Identification of unknown disinfection byproducts in drinking water produced from Taihu Lake source water

Although disinfection byproducts(DBPs) in drinking water have been suggested as a cancer causing factor, the causative compounds have not yet been clarified. In this study, we used liquid chromatography quadrupole-time-of-flight spectrometry(LC-QTOF MS) to identify the unknown disinfection byproducts(DBPs) in drinking water produced from Taihu Lake source water, which is known as a convergence point for the anthropogenic pollutants discharged from intensive industrial activities in the surroundi...     

Occurrence of selected aliphatic amines in source water of major cities in China

The formation of toxic nitrogenous disinfection byproducts (N-DBPs), such as nitrosamines, halonitromethanes and haloacetonitriles, from reactions between chlorine/chloramine and dissolved organic nitrogen in drinking water has caused great concern with regarding public health. This study revealed the occurrence of 17 aliphatic amines, some of which have been confirmed to be the precursors of N-DBPs, in source water across China. A sensitive method based on benzenesulfonyl chloride derivatization and liquid-liquid extraction followed by GC-MS analysis was established for the simultaneous analysis of the selected amines in aqueous samples. In total, 37 source water samples from the capital cities of 20 provinces were collected for the survey. Among the 17 amines, 14 were detected with an average frequency of detection of 36%. The most relevant amines in terms of frequency and maximum concentrations detected were dimethylamine (100%, 24.82 μg/L), methylamine (78%, 0.92 μg/L), N-methylethylamine (70%, 8.84 μg/L), propylamine (59%, 10.69 μg/L), diethylamine (54%, 3.76 μg/L), N-methylbutylamine (35%, 3.07 μg/L), N-ethylpropylamine (35%, 0.52 μg/L), and piperidine (32%, 2.35 μg/L). This is the first large scale survey of the aliphatic amines occurrence in source water in the world. The wide presence of nitrosamine precursors like dimethylamine, N-methylethylamine and diethylamine, and the precursors of haloacetonitriles and halonitromethanes like methylamine and propylamine suggests that better source water management is required to ensure the safety of drinking water.     

Fatty acids and algal lipids as precursors of chlorination by-products

Six common algal fatty acids (FAs) with different numbers of double bonds, lipophilic fractions and proteins extracted from the diatom Navicula pelliculosa and algal cells were chlorinated to evaluate their potential in generating disinfection by-products (DBPs). The result showed that the more double bonds in the FAs, the higher the amounts of chloroform and dichloroacetic acid (DCAA) produced, but such a pattern was not observed for trichloroacetic acid (TCAA). Based on the previously reported composition of fatty acids in algal lipids, the DBP generation potentials of algal lipids were calculated. These predicted values were much lower than those measured in the chlorinated algal lipophilic fraction, suggesting unknown lipophilic fraction(s) served as potent DBPs precursors. Another calculation attempted to predict DBP production in algal cells based on algal lipid and protein composition, given quantified measured DBP production per unit algal lipid and proteins. The analysis showed that the observed DBP production was similar to that predicted (< 35% difference), suggesting that algal biochemical compositions may serve as a bioindicator for preliminary estimation of chloroform, DCAA and TCAA formation upon chlorinating algae.     

微生物对饮用水典型消毒副产物前体物的降解效能及其群落特征

相对于CF（氯仿）等C-DBPs（含碳消毒副产物）,DCAN（二氯乙腈）等N-DBPs（含氮消毒副产物）具有更高的毒性.控制DBPs（消毒副产物）的前体物是抑制DBPs产生的最有效方法之一.为考察微生物降解DBPs前体物对生成DBPs的影响,分别选取C-DBPs和N-DBPs的典型代表物CF和DCAN及其相应的典型前体物Tyr（酪氨酸）和Asp（天冬氨酸）为研究对象,采用微生物培养前体物的方式,探究微生物对典型前体物Tyr和Asp的降解效果及其对生成CF和DCAN的控制效果.结果表明:①Tyr和Asp两种前体物经微生物降解后,DOC（溶解性有机碳）的去除率分别为94.0%和85.6%,DON（溶解性有机氮）的去除率分别为69.0%和81.0%.②在前体物经微生物降解后的水样中,氯化或氯胺化消毒后生成CF和DCAN的量较降解前均大大减少.以Tyr为前体物,水样经微生物降解、氯化消毒后生成CF和DCAN的量分别降低了56.1%和89.5%,氯胺化消毒后生成CF的量降低了68.5%;以Asp为前体物,水样经微生物降解、氯化消毒后生成DCAN的量最高可降低99.9%,经微生物降解、氯胺化消毒后生成的CF可降低50.7%.③对水样中微生物菌群分析发现,在门水平上的菌群主要有变形菌门（Proteobacteria）、放线菌门（Actinobacteria）和拟杆菌门（Bacteroidetes）,在属水平上的菌属主要有伯克氏菌属（Burkholderia-paraburkholderia）、半角藻属（Haliangium）、分枝杆菌属（Mycobacterium）、沉积小杆菌属（Sediminibacterium）、norank_f_Chitinophagaceae和动胶菌属（Zoogloea）.研究显示,微生物降解对DBPs典型前体物Tyr和Asp的去除,以及对生成CF和DCAN的控制具有较大的潜力,变形菌和放线菌在降解DBPs前体物中起到了重要作用.      

ClO2消毒工艺对污水处理厂出水超级耐药基因的影响

为了研究二氧化氯（chlorine dioxide,ClO₂）消毒工艺对污水处理厂出水中超级耐药基因（super antibiotic resistance genes,SARGs）的去除效果,对污水处理厂出水消毒前后的水样进行了全年采集,并采用微孔滤膜正压过滤法及核酸吸附柱-洗脱法分别富集水中细菌和胞外核酸后,利用荧光定量PCR技术对其中的9种SARGs进行定量检测.结果表明,无论是胞内还是胞外核酸,均有NDM-1、MCR-1 和MEC-A被检测出;同时,ClO₂消毒后上述3种SARGs的胞内相对总浓度明显上升（P<0.05）,且ClO₂消毒对胞内SARGs相对浓度的影响与季节有关,其中春季、夏季和秋季均发生上升,且春季升高最为明显,达2倍,而冬季出水在消毒前后均未测出胞内SARGs;胞外SARGs则在ClO₂消毒前后没有明显浓度变化.因此,ClO₂消毒不能有效去除污水处理厂出水中胞内和胞外SARGs污染.     

城市污水再生处理工艺中发光细菌毒性变化的初步研究

保障再生水的生态安全是污水再生利用过程中非常关键的问题.本文采用发光细菌毒性测试方法测定了2个城市污水再生利用示范工程工艺流程中生物毒性的变化,尤其是可能生成有毒副产物的氯消毒过程中的毒性变化.结果表明,二级生物处理能显著降低污水的发光细菌毒性,但氯消毒显著提高了污水的毒性,并且脱氯后污水的毒性仍保持较高的水平,对生态安全造成了潜在威胁.同时,通过比较2种污水水质发现,DOC(溶解性有机碳含量)和UV254(254 nm处的紫外吸收值)较高的水样,消毒后的毒性较大,认为DOC和UV254可望作为预测污水消毒生态风险的水质指标,为污水消毒实践中确定安全合理的污水水质条件提供一定的依据.     

Removal effect on Mesocyclops leukarti and mutagenicity with chlorine dioxide

Introduction The eutrophication of surface water is a worldwide problem, which is increasing in significance (Ma and Liu, 2002). Mesocyclops leukarti, a kind of Cyclops, is a waterborne animal that excessively propagates in eutrophic reservoirs and fresh …     

微污染水源中的氨氮及其处理技术

目前,我国饮用水水源部分呈现微污染特征.根据中国环保总局颁布的<环境状况公报>的近年来数据,可知水体中污染物之一氨氮已不容忽视.文中介绍了水中氨氮的来源、存在形态以及对水质、水处理工艺和人体健康的影响.对比了国内外饮用水标准中对"三氮"的规定,同时建议我国饮用水标准中宜逐步规定饮用水氨氮浓度的限值.并对目前处理微污染水源水中氨氮的曝气法、折点加氯法、离子交换法及生物预处理法等作了讨论.     

顺序氯化对微生物、副产物和生物稳定性的综合控制

在中试规模试验中,研究了“短时游离氯后转氯胺的顺序氯化消毒工艺”对微生物、消毒副产物和生物稳定性指标的控制效果.该顺序氯化消毒工艺综合利用了游离氯消毒灭活微生物迅速彻底,氯胺消毒副产物生产量低的特点,通过氯化消毒技术的组合,安全经济地实现了消毒卫生学和消毒副产物指标的双重控制.该消毒工艺对细菌总数、异养菌平板计数、总大肠菌群指标的控制效果略好于传统游离氯消毒,对脊髓灰质炎病毒和大肠杆菌f2噬菌体的灭活效果与游离氯相同.相同原水条件下,顺序氯化消毒工艺比游离氯消毒工艺产生的三卤甲烷浓度减少35.8%～77.0%;卤乙酸减少36.6%～54.8%.消毒进水水质越差,顺序氯化消毒工艺在消毒副产物控制方面就越有优势.该工艺对生物稳定性指标的控制效果明显高于游离氯消毒.     

氯对紫外线灭活枯草芽孢杆菌的协同作用

以枯草芽孢杆菌为研究对象,研究了紫外线和氯单独及联合作用时的灭菌效果.结果表明,单独氯消毒时,对枯草芽孢杆菌的灭活效果很低,CT值为300(mg·min)/L时,灭活率仅为0.53个对数级;单独紫外线消毒对枯草芽孢杆菌有较好的灭活效果,紫外线剂量为40mJ/cm²时,对其有3.3个对数级的灭活效果.紫外线和氯联合消毒时,对枯草芽孢杆菌的灭活效果大大增强,当紫外线剂量为40mJ/cm²,氯的CT值为300(mg·min)/L时,对枯草芽孢杆菌的灭活率可达6.2个对数级,远高于二者单独作用效果之和.紫外线与氯的作用顺序对消毒效果有明显影响,以先紫外线照射后再加氯的效果最好.通过Berenbaum公式计算可知,紫外线与氯联合灭菌是一种协同作用,并且随着紫外线剂量及氯投量的增加,协同作用增强.