污水水质对消毒产生急性毒性的影响

利用发光细菌法考察了氯化／脱氯消毒过程中污水水质对消毒产生急性毒性的影响。研究发现，为准确客观地作出评价，首先应将不同加氯方式分开考虑；作为有毒副产物前体有机物的表征指标，UV254优于DOC，而DOC又优于COD；UV254值与有毒副产物前体物数量具有较好的相关性；在温度为20℃、消毒时间为30min、pH值为7．0的标准消毒条件下，当有效氯投量为10和50mg／L时，可以预测出峰点前加氯消毒后污水急性毒性增量(以Zn^2 浓度表示)。     

Br~-在水厂处理工艺中迁移转化及溴酸盐生成规律

对以东太湖水为水源的水厂处理工艺中溴酸盐的生成以及有机物的去除现状进行了研究。结果表明,溴离子在臭氧氧化过程中的主要产物为溴酸盐,但是加氯消毒会促进溴化物转化为含溴有机物;水厂处理工艺对水中DOC的去除效果一般,但对UV254的去除效果明显,且能够较好地控制工艺出水中的CODMn浓度。     

臭氧活性炭工艺对三卤甲烷前体物的去除性能研究

通过两组试验对水厂臭氧活性炭深度处理工艺去除三卤甲烷前体物的性能进行了研究。结果表明:…臭氧活性炭工艺能有效去除TOC和UV254;对三卤甲烷前体物去除效果显著,去除率达40%以上;臭氧氧化对三卤甲烷前体物去除能力较小,活性炭滤池过滤去除效果显著。经臭氧活性炭工艺处理的水加氯消毒后三氯甲烷生成量较处理前可减少50%以上。臭氧活性炭工艺能有效降低消毒生成三卤甲烷的风险。     

饮用水处理工艺中NDMA的生成与去除特性研究

对浙江某水厂各工艺单元出水中的二甲基亚硝胺(NDMA)浓度进行了检测,开展了氯化和氯胺消毒后NDMA生成潜能的研究,并探索了生成潜能与其他水质参数的相关性。结果表明,在预处理和常规处理工艺出水中未检出NDMA的条件下,经臭氧氧化后可生成NDMA,其浓度达到13.7 ng/L;后续的生物活性炭工艺可去除部分NDMA,经加氯消毒后出厂水的NDMA为11.6ng/L;氯胺化的NDMA生成量约为氯化生成量的3~5倍,即出厂水采用氯胺消毒产生NDMA的风险更大;经深度处理后氯化和氯胺化的NDMA生成潜能可分别削减14.1%和8.8%,其中生物预处理工艺可有效去除NDMA的前体物;NDMA生成潜能与DOC、UV254、DON值之间均存在较好的相关性,其中与DON的相关系数可分别达到0.97和0.91,因此有效控制有机氮类化合物,可降低NDMA的生成风险。     

不同分子质量区间腐殖酸的氯化反应特性研究

以自配的腐殖酸水样为研究对象,投加次氯酸钠对其进行消毒,考察了消毒过程中三卤甲烷、卤乙酸的生成量及DOC、UV254、A410、A465/A656的变化情况。结果表明,分子质量为50—100ku的腐殖酸为生成三卤甲烷和卤乙酸的最主要前体物;消毒反应后,各分子质量区间腐殖酸的DOC、UV254和A410都有不同程度的下降,且对小分子质量腐殖酸的DOC、UV254和A410的去除率高于对大分子质量腐殖酸的;A465／A656的变化表明消毒过程中腐殖酸的分子质量呈下降趋势。     

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。     

预臭氧化CT值对滦河原水有机物去除效果的影响研究

以天津市引滦原水为研究对象,研究了不同臭氧投加量(C)和不同反应时间(T)条件下预臭氧化工艺对DOC,UV254和SUVA等有机物指标的影响。结果表明,引滦原水经不同CT值条件下的预臭氧化处理后,随着初始臭氧浓度的增加和反应时间的延长,出水UV254和DOC值逐渐降低,SUVA值总体呈降低趋势。UV254去除率为9.1%~63.6%,DOC去除率仅为4.6%~34.9%。当初始臭氧质量浓度为2.024 mg/L,反应时间为10 min时,预臭氧化出水的UV254和SUVA值最低,当初始臭氧质量浓度为1.352 mg/L,反应时间为10 min时,预臭氧化出水的DOC值最低。     

南方某水厂臭氧/活性炭深度处理工艺运行效果

以南方地区微污染水源水为对象,研究臭氧/活性炭深度处理工艺对有机物综合指标UV(254)、COD(Mn)、TOC的去除效果以及对消毒副产物的控制效果,并结合三维荧光光谱技术分析溶解性有机物的荧光特性。结果表明,与常规处理工艺相比,增加臭氧/活性炭深度处理工艺后,对UV(254)、COD(Mn)、TOC、三卤甲烷前体物的去除率分别提高了47.05%、20.24%、31.11%、37.70%。三维荧光光谱分析结果表明,该地区微污染水源水主要由芳香性蛋白质类物质、溶解性微生物代谢产物类物质和富里酸类物质组成,臭氧/活性炭深度处理工艺对荧光溶解性有机物的去除效果明显。     

微污染北江源水的深度处理工艺优选

采用预氧化＋常规处理＋深度处理工艺对微污染北江源水进行了中试研究，考察了在预臭氧、预氯化和无预处理方式下，GAC和O3-BAC深度处理工艺的除污效果。结果表明：采用预臭氧氧化方式可大大改善常规处理工艺对CODMn、UV254的去除效果；在预臭氧氧化方式下，O3-BAC和GAC深度处理工艺均能在长时间内保持对有机物的高效去除，且前者的去除效果及其活性炭的使用周期均优于后者；活性炭吸附对氨氮无明显去除效果，而生物降解能较好地去除氨氮；预臭氧氧化能有效去除原水中的THMFP，但生成的CHCl3不能通过生物降解被去除，只能被活性炭所吸附，在活性炭吸附饱和后出水CHCl3浓度比进水的高；从长远角度考虑，对于北江源水，预臭氧＋常规处理＋O3-BAC是一种较优的组合工艺，它能够有效去除饮用水中的有毒、有害物质，并保障饮用水的安全性。     

预臭氧化工艺处理高藻水的应用研究

以滦河水为处理对象,对天津市泰达自来水厂预臭氧化—紫外/氯联合消毒工艺的运行效果进行分析.分别对各处理单元出水中的藻类、叶绿素a、pH值、浊度、DOC和UV254进行测定,结果表明:整个工艺运行平稳,出水水质较好.原水经过预臭氧化处理后,藻类数量和叶绿素a浓度均有降低,预臭氧化单元对藻类和叶绿素a的平均去除率分别为38.26％和36.25％;整个工艺对藻类和叶绿素a的平均去除率分别可达75.55％和99.01％.此外,预臭氧化对原水的pH值及去除浊度、UV254和DOC也有一定的影响.预臭氧化可有效降低浊度和UV254值,但对去除DOC的影响不明显.     

超滤膜处理净水厂沉淀池出水的中试研究

采用中试规模的内压式超滤膜系统处理水厂沉淀池出水,考察超滤膜系统长期运行的出水水质情况。结果表明,超滤膜系统在处理不同水质期沉淀池出水时具有较高的除浊率,平均除浊率达到93.4%,且99.4%的出水浊度<0.1 NTU,去除效果明显优于同期传统的滤池工艺。超滤膜系统对沉淀池出水中有机物的去除效果有限,对CODMn和UV254的平均去除率分别为17.2%和8.2%,出水CODMn≤2.0 mg/L的保证率在98%以上,膜出水CODMn浓度受进水水质和运行条件的影响不大。膜进水中以小分子质量有机物为主,在MW<1 ku区间内的DOC和UV254占到整体有机物含量的57.3%和53.5%。超滤膜系统对微生物的去除效果良好,膜出水水质大部分时间无需经过消毒就能保证卫生要求,可降低后续消毒的加氯量,从而减少消毒副产物的生成量。     

The effects of UV disinfection on drinking water quality in distribution systems

UV treatment is a cost-effective disinfection process for drinking water, but concerned to have negative effects on water quality in distribution system by changed DOM structure. In the study, the authors evaluated the effects of UV disinfection on the water quality in the distribution system by investigating structure of DOM, concentration of AOC, chlorine demand and DBP formation before and after UV disinfection process. Although UV treatment did not affect concentration of AOC and characteristics of DOM (e.g., DOC, UV_254, SUVA₂₅₄, the ratio of hydrophilic/hydrophobic fractions, and distribution of molecular weight) significantly, the increase of low molecular fraction was observed after UV treatment, in dry season. Chlorine demand and THMFP are also increased with chlorination of UV treated water. This implies that UV irradiation can cleave DOM, but molecular weights of broken DOM are not low enough to be used directly by microorganisms in distribution system. Nonetheless, modification of DOM structure can affect water quality of distribution system as it can increase chlorine demands and DBPs formation by post-chlorination.     

城市污水再生水氯消毒副产物比较研究

比较分析了对城市污水再生水采用液氯和二氧化氯消毒前后消毒副产物的变化。结果表明:城市污水再生水本身含有少量的氯代有机物,经液氯消毒后二氯甲烷、三氯甲烷含量大幅增加,为进水的3～4倍,同时产生了新的消毒副产物二氯一溴甲烷;经二氧化氯消毒后未出现新的消毒副产物,且原有副产物浓度基本不变。因此,再生水使用二氧化氯消毒具有明显优势。     

Measurement of dissolved organic nitrogen in a drinking water treatment plant: size fraction, fate, and relation to water quality parameters

This paper investigates the characteristics of dissolved organic nitrogen (DON) in raw water from the Huangpu River and also in water undergoing treatment in the full-scale Yangshupu drinking water treatment plant (YDWTP) in Shanghai, China. The average DON concentration of the raw water was 0.34 mg/L, which comprised a relatively small portion (~ 5%) of the mass of total dissolved nitrogen (TDN). The molecular weight (MW) distribution of dissolved organic matter (DOM) was divided into five groups: > 30, 10-30, 3-10, 1-3 and < 1 kDa using a series of ultrafiltration membranes. Dissolved organic carbon (DOC), UV absorbance at wavelength of 254 nm (UV254) and DON of each MW fraction were analyzed. DON showed a similar fraction distribution as DOC and UV254. The < 1 kDa fraction dominated the composition of DON, DOC and UV254 as well as the major N-nitrosodimethylamine formation potential (NDMAFP) in the raw water. However, this DON fraction cannot be effectively removed in the treatment line at the YDWTP including pre-ozonation, clarification and sand filtration processes. The results from linear regression analysis showed that DON is moderately correlated to DOC, UV254 and trihalomethane formation potential (FP), and strongly correlated to haloacetic acids FP and NDMAFP. Therefore, DON could serve as a surrogate parameter to evaluate the reactivity of DOM and disinfection by-products FP.     

二氧化氯、氯胺顺序投加联合消毒工艺的研究

以天津市某自来水厂的滤后水为研究对象,采用二氧化氯、氯胺顺序投加联合消毒工艺对其进行消毒处理。运用化学分析和生物学试验的方法,考察了经不同投量的组合消毒后消毒剂残余量的变化,以及联合工艺的消毒效果和持续消毒能力。试验结果表明,经不同投量组合的二氧化氯、氯胺顺序投加联合消毒后,出水中的细菌总数及总大肠菌群均达到《生活饮用水卫生标准》的要求。氯胺投量对总余氯和二氧化氯残余量的影响显著,而二氧化氯的投加量对其残余量的影响不大。二氧化氯、氯胺顺序投加联合消毒工艺在低投量组合下就能达到良好的消毒效果,且持续消毒能力强。     

从DOC、AOC的变化分析二氧化氯消毒工艺

考察了二氧化氯（CIO2）及其组合消毒工艺中溶解性有机物（DOC）浓度和可同化有机碳（AOC）浓度的变化规律。结果表明,以DOC表征的有机物浓度在消毒反应前后变化不大;CIO2的强氧化能力体现在将高分子有机物氧化成中、小分子有机物方面,氧化产物以草酸类物质为主,这导致了AOC浓度的升高,降低了出水的生物稳定性;增加CIO2的投量（〉4mg／L）或与氯胺组合消毒能有效降低出水的AOC浓度,消毒反应24h后出水的AOC浓度均比进水的（59μg/L）低。     

Fractionation of dissolved organic matter from surface waters using macroporous resins

To obtain fractions enriched with biodegradable dissolved organic carbon (BDOC) or with organic compounds responsible for the chlorine demand (CID) and for trihalomethane formation potential (THMFP), Seine river water samples were percolated on various macroporous resins (anionic, cationic and non-ionic) and compared with granulated activated carbon (GAC). In addition, measurement of UV absorbance at 254 nm and the fluorescence index (λ_excitation 320 nm) had allowed to follow up the retention of dissolved organic matter by the different adsorbants. In contrast to cationic and non-ionic resins, anionic resins confirm their excellent retention capacity of organic compounds responsible for UV 254 absorbance and fluorescence index. The relative values of BDOC/DOC ratio (mg-C/mg-C) are slightly increased in the effluents of anionic resins, indicating that they retain a little preferentially the refractory fraction instead of the biodegradable fraction. There is no significant difference between the ratio of CID/DOC (mg-Cl₂/mg-C) in influent and effluent of anionic resins. Cationic resin has a low capacity for retention of DOC, but they seem to retain significantly the organic compounds responsible for CID. The capability of anionic resins to retain THMFP is similar to that of GAC.     

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.     

给水管网中细菌总数快速预测模型的建立与应用

对选定实际给水管网的水质进行了长期监测,研究了水质与细菌总数的相关关系,分析确定了与细菌总数相关性较高且易于测定的水温、自由余氯、总余氯、浊度及UV254等5项指标.应用多元线性回归分析建立了实际给水管网中细菌总数的快速预测模型.经验证,该模型预测的准确度为64.55%,能够用于实际给水管网中细菌总数的快速预测,可为保障供水管网水质微生物学指标的安全提供快速、可靠的技术支持.     

Effects of UV 254 irradiation on residual chlorine and DBPs in chlorination of model organic-N precursors in swimming pools

Ultraviolet (UV) irradiation is commonly applied as a secondary disinfection process in chlorinated pools. UV-based systems have been reported to yield improvements in swimming pool water and air chemistry, but to date these observations have been largely anecdotal. The objectives of this investigation were to evaluate the effects of UV irradiation on chlorination of important organic-N precursors in swimming pools.Creatinine, L-arginine, L-histidine, glycine, and urea, which comprise the majority of the organic-N in human sweat and urine, were selected as precursors for use in conducting batch experiments to examine the time-course behavior of several DBPs and residual chlorine, with and without UV₂₅₄ irradiation. In addition, water samples from two natatoria were subjected to monochromatic UV irradiation at wavelengths of 222 nm and 254 nm to evaluate changes of liquid-phase chemistry. UV₂₅₄ irradiation promoted formation and/or decay of several chlorinated N-DBPs and also increased the rate of free chlorine consumption. UV exposure resulted in loss of inorganic chloramines (e.g., NCl₃) from solution. Dichloromethylamine (CH₃NCl₂) formation from creatinine was promoted by UV exposure, when free chlorine was present in solution; however, when free chlorine was depleted, CH₃NCl₂ photodecay was observed. Dichoroacetonitrile (CNCHCl₂) formation (from L-histidine and L-arginine) was promoted by UV₂₅₄ irradiation, as long as free chlorine was present in solution. Likewise, UV exposure was observed to amplify cyanogen chloride (CNCl) formation from chlorination of L-histidine, L-arginine, and glycine, up to the point of free chlorine depletion. The results from experiments involving UV irradiation of chlorinated swimming pool water were qualitatively consistent with the results of model experiments involving UV/chlorination of precursors in terms of the behavior of residual chlorine and DBPs measured in this study.The results indicate that UV₂₅₄ irradiation promotes several reactions that are involved in the formation and/or destruction of chlorinated N-DBPs in pool settings. Enhancement of DBP formation was consistent with a mechanism whereby a rate-limiting step in DBP formation was promoted by UV exposure. Promotion of these reactions also resulted in increases of free chlorine consumption rates.