlorine.     

不同净水工艺对含溴水体消毒副产物生成势的影响

以溴离子和有机物浓度不同的5个水厂原水和各工艺段出水为研究对象,考察了不同净水工艺对三卤甲烷(THMs)和卤乙酸(HAAs)这两类典型消毒副产物生成势和种类分布的影响。结果表明,仅采用常规处理工艺对THMs和HAAs生成势的控制效果不明显,而增设生物预处理和臭氧氧化预处理工艺能显著提高常规工艺对THMs和HAAs前体物的去除效果,臭氧/生物活性炭(O3/BAC)深度处理工艺能进一步去除THMs和HAAs的前体物。增设预处理和O3/BAC深度处理工艺,并采取砂滤池后置的净水工艺流程对THMs和HAAs生成势的控制效果最好。对于含溴水体,溴离子浓度越高,有机物中亲水性组分所占比例越高,经氯消毒后生成的溴代THMs和HAAs所占比例就越高。随着处理工艺流程的进行,THMs和HAAs的生成势逐渐降低,但是它们的溴结合因子逐渐增大,即毒性更大的溴代组分所占比例逐渐增大。     

强化常规工艺对三卤甲烷前体物的去除效果研究

分别通过小试和生产性试验研究了强化混凝和强化过滤对三卤甲烷前体物的去除效果。结果表明,强化混凝能有效提高三卤甲烷前体物的去除效果,两组试验去除率最高分别可提高至50.62%和44.75%;相对石英砂滤池,采用炭砂滤池和活性无烟煤滤池进行强化过滤可将三卤甲烷前体物的去除率提高10%~20%,强化过滤出水加氯消毒后三卤甲烷生成总量比石英砂滤池出水低30%~40%,强化过滤后三卤甲烷生成风险显著降低。     

Low trihalomethane formation in Korean drinking water

Organics in water have the potential to generate harmful disinfection by-products (DBPs) such as trihalomethanes (THMs) during the chlorination process. To clarify the regulatory implications of Korean THMs levels which appear to be significantly lower than those in the US where the Stage 1 and 2 D/DBPs rule has been promulgated, the characteristics of THMs formation were investigated on five major river waters in Korea. Water samples were taken from 12 water treatment plants on five major rivers that serve as drinking water sources for more than 90% of the Korean population. Trihalomethane formation potential (THMFP), total organic halide formation potential (TOXFP) and ultraviolet absorbance at 254 nm (UV(254)) were determined and compared with those from US data. A survey of existing data [J Korean Soc Water Qual; 16(4) 2000b 431-443] provided evidence that THMs levels in treated drinking water in Korea were one-third of those reported in the US. The lower THMs levels were mainly attributable to the differences in the level and THMFP of dissolved organic carbon (DOC). The DOC levels and the THMFP normalized to DOC were approximately 60% of those in the US. Results which combined could quantitatively account for the lower THMs levels (i.e. 0.6 x 0.6 approximately 1/3) in Korea. The observed Korean THMs levels were over-predicted by the THMs model () developed in the US. The level of THMFP was found to be similar if normalized for aromaticity as measured by UV(254). These findings suggest that: (i) the case for more stringent THMs control is not likely to be a high priority among issues of drinking water quality in Korea; and (ii) significant variation of THMFP level may exist over different geographic regions; hence (iii) independent THMs models should be developed to make accurate predictions for different regions.     

DPB formation in breakpoint chlorination of wastewater

The formation of trihalomethanes (THMs) and haloacetic acids (HAAs), two major disinfection by-products (DBPs), from the breakpoint chlorination of three diluted yet buffered (pH 7.0) wastewater effluents was studied. The concentrations and distributions of THMs and HAAs species varied among different effluents at different zones of the breakpoint curves. Nevertheless, some common trends were observed. The formation of chloro-only THMs and HAAs, after normalization with the carbon contents of the effluents, increased with increasing the specific UV absorbance (SUVA) of the effluents but the dependency is not valid for bromo- or bromochloro-DBPs. The formation of THMs and HAAs showed no significant inclination with increasing chlorine dosages up to the breakpoint, but increased sharply beyond the breakpoint dosing level. Bromine incorporations into THMs and HAAs increased with an increasing bromide to DOC molar ratio. In addition, the bromine incorporation was also found to be highly dependent on the chlorine dosage and the bromide to ammonia ratio. A longer reaction time increased the yields of THMs and HAAs and was found to favor the formation of dihalogenated HAAs. A two-stage correlation between the total THMs and the total HAAs was found for each wastewater effluent.     

Adsorption of trihalomethanes from water with carbon nanotubes

Commercial carbon nanotubes (CNTs) were purified by acid solution and were employed as adsorbents to study adsorption of trihalomethanes (THMs) from water. The properties of CNTs such as purity, structure and nature of the surface were greatly improved after acid treatment which made CNTs become more hydrophilic and suitable for adsorption of low molecular weight and relatively polar THM molecules. The adsorption of THMs onto CNTs fluctuates very little in the pH range 3-7, but decreases with pH value as pH exceeds 7. A comparative study between CNTs and powdered activated carbon (PAC) for adsorption of THMs from water was also conducted. The short time needed to reach equilibrium as well as the high adsorption capacity of CHCl3, which accounts for a significant portion of THMs in the chlorinated drinking water, suggests that CNTs possess highly potential applications for THMs removal from water.     

Electrochemical removal of bromide and reduction of THM formation potential in drinking water

Trihalomethanes (THMs), a by-product of the chlorination of natural waters containing dissolved organic carbon and bromide, are the focus of considerable public health concern and regulation due to their potential as a carcinogen by ingestion. This paper presents a promising new water treatment process that lowers the concentration of bromide in drinking water and thus, lowers the THM formation potential. Bromide is oxidized by electrolysis to bromine and then the bromine apparently volatilized. The electrolyzed water, when chlorinated, produces measurably lower amounts of THMs and proportionately fewer brominated THMs, which are of greater public health concern than the chlorinated THMs. Removing bromide should also reduce the formation of other disinfection by-products such as bromate and haloacetic acids.