两种预氧化对氯消毒糖精DBPs转化的影响

预氧化是饮用水净化的一种高级处理方法,其目标是减少有机物及其衍生污染,然而部分难降解有机物在氧化后转化为小分子物质,更易与氯发生反应,从而可能增加衍生消毒副产物（DBPs）的风险。以糖精（SAC）为模型前体物,通过模拟试验考察了净水工艺中臭氧及UV/H₂O₂预氧化对人工合成有机物在氯消毒过程中产生DBPs的影响,以及DBPs随供水时间的变化规律。结果表明,臭氧及UV/H₂O₂工艺可使抗氯氧化的SAC转化为易与氯反应的小分子有机物,产生更高含量的二氯乙酸（DCAA）、三氯乙酸（TCAA）、三氯甲烷（TCM）、二氯乙腈（DCAN）等DBPs,卤乙酸类DBPs含量升幅最大。DBPs的生成势（DBPFP）随着臭氧及UV/H₂O₂氧化时间的增加呈先增后减的趋势,在氧化接触15～20 min时DBPFP最大。采用氯消毒并连续2 d供水条件下,TCM、DCAA、TCAA和DCAN等DBPs的生成量随接触时间的延长而逐渐升高。臭氧与UV/H₂O     

饮用水氯消毒生成DBPs的影响因素及其控制工艺

阐述了饮用水消毒副产物(DBPs)产生的影响因素,分析了天然有机物(NOM)、温度、pH、接触时间、氯用量和余氯浓度等各种因素对产生DBPs种类和数量的影响,提出了控制DBPs应从去除其前体物NOM,改变消毒工艺或采用新的消毒剂以及去除已生成的DBPs三方面入手.     

不同饮用水处理工艺中消毒副产物的生成潜能

对取自饮用水处理过程中的水样分别进行氯消毒和氯胺消毒,分析不同饮用水处理工艺对7类18种消毒副产物(DBPs)生成潜能的影响,测定的DBPs包括含碳DBPs[三卤甲烷(THMs)、卤乙酸(HAAs)、卤代酮(HKs)、三氯乙醛(CH)]和含氮DBPs[卤乙腈(HANs)、三氯硝基甲烷(TCNM)、总亚硝胺(TONO)]。结果表明,混凝、沉淀和过滤工艺均能有效降低卤代DBPs的生成潜能,活性炭吸附反而会增大TONO的生成潜能。混凝和砂滤工艺对去除含碳DBPs前体物更有效,氧化处理工艺则更有利于含氮DBPs前体物的去除。细胞毒性主要来源于HANs和HAAs,且其变化趋势大致与HANs和HAAs生成潜能一致。水中Br~-浓度的增加会显著增大溴代DBPs的生成潜能,并使细胞毒性大幅升高。     

饮用水氯和氯胺消毒过程中卤乙酸生成势的比较

消毒是保证饮用水微生物安全的重要单元,但消毒过程中产生的消毒副产物也会威胁人体健康。以南方某水源水为研究对象,比较氯和氯胺消毒过程中卤乙酸的生成趋势及影响因素。结果表明,p H值、溴离子及天然有机物(NOM)均对卤乙酸的生成量有影响。与氯消毒相比,氯胺消毒除了能显著降低卤乙酸的生成量,还可以抑制溴代乙酸的生成;随着氯消毒或氯胺接触时间的增加,卤乙酸含量逐渐提高,主要卤乙酸为二氯乙酸(DCAA)、三氯乙酸(TCAA)和一溴二氯乙酸(BDCAA),各种卤乙酸含量均随着接触时间的增加而不断增多。氯化消毒24 h时,生成的卤乙酸总量为32.4μg/L,其中DCAA占卤乙酸总量的45.4%,TCAA占卤乙酸总量的21.2%,BDCAA占卤乙酸总量的24.1%;氯胺消毒24 h时的卤乙酸生成总量为3.8μg/L,DCAA占卤乙酸总量的72.0%,TCAA占卤乙酸总量的11.9%,一溴一氯乙酸(BCAA)的比例为16.0%。氯胺消毒时卤乙酸生成的种类和量均比氯化消毒时有显著降低;当p H值升高时,无论是氯化消毒还是氯胺消毒,卤乙酸生成总量均呈降低趋势;氯和氯胺消毒时,随着溴离子浓度的增加,卤乙酸总量均明显增加,溴结合因子(BIF)也随之提高,但与氯消毒相比,氯胺消毒的溴结合因子要低;对氯化消毒和氯胺消毒两种方式进行比较后发现,消毒过程中均是疏水性有机物生成的卤乙酸总量最多,其次是中性有机物,亲水性有机物生成的卤乙酸总量最少。     

臭氧催化氧化与BAC联用控制氯化消毒副产物

研究了臭氧催化氧化与生物活性炭联用技术对氯化消毒副产物（DBPs）的控制效能。结果表明：常规工艺出水中分子质量为2000u左右的疏水性有机物是氯化消毒副产物的主要前质，其占DOC与UV254的比例分别为70％和80％，并与UV254有良好的线性相关性，故可用UV254作为DBPs前质的替代指标。臭氧催化氧化与生物活性炭联用对DBPs前质的去除效果显著，其中臭氧催化氧化可有效去除三卤甲烷（THMs）前质中的疏水性有机物及部分亲水性有机物，并提高了DBPs前质的可生化性，是给水深度处理中控制THMs前质的主要工艺环节。臭氧催化氧化／生物活性炭对UV254的控制是减少DBPs生成的一条有效途径。     

磺胺甲口恶唑氯化消毒副产物生成势及影响因素研究

研究了东太湖水源水中典型抗生素磺胺甲口恶唑(SMX)氯化消毒副产物(DBPs)生成势及影响因素。结果表明:SMX经氯化反应后可生成三卤甲烷、卤乙腈、卤乙酸、卤乙醛、卤代丙酮等多种DBPs,且加氯量、反应时间、反应温度、pH值等因素均会影响其DBPs生成势。当溶液中存在溴离子时,SMX氯化生成的三卤甲烷、卤乙酸的组分及生成量有较大变化,且随着溴离子浓度的增大,一些氯代消毒副产物(Cl-DBPs)会转化为具有更高毒性的溴代消毒副产物(Br-DBPs)。     

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。     

O3/BAC对氯化消毒副产物的控制作用

采用臭氧化—生物活性炭(O3／BAC)深度处理工艺去除水中消毒副产物前质的试验结果表明，该工艺能够有效去除水中消毒副产物前质，可控制氯化消毒副产物的生成，其中主臭氧化对三卤甲烷前质和卤乙酸前质均具有很好的去除效果，生物活性炭对卤乙酸前质表现出较好的去除效果，但对三卤甲烷前质的去除效果有限；藻类、有机物等在滤层的累积使得砂滤池在同一工作周期中的不同阶段对水中三卤甲烷前质的去除效果有所不同，因而需要合理设置砂滤池的反冲洗周期。臭氧化—生物活性炭工艺充分发挥了臭氧化和生物活性炭两种技术的优点，并相互促进和补充，能够充分保障饮用水的安全性。     

氯化与氯胺消毒生成消毒副产物的对比研究

通过小试试验,对比研究利用氯化和氯胺消毒对生成消毒副产物的影响。结果表明,随着次氯酸钠投加量的增加,氯胺消毒和氯化消毒产生的三卤甲烷均呈现逐渐增长的趋势,氯胺消毒产生的三卤甲烷明显比氯化消毒低,可降低76.58%;受限于前体物,氯化消毒产生的三氯乙醛随次氯酸钠投加量增加没有明显的变化趋势,氯胺消毒则呈现逐渐增长的趋势,氯胺消毒产生的三氯乙醛明显低于氯化消毒,可降低83.41%。     

消毒副产物三氯甲烷与膀胱癌的关系

<正>氯化消毒(chlorination)是饮用水加工过程中使用最广泛的消毒方式。然而,氯化消毒过程中可产生对健康有害的物质一消毒副产物(disinfection byproducs,DBPs)。消毒副产物主要包括三卤甲烷(trihalomethanes,THMs)、卤代乙酸(haloacefic acids,HAAs)、卤代乙腈(haloaceton itriles,HAN)等。毒理学研究显示DBPs具有遗传毒性、致突变性、细胞毒性、生殖发育毒性和致癌性。膀胱癌是指发生在膀胱黏膜上的恶性肿瘤。是泌尿系统最常见的恶性肿瘤,也是全身十大常见肿瘤之一。有研究表明消化副产物的暴露与膀胱癌     

Disinfection byproduct formation in reverse-osmosis concentrated and lyophilized natural organic matter from a drinking water source

Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking water research has been limited because the selected NOM sources are atypical of most drinking water sources. The purpose of this research was to demonstrate that reconstituted NOM from a lyophilized reverse-osmosis (RO) concentrate of a typical drinking water source closely represents DBP formation in the original NOM. A preliminary experiment assessed DBP formation kinetics and yields in concentrated NOM, which demonstrated that chlorine decays faster in concentrate, in some cases leading to altered DBP speciation. Potential changes in NOM reactivity caused by lyophilization were evaluated by chlorination of lyophilized and reconstituted NOM, its parent RO concentrate, and the source water. Bromide lost during RO concentration was replaced by adding potassium bromide prior to chlorination. Although total measured DBP formation tended to decrease slightly and unidentified halogenated organic formation tended to increase slightly as a result of RO concentration, the changes associated with lyophilization were minor. In lyophilized NOM reconstituted back to source water TOC levels and then chlorinated, the concentrations of 19 of 21 measured DBPs, constituting 96% of the total identified DBP mass, were statistically indistinguishable from those in the chlorinated source water. Furthermore, the concentrations of 16 of 21 DBPs in lyophilized NOM reconstituted back to the RO concentrate TOC levels, constituting 86% DBP mass, were statistically indistinguishable from those in the RO concentrate. This study suggests that lyophilization can be used to preserve concentrated NOM without substantially altering the precursors to DBP formation.     

The formation of halogen-specific TOX from chlorination and chloramination of natural organic matter isolates

The formation of disinfection by-products (DBPs) is a public health concern. An important way to evaluate the presence of DBPs is in terms of the total organic halogen (TOX), which can be further specified into total organic chlorine (TOCl), bromine (TOBr), and iodine (TOI). The formation and distribution of halogen-specific TOX during chlorination and chloramination of natural organic matter (NOM) isolates in the presence of bromide and iodide ions were studied. As expected, chloramination produced significantly less TOX than chlorination. TOCl was the dominant species formed in both chlorination and chloramination. TOI was always produced in chloramination, but not in chlorination when high chlorine dose was used, due to the limited presence of HOI in chlorination as a result of the oxidation of iodide to iodate in the presence of excess chlorine. The formation of TOI during chloramination increased as the initial iodide ion concentration increased, with a maximum of ∼60% of the initial iodide ion becoming incorporated into NOM. Iodine incorporation in NOM was consistently higher than bromine incorporation, demonstrating that the competitive reactions between bromine and iodine species in chloramination favoured the formation of HOI and thus TOI, rather than TOBr. Correlations between the aromatic character of the NOM isolates (SUVA₂₅₄ and % aromatic C) and the concentrations of overall TOX and halogen-specific TOX in chloramination were observed. This indicates that the aromatic moieties in NOM, as indicated by SUVA₂₅₄ and % aromatic C, play an important role in the formation of overall TOX and halogen-specific TOX in chloramination. THMs comprised only a fraction of TOX, up to 7% in chloramination and up to 47% in chlorination. Although chloramine produces less TOX than chlorine, it formed proportionally more non-THM DBPs than chlorine. These non-THM DBPs are mostly unknown, corresponding to unknown health risks. Considering the higher potential for formation of iodinated DBPs and unknown DBPs associated with the use of chloramine, water utilities need to carefully balance the risks and benefits of using chloramine as an alternative disinfectant to chlorine in order to satisfy guideline values for THMs.     

The effects of combined ozonation and filtration on disinfection by-product formation

The effects of combined ozonation and membrane filtration on the removal of the natural organic matter (NOM) and the formation of disinfection by-products (DBPs) were investigated. Ozonation/filtration resulted in a reduction of up to 50% in the dissolved organic carbon (DOC) concentration. Furthermore, humic substances were converted to non-humic substances, with changes in the humic and non-humic substance concentrations of up to −50% and +20%, respectively. Ozonation/filtration resulted in the formation of partially oxidized compounds from NOM that were less reactive with chlorine, decreasing the concentration of simulated distribution system total trihalomethanes (SDS TTHMs) and simulated distribution system halo acetic acids (SDS HAAs) by up to 80% and 65%, respectively. Reducing the molecular weight cut-off (MWCO) of the membranes resulted in reductions in the concentrations of SDS TTHMs and SDS HAAs. Using a membrane with a 5 kD MWCO, the minimum gaseous ozone concentration required to bring about effective NOM degradation and meet regulatory requirements for chlorinated DBPs was 2.5 g/m³.     

Halonitromethane formation potentials in drinking waters

Halonitromethanes (HNMs) are highly cyto- and genotoxic nitrogenous disinfection by-products (DBPs) that have been detected in some water distribution systems. In this study, a systematic investigation was conducted to examine the formation potential of HNMs in drinking waters under different oxidation conditions. Formation potential tests of samples obtained from various drinking water sources showed that ozonation-chlorination produced the highest HNM yields followed by in the order of chlorination, ozonation-chloramination, and chloramination. Similar or higher HNM yields were observed in the treated waters (i.e., after conventional water treatment) than in the raw waters, indicating that hydrophilic natural organic matter (NOM) components that are not effectively removed by conventional treatment processes are likely the main precursors of HNMs. This was further confirmed by examining HNM formation potentials of NOM fractions obtained with resin fractionation. Hydrophilic NOM fractions (HPI) showed significantly higher HNM yields than hydrophobic (HPO) and transphilic (TPH) fractions. The correlation analysis of HNM formation potentials during ozonation-chlorination with various water quality parameters showed the best correlation between the HNM yields and the ratio of dissolved organic carbon to dissolved organic nitrogen concentrations in the water samples tested.     

蜂窝陶瓷催化臭氧氧化处理饮用水中试

在北京市某净水厂进行了臭氧催化氧化处理滤后水的中试，对各种操作条件下蜂窝陶瓷催化臭氧氧化／颗粒活性炭过滤工艺的净水效果进行了考察。结果表明，与臭氧单独氧化相比，臭氧催化氧化反应器中有较高的溶解性臭氧浓度，对天然有机物（NOM）及总有机物（TOC）的去除效果较好，三氯甲烷生成潜能（CHCl3FP）较低。臭氧催化氧化的后续活性炭滤柱上的生物量较多，出水TOC、UV254及CHCl3FP值也均低于臭氧单独氧化的后续活性炭滤柱出水。     

Characterization of algal organic matter and formation of DBPs from chlor(am)ination

The frequent occurrence of algal blooms in drinking water reservoirs causes problems to water supply, one of which is the release of algal organic matter in high concentrations to affect drinking water quality. Algal organic matter, including extracellular organic matter (EOM) and intracellular organic matter (IOM), was characterized. The formation of a variety of disinfection by-products (DBPs) in chlorination and chloramination of EOM, IOM and algal cells was evaluated. Natural organic matter (NOM) isolated from Suwannee River was also studied for comparison. EOM and IOM were rich in organic nitrogen, which consisted of high (over 10 kDa) and low (70–1000 Da) molecular weight (MW) organic matter, whilst the MW of organic carbon in EOM and IOM was relatively lower. IOM had a higher fraction of total organic nitrogen, with larger proportions of higher MW and more hydrophobic contents than did EOM. IOM also contained higher fractions of free amino acids but lower fractions of aliphatic amines than did EOM. During chlorination of EOM and IOM, organic chloramines were first formed and then became undetectable after 1 d. Chlorination of EOM and IOM produced more nitrogenous DBPs (N-DBPs) and haloaldehydes and less carbonaceous DBPs (C-DBPs) than did chlorination of NOM. Organic chloramines were found after 3-d chloramination of EOM and IOM. The amounts of N-DBPs and C-DBPs formed from chloramination of EOM or IOM were much less than that from NOM. EOM produced less DBPs (except for trichloronitromethane) than did IOM and algal cells in chlorination and chloramination.     

氯胺消毒工艺中一氯胺生成效率的影响规律

以上海市某自来水厂滤后水为研究对象,系统考察了氯胺消毒过程中氮源种类、氯氮比、pH值、反应时间、温度、G值和氯投加速率等因素对一氯胺浓度及消毒副产物(DBPs)生成量的影响。结果表明,氮源种类、Cl₂/N质量比和p H值为主要影响因素,其他为次要影响因素。与氯化铵、碳酸铵、醋酸铵和氨水这4种氮源相比,以硫酸铵为氮源可生成较高浓度的一氯胺;当pH值由6.0增大到9.0时,一氯胺浓度(以Cl₂计)由2.611 mg/L升高至4.256 mg/L;随着Cl₂/N质量比由2∶1逐渐增至8∶1,一氯胺浓度先升后降,并在5∶1时达到最大值3.831 mg/L。DBPs浓度随Cl₂/N质量比、反应时间、温度和氯投加速率的增加而升高,随G值的增大而降低;而随着pH值由6.0增加到9.0,DBPs浓度先降低后略有增加。自来水厂氯胺消毒工艺中一氯胺生成的最佳工艺条件如下:以硫酸铵为氮源,Cl₂/N质量比为(4∶1)~(5∶1),pH值为中性或碱性,反应时间为2 h,温度为25℃左右,G值为300 s-1,混匀慢速加氯。     

氯化消毒条件及污水水质对生成THMs、HAAs的影响

系统地研究了消毒务件和水质在城市污水氯化消毒过程中对生成三卤甲烷和卤乙酸的影响。结果表明，投氯量对三卤甲烷和卤乙酸生成量的影响最大，投氯量为40mg／L时的生成量分别约是投氯量为5mg／L时的30倍和70倍。三卤甲烷浓度随反应时间和温度无明显变化，而卤乙酸浓度在反应2h后达到峰值并在之后逐渐降低，且随温度的升高呈下降趋势。pH对两类副产物生成的影响几乎相反，近中性条件下的三卤甲烷生成量最多而卤乙酸生成量最少。水中氨氮浓度的增加会导致三卤甲烷生成量略有下降，而卤乙酸浓度却大幅上升。溴离子浓度升高将导致三卤甲烷和卤乙酸生成量显著增加，其中三氯甲烷浓度下降，三溴甲烷浓度显著上升，混合取代的三卤甲烷浓度先增加后减少。与此类似，二氯乙酸和三氯乙酸浓度随溴离子浓度的增加而减少，含溴卤乙酸浓度则有不同程度的增加。反应温度、反应时间、pH和氨氮对污水消毒副产物生成的影响与已报道的饮用水消毒中的作用规律存在显著差异，甚至截然相反，这为有针对性地选取消毒工艺参数提供了依据。     

Formation of carbonaceous and nitrogenous disinfection by-products from the chlorination of Microcystis aeruginosa

Formation of carbonaceous disinfection by-products (C-DBPs), including trihalomethanes (THMs), haloacetic acids (HAAs), haloketones (HKs), chloral hydrate (CH), and nitrogenous disinfection by-products (N-DBPs), including haloacetonitriles (HANs) and trichloronitromethane (TCNM) from chlorination of Microcystis aeruginosa, a blue-green algae, under different conditions was investigated. Factors evaluated include contact time, chlorine dosages, pH, temperature, ammonia concentrations and algae growth stages. Increased reaction time, chlorine dosage and temperature improved the formation of the relatively stable C-DBPs (e.g., THM, HAA, and CH) and TCNM. Formation of dichloroacetonitrile (DCAN) followed an increasing and then decreasing pattern with prolonged reaction time and increased chlorine dosages. pH affected DBP formation differently, with THM increasing, HKs decreasing, and other DBPs having maximum concentrations at certain pH values. The addition of ammonia significantly reduced the formation of most DBPs, but TCNM formation was not affected and 1,1-dichloropropanone (1,1-DCP) formation was higher with the addition of ammonia. Most DBPs increased as the growth period of algal cells increased. Chlorination of algal cells of higher organic nitrogen content generated higher concentrations of N-DBPs (e.g., HANs and TCNM) and CH, comparable DCAA concentration but much lower concentrations of other C-DBPs (e.g., THM, TCAA and HKs) than did natural organic matter (NOM).