饮用水管网中不同源有机污染物简析

饮用水管网中的有机污染物种类繁多, 直接威胁人类健康。本文简述了给水管网中的4类有机污染物, 即原水中带入的有机污染物、管材释放的各种添加剂及其降解产物、管垢释放产物或管垢生物膜和管内水体微生物的代谢产物、消毒副产物。根据现有的研究发现, 这4类有机物中, 以含量较多的消毒副产物类研究最多, 其次是管材释放的各种有机污染物, 而含量较低、种类繁多、取样困难的管垢释放产物及生物膜、水体微生物的代谢产物的研究较少。由于给水管网中的有机污染物成分多样, 同时在管网这个特殊的水环境中, 还会发生迁移、转化等复杂的过程, 本文在综述分析以上不同来源的污染物类型的基础上, 提出今后的研究可在高毒痕量有机污染物的鉴别、生物膜中有机污染物的释放规律及其代谢产物的定性定量分析、有机污染物的迁移转化等方面展开。     

Formation and fate of haloacetic acids (HAAs) within the water treatment plant

Most research on the occurrence of chlorinated disinfection by-products (DBPs) in drinking water has focused on trihalomethane (THM) formation and evolution, in particular within distribution systems. In this research, we investigated the variability of the occurrence of haloacetic acids (HAAs) during the treatment process in two facilities where surface water is pre-chlorinated before being treated by conventional physico-chemical processes. The investigation focused on both seasonal and point-to-point fluctuations of HAAs. In both facilities, samples were collected weekly during 1 complete year at four points in order to generate robust data on HAAs and on complementary parameters. The results showed that the initial formation of HAAs was the highest and the most variable in the plant where levels of DBP precursor indicators and the pre-chlorination dose were both higher and more variable. Subsequent formation of HAAs from the pre-chlorination point until the settled water occurred due to remaining levels of residual chlorine and DBP precursors. However, HAA levels and in particular dichloroacetic acid (DCAA) (the preponderant HAA species in the waters under study) decreased dramatically during filtration, very probably because of biodegradation within the filter. The effect of filtration on DCAA fate was season-dependant, with the highest degradation in warm water periods and practically no variation during winter. Statistical modeling was applied to empirically identify the operational factors responsible for HAA formation and fate. Model performance to identify HAA variability in waters following pre-chlorination was much better than for water following filtration, which is due to the lack of information on mechanisms and conditions favoring DCAA degradation.     

光触媒在饮用水处理中的作用研究

目前，水源污染日益严重，同时，传统消毒剂Cl2将与水中的有机物合成大量的致癌或致诱变的副产物，对人们的身体健康带来了很大的危害。光催化氧化在去除饮用水中有机物污染物及消毒副产物方面具有突出优点，本文主要就其在饮用水处理中的研究进行综述，并提出了今后研究方向。     

Preliminary laboratory investigation of disinfection by-product precursor removal using an advanced oxidation process

Natural organic matter (NOM) is ubiquitous in surface and ground waters throughout the world. During drinking water treatment, the NOM that remains in treated water can react with chlorine to form disinfection by‐products. It has been shown that titanium dioxide photocatalysis can achieve over 96% reduction in ultraviolet (UV)₂₅₄ absorbing species such as hydrophobic NOM and over 81% reduction in dissolved organic carbon (DOC). However, an additional filtration stage is required to recover the suspended catalyst before it is suitable for municipal drinking water application. To overcome this problem, we have used immobilised catalysts prepared using chemical sol–gels, and their performance has been assessed during bench‐scale experiments. An immobilised catalyst enables in situ regeneration using UV light and subsequent reuse of the catalyst. In this research, titanium dioxide sol–gels have been used to coat substrates at a laboratory scale. Results showed that the various coatings prepared had different removal efficiencies for both DOC and UV₂₅₄ absorbance. Maximum removals were 1.336 g/m² and 89%, respectively.     

Effect of chlorination on the formation of odorous disinfection by-products

In order to explain some of the possible origins of an odor episode, which took place in a drinking water supply in the region of Paris (France), the chlorination reaction of some simple amino acids (valine, leucine and phenylalanine) was investigated. In addition to the commonly admitted intermediates and products of this reaction (monochloramines, aldehydes and nitriles), the formation of far less documented products was observed: N-chloroaldimines which proved to present particular properties. These products appeared to remain relatively stable in water, especially at low temperatures, and can be formed under disinfection conditions relevant to those of drinking water treatment (i.e. at high chlorination rates). N-chloroaldimines also present strong swimming pool odors with a floral background, with odor detection thresholds close to 1microgL(-1) and even less. These values were established with a laboratory-made protocol. These products appeared more odorous than the corresponding aldehydes, known for a long time as potent odor causing chemicals and which have previously been involved in some odor problems in the field of drinking water treatment. N-chloroaldimines are consequently products of interest for water treaters and are now suspected to be a source of off-flavor concerns among consumers. We have therefore developed an analytical method (gas chromatography coupled with mass spectrometry) to demonstrate the presence of some of these compounds in water at concentrations close to their odor detection thresholds. Considering the levels of amino acids that can be reached in water, this level of chloroaldimines concentration could be obtained under certain pollution conditions.     

2. Comparison of the disinfection by-product formation potentials between a wastewater effluent and surface waters

In this study, the chemical reactivity with chlorine as measured by disinfection by-product formation potential (DBPFP) is compared among samples of a wastewater effluent and surface waters. Water samples that had higher anthropogenic impacts were found to have higher overall DBPFP due primarily to higher dissolve organic carbon (DOC) concentrations. Effluent-derived organic matter (EfOM), however, was found to be less reactive with chlorine on a per DOC concentration basis. Yet, EfOM had higher proportions of brominated DBP, which may be associated with greater health risks. In this research, pyrolysis-GC/MS was used to establish relationship between structural features of DOC and DBPFP. We show that there is a critical set of pyrolysis fragments that separates the waters based on the degree of anthropogenic influence. Even though no single chemical marker was found to be indicative of the formation potentials of different classes of DBP, combinations of chemical fragments were found to be associated with the formation potentials of total trihalomethane (THM), brominated THM, total haloacetic acid (HAA), and brominated HAA for this set of samples. In contrast to previous work, the phenolic signature of these samples was negatively correlated to DBPFP, whereas strong relationships were found between DBPFP and the organic nitrogen and halogenated signatures.     

饮用水消毒副产物的去除途径及进展

饮用水使用氯消毒产生的副产物对人类健康带来了极大危害.介绍饮用水消毒副产物的形成原因及影响因素,并从选择优质水源、降低消毒副产物的前体物质、替换传统的消毒剂、去除已生成的消毒副产物4个方面论述了饮用水中消毒副产物的各种去除途径及进展.     

Anaerobic biodegradation of an organic by-products leachate by interaction with different mine tailings

Deinking by-products from paper recycling have been used as cover materials on acid-producing tailings. Due to residual cellulose, anaerobic degradation leads to the production of an organic-rich leachate, which may percolate through the tailings. This study aims at describing the influence of the tailings’ characteristics on the attenuation of organic matter in leachate and at discussing the degradation mechanisms. To this end, leachate was mixed with different types of tailings, including three unoxidized tailings with varying acid generation potentials and one tailing in three states of oxidation. Regularly, selected biochemical parameters were analyzed to access the evolution of organic components. The results show that when leachate from deinking by-products was placed in contact with tailings, phase and acid–base balance reactions took place in the beginning. Subsequently, oxidation–reduction reactions dominated the chemistry of the system. The type, the constituents, and the state of oxidation of the mine tailings condition the mechanisms of biodegradation of organic components. Methanogenesis was predominant in the control sample (pure organic leachate) but was absent in all leachate-tailings mixtures. No biodegradation was observed in the liquid phase for oxidized tailings and the organic concentration remained constant for unoxidized tailings, independently of the acid-generation potential. The biodegradation efficiency was optimal when the leachate was in contact with a mixture of oxidized and unoxidized tailings due to sulfate-reduction.     

黄淮产区酿酒微生态环境的探究与打造

北方地区由于自然条件限制,易出现酿酒微生物富集困难、窖泥老化等问题,进而影响浓香型白酒的产、质量.为缓解这一现象,从塑造酿酒车间小环境、打造窖池间环境和维护窖内窖泥良好状态、优化大曲微生物等多个方面进行探究并运用于实际生产中去,在原酒产量、质量上取得了一定的成效.     

Modeling dichloroacetic acid formation from the reaction of monochloramine with natural organic matter

A kinetic model was developed to predict dichloroacetic acid (DCAA) formation in chloraminated systems. Equations describing DCAA formation were incorporated into an established comprehensive monochloramine-natural organic matter (NOM) reaction model. DCAA formation was theorized to be proportional to the amount of NOM oxidized by monochloramine and described by a single dimensionless DCAA formation coefficient, theta(DCAA) (M(DCAA)/M(DOC(ox)). The applicability of the model to describe DCAA formation in the presence of six different NOM sources was evaluated. DCAA formation could be described by considering a single NOM source-specific value for theta(DCAA) over a wide range of experimental conditions (i.e., pH, NOM, free ammonia, and monochloramine concentrations). DCAA formation appears to be directly proportional to the amount of active chlorine (monochloramine and free chlorine) that reacted with the NOM under these experimental conditions. Values of theta(DCAA) for all six NOM sources, determined by nonlinear regression analysis, varied from 6.51 x 10(-3) to 1.15 x 10(-2) and were linearly correlated with specific ultraviolet absorbance at 280 nm (SUVA(280)). The ability to model monochloramine loss and DCAA formation in the presence of NOM provides insight into disinfection by-product (DBP) formation pathways under chloramination conditions. The subsequent model and correlations to SUVA has the potential to aid the water treatment industry as a tool in developing strategies that minimize DBP formation while maintaining the microbial integrity of the water distribution system.