Ascorbic acid reduction of active chlorine prior to determining Ames mutagenicity of chlorinated natural organic matter (NOM)

Many potable water disinfection byproducts (DBPs) that result from the reaction of natural organic matter (NOM) with oxidizing chlorine are known or suspected to be carcinogenic and mutagenic. The Ames assay is routinely used to assess an overall level of mutagenicity for all compounds in samples from potable water supplies or laboratory studies of DBP formation. Reduction of oxidizing disinfectants is required since these compounds can kill the bacteria or react with the agar, producing chlorinated byproducts. When mutagens are collected by passing potable water through adsorbing resins, active chlorine compounds react with the resin, producing undesirable mutagenic artifacts. The bioanalytical and chemoanalytical needs of drinking water DBP studies required a suitable reductant. Many of the candidate compounds failed to meet those needs, including 2,4-hexadienoic (sorbic) acid, 2,4-pentanedione (acetylacetone), 2-butenoic (crotonic) acid, 2-butenedioic (maleic and fumaric) acids and buten-2-ol (crotyl alcohol). Candidates were rejected if they (1) reacted too slowly with active chlorine, (2) formed mutagenic byproducts, or (3) interfered in the quantitation of known chlorination DBPs. L-Ascorbic acid reacts rapidly and stoichiometrically with active chlorine and has limited interactions with halogenated DBPs. In this work, we found no interference from L-ascorbic acid or its oxidation product (dehydroascorbic acid) in mutagenicity assays of chlorinated NOM using Salmonella typhimurium TA100, with or without metabolic activation (S9). This was demonstrated for both aqueous solutions of chlorinated NOM and concentrates derived from the involatile, ether-extractable chlorinated byproducts of those solutions.     

Chlorination in a wastewater treatment plant: acute toxicity effects of the effluent and of the recipient water body

This study investigates the impact of wastewater treatment plant (WWTP) effluent on the toxicity of the recipient water body and the effectiveness of the disinfection treatment applied (sodium hypochloride) to assure the compliance of both microbiological and toxicological emission limits. No toxicity was found in the majority of samples collected from the recipient river, upstream and downstream of the WWTP, using three different toxicity tests (Vibrio fischeri, Daphnia magna, and Pseudokirchneriella subcapitata). Only three samples presented toxic unit (TU) values with V. fischeri, and one presented TU with P. subcapitata. The influent toxicity ranged from slightly toxic to toxic (TU = 0.68–4.47) with V. fischeri, while only three samples presented TU values with the other tests. No toxicity was found in the absence of chlorination, while the mean toxicity was 3.42 ± 4.12 TU with chlorination in the effluent. Although no toxicity or very slight toxicity was found in the receiving water, its residual toxicity was higher than the US EPA Quality Standard in two samples. Escherichia coli concentration had a lower mean value in the chlorinated effluent: 13,993 ± 12,037 CFU/100 mL vs. 62,857 ± 80,526 CFU/100 mL for the not chlorinated effluent. This difference was shown to be significant (p < 0.05). E. coli in ten chlorinated samples was higher than the limit established by European and Italian Legislation. The mean highest trihalomethanes (THMs) value was found in the influent samples (2.79 ± 1.40 μg/L), while the mean highest disinfection by-products (DBPs) was found in the effluent samples (1.85 ± 2.25 μg/L). Significant correlations were found between toxicity, sodium hypochlorite, THMs, DBPs, E. coli, and residual chlorine. In conclusion, this study highlighted that the disinfection of wastewater effluents with sodium hypochlorite determines the increase of the toxicity, and sometimes is not enough to control the E. coli contamination.     

The role of GC-MS and LC-MS in the discovery of drinking water disinfection by-products

Gas chromatography-mass spectrometry (GC-MS) has played a pivotal role in the discovery of disinfection by-products (DBPs) in drinking water. DBPs are formed when disinfectants, such as chlorine, ozone, chlorine dioxide or chloramine, react with natural organic matter in the water. The first DBP known--chloroform--was identified by Rook in 1974 using GC-MS. Soon thereafter, chloroform and other trihalomethanes were found to be ubiquitous in chlorinated drinking water. In 1976, the National Cancer Institute published results linking chloroform to cancer in laboratory animals, and an important public health issue was born. Mass spectrometry and, specifically, GC-MS became the key tool used for measuring these DBPs in water and for discovering other DBPs that were formed. Over the last 25 years, hundreds of DBPs have been identified, mostly through the use of GC-MS, which has spawned additional health effects studies and regulations. Early on, GC with low resolution electron ionization (EI)-MS was used, together with confirmation with chemical standards, for identification work. Later, researchers utilized chemical ionization (CI)-MS to provide molecular weight information and high resolution El-MS to aid in the determination of empirical formulae for the molecular ions and fragments. More recently, liquid chromatography-mass spectrometry (LC-MS) with either electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) has been used to try to uncover highly polar DBPs that most experts believe have been missed by earlier GC-MS studies. Despite 25 years of research in the identification of new DBPs, new ones are being discovered every year, even for chlorine which has been the most extensively studied.     

离子色谱法测定环境水样阴离子处理方法的试验

本文研究了离子色谱法测定环境水样中阴离子时样品的一般处理方法。该方法以固体无水碳酸钠处理水样并以酚酞指示剂指示处理的终点,以邻苯二甲酸除去样品碱性干扰,以活性炭吸附水样中的有机物和酚酞指示剂。研究测试和监测实践的结果表明,该方法应用于环境监测简单可靠。     

Disinfection by-product formation potentials in wastewater effluents and their reductions in a wastewater treatment plant

Disinfection by-product formation potentials (DBPFPs) in wastewater effluents from eight wastewater treatment plants (WWTPs) were investigated. In addition, a WWTP with one primary effluent and two different biological treatment processes was selected for a comparative study. Formation potential tests were carried out to determine the levels of DBP precursors in wastewater. WWTPs that achieved better organic matter removal and nitrification tended to result in lower DBPFPs in effluents. For the WWTP with two processes, haloacetic acid, trihalomethane, and chloral hydrate precursors were predominant DBP precursors in the primary and secondary effluents. The percent reductions of haloacetonitrile and haloketone formation potentials averaged at 96% which was high in comparison to the reductions of other classes of DBPFPs. In addition, biological treatment changed the DBPFP speciation profile by lowering the HAAFP/THMFP ratio. The eight plant survey and the comparative analysis of the WWTP with two processes implied that besides nitrification, there may be other confounding factors impacting DBPFPs. Oxic and anoxic conditions, formation and degradation of soluble microbial products had impacts on the DBPFP reductions. This information can be used by water and wastewater professionals to better control wastewater-derived DBPs in downstream potable water supplies.     

Disinfection By-Products in Water Produced by Ozonation and Chlorination

Water produced by advanced treatment of a groundwater was evaluated to determine the amount of DBPs (Disinfection By-Products) including trihalomethanes (THMs). Both Gas Chromatography (GC) and Gas Chromatography/Mass Spectrometry (GS/MS) were adopted for detection and identification of DBPs such as trihalomethanes (THMs), halo-acetic acids (HAAs) and aldehydes. Two disinfection modes (ozonation followed by chlorination and chlorination alone) were compared to determine the DBPs generation. The mutagenitic acivity of ozonated water, chlorinated water after ozonation and potable water was assessed using the Ames test. Chloroform, dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were the main constituents of THMs and HAAs, respectively. THMs accounted for more than 85% of all DBPs measured, whereas haloacetic acids accounted for around 14%. Ozonation followed by chlorination proved to be better in terms of THMs and HAAs control. The combined system produced 28.3% less DBPs compared to chlorination alone. Ozonation was found capable of reducing mutagenic matter in the groundwater by 54.7%. The combined system also resulted in water with no mutagenicity.     

GC-MS identification of gaseous volatiles in wastewater

Gaseous volatiles from wastewater samples taken from a local sewage treatment plant were air-stripped and trapped onto Tenax GC. These volatiles were then thermally desorbed and subsequently analyzed using a gas chromatograph coupled to a mass spectrometer (GC-MS). The results show that saturated aliphatic and aromatic hydrocarbons were the most dominant compounds found in the sewage gaseous volatiles. Other compounds found were chlorinated hydrocarbons, organic acids, sulfides and phenols. A wide variety of gaseous volatiles were found in the raw wastewater, the primary clarifier effluent, the pre-aeration wastewater and the sludge samples. A comparison of the gas chromatograms for the pre- and post-aeration wastewater shows that many odorous gaseous volatiles were removed during the aeration process in the treatment plant.     

水中汞监测存在的问题与解决办法

利用中日合作 (JICA)项目资金 ,对测定地表水中汞存在的主要问题 ,如水样的保存和处理 ,水样的消解 ,测汞的冷原子吸收法和原子荧光法等进行了研究。通过对 33个环境监测站的样品考核 ,发现测定结果与标准值相比 ,偏高的数据达 75 %以上。提出了用 1%H2 SO4 和 0 1%K2 Cr2 O7保存水样最好 ;高锰酸钾 -过硫酸钾消解法适用于消解含有机物、悬浮物和组成复杂的废水样 ,高锰酸钾 -硫酸消解法适用于消解被有机物轻度污染的废水 ,溴酸钾 -溴化钾消解法适用于消解地表水和含较少有机物的生活污水及工业废水。研究表明 :尤以硫酸 -高锰酸钾 -过硫酸钾消解体系消解地表水和废水效果良好。对冷原子吸收法和原子荧光法中影响汞测定的因素 ,如空白值高、干扰物的消除、载气种类和流量、反应瓶体积和气液比以及反应时间等提出了详尽的解决方法     

Study of personal–indoor–ambient fine particulate matters among school communities in mixed urban–industrial environment in India

A sampling program was conducted to investigate the formation of disinfection by-products (DBPs) and dissolved organic carbon (DOC) at two advanced water treatment plants in Kaohsiung City, Taiwan. The results in this study can be used as a reference for the operational control of water treatment plants and the setting of regulations in Taiwan. Samples of drinking water were collected from two advanced water treatment plants from June 2007 to April 2008. Changes in the concentration of dissolved organic carbon, the trihalomethane formation potential, and the haloacetic acids formation potential were measured in raw water samples. Variations in the concentrations of trihalomethanes (THMs) and haloacetic acids (HAA₅) in finished drinking water were evaluated. The major species of HAA₅ were in the order of dichloroacetic acid and trichloroacetic acid and the THM was of trichloromethane. DOC was strongly related to DBPs in raw water. In this investigation, the removal efficiency of DBPs in Plant A (ultrafiltration/reverse osmosis system) exceeded that in Plant B (ozonation/biological activated carbon system). Both advanced water treatment plants greatly improved the quality of drinking water.     

High Resolution GC - MS Analysis of VOCs in Wastewater and Sludge

High resolution gas chromatography - mass spectrometry (GC-MS) has been widely used in the field of environmental sample analysis for volatile organic compounds (VOCs) (Gryder-Boutet, et al., 1988). Such a technique was applied to the analysis of VOCs at a local municipal wastewater treatment plant. The combination of purge and trap sample preparation and thermal desorption with cryofocusing technology, allows for the detection of a wide range of volatiles in wastewater and sludge samples. Results show that a large variety of organics present in samples are aliphatic and aromatic hydrocarbons. Their concentrations are in part per billion levels between 10 to 150 g/L. Others identified using this method are chlorinated hydrocarbons, sulfides and organic acids. By comparing the chromatograms of different wastewater and sludge samples collected from various treatment process units, it can be seen that most volatiles were removed or degraded after the aeration or digestion process. Information that provides an insight to the measurement of organic compounds in sludges is also discussed in this paper.     

Impact of Post-Methanation Distillery Effluent Irrigation on Groundwater Quality

Molasses-based distilleries generate large quantities of effluent, which is used for irrigation in many countries including India. The effluent is rich in organic and inorganic ions, which may leach down and pollute the groundwater. An on-farm experiment was conducted to assess the impact of long-term irrigation with post-methanation distillery effluent (PMDE) on nitrate, sulphate, chloride, sodium, potassium, and magnesium contents in the groundwater of two sites in northwest India. Electrical conductivity (EC), pH, total dissolved solids (TDS), sodium adsorption ratio (SAR) and colour were also determined to assess the chemical load in the groundwater. Nitrate content in the groundwater samples ranged from 16.95 mg L⁻¹ in the unamended fields to 59.81 mg L⁻¹ in the PMDE-amended fields during the 2-year study (2001–2002). Concentrations of TDS in water samples from tubewell of the amended field was higher by 40.4% over the tubewell water of the unamended field. Colour of the water samples of the amended fields was also darker than that of the unamended fields. The study indicated that the organic and inorganic ions added through the effluent could pose a serious threat to the groundwater quality if applied without proper monitoring.     

Occurrence of haloacetic acids (HAAs) and trihalomethanes (THMs) in drinking water of Taiwan

In this study, water samples were collected from 86 water treatment plants for analysis of haloacetic acids (HAAs) and trihalomethanes (THMs) from February to March, 2007 and from July to August, 2007. Both seasonal and geographical variations of disinfection by-products (DBPs) in drinking water of Taiwan were presented. The results showed that the five HAA concentrations (HAA5) were 1.0–38.9 μg/L in the winter and 0.2–46.7 μg/L in the summer; and the total THMs were ND-99.4 μg/L in the winter and ND-133.2 μg/L in the summer. For samples taken from the main Taiwan island, dichloroacetic acid (29.4–31.7%) and trichloroacetic acid (25.3–27.6%) were the two major HAA species, and trichloromethane was the major THM species (49.9–62.2%) in finished water. For water treatment plants located on the offshore islands outside of Taiwan, high bromide concentration was found in raw water, and higher percentage of brominated THMs and HAAs were formed in the overall formation. A statistically significant (P?<?0.005) logarithmic linear regression model was found to be useful to describe the correlations between TTHM and HAA5 or nine HAAs (HAA5?=?1.219 ×TTHM ^0.754, R ²?=?0.658; HAA9?=?1.824 ×TTHM ^0.735, R ²?=?0.678). No apparent difference was observed for DBPs concentrations between finished water and distribution samples in this study.     

水中消毒副产物的监测方法研究进展

含氯、含氧等杀菌类消毒剂在饮用水生产、废水排放、再生水利用等环节应用广泛,会与水中的前驱物通过取代、氧化还原、水解、加成等反应形成种类繁多的消毒副产物(DBPs).DBPs的靶标监测基于已知DBPs的特性如挥发性、半挥发性、不挥发性等,采取相应的前处理和仪器分析方法;非靶标鉴别可对大量未知的DBPs进行筛查.综述了三卤...     

Formation of organic by-products during chlorination of natural waters

Natural water from six sources in Mytilene, Greece, was chlorinated in order to identify and quantify some of the organic by-products formed. The compounds examined were trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, chloral hydrate and chloropicrin. The factors tested were time and chlorine dose. The presence of bromide ion in some of the waters studied resulted in significant changes in the by-product speciation, with enhanced brominated species formation. In addition, UV absorbance, measured at three wavelengths, led to correlation of organic matter content with the concentrations of by-products produced. The species formed, varying among different water sources, increased with increasing chlorine dose. Most of the species also increased with increasing contact time, although there were some exceptions due to hydrolysis reactions.     

Techniques and methods for the determination of haloacetic acids in potable water

Haloethanoic (haloacetic) acids (HAAs) are formed as disinfection byproducts (DBPs) during the chlorination of natural water to make it fit for consumption. Sundry analytical techniques have been applied in order to determine the concentrations of the HAAs in potable water supplies: gas chromatography (GC-MS, GC-ECD); capillary electrophoresis (CE); liquid chromatography (LC), including ion chromatography (IC); and electrospray ionization mass spectrometry (ESI-MS). Detection limits required to analyze potable water samples can be regularly achieved only by GC-ECD and ESI-MS. Without improvements in preconcentration or detector sensitivity, CE and LC will not find application to potable water supplies. The predominant GC-ECD methods use either diazomethane or acidified methanol to esterify (methylate) the carboxylic acid moiety. For HAA5 analytes, regulated under the EPA's Stage 1 DBP Rule, diazomethane is satisfactory. For HAA9 data gathered under the Information Collection Rule, acidified methanol outperforms diazomethane, which suffers from photo-promoted side reactions, especially for the brominated trihaloacetic acids. Although ESI-MS can meet sensitivity and selectivity requirements, limited instrumentation availability means this technique will not be widely used for the time being. However, ESI-MS can provide valuable confirmatory information when coupled with GC-ECD in a research setting.     

质谱及其联用技术在水中消毒副产物识别和分析中的应用

水中消毒副产物(DBPs)是在水消毒过程中消毒剂与水中溶解性有机物以及无机离子发生反应而产生,其对水环境生态安全和人体健康有不利影响。简述了DBPs的生成、种类、毒性和分析方法等,重点综述了气相色谱-质谱联用(GC-MS)、液相色谱-质谱联用(LC-MS)、离子色谱-质谱联用(IC-MS)以及超高分辨率质谱(UPMS)等质谱(MS)及其联用技术在水中DBPs识别和分析中的应用,分析了不同MS技术的特点和应用实例,提出了MS技术在DBPs研究领域的发展方向与挑战。     

Appropriate Preservation of Dairy Wastewater Samples for Environmental Analysis

Thousands of gallons of water are used in dairies to wash cows before milking and for cleaning equipment. The wastewater generated contains elevated levels of organic matter and pollutants, including nitrogen that once converted, may contaminate groundwater with nitrate. This study was conducted to determine the amount of sulfuric acid needed to preserve wastewater samples from a New Mexico dairy in the southwestern U.S. Titrations of wastewater from a local dairy using full strength (18 M) sulfuric acid were performed to determine the amount of acid needed to bring the pH of the sample to below two, the recommended pH for sample preservation. An average of 0.33 mL of acid was required for every 100 mL of wastewater. Due to sample variability, we recommend that 0.4 mL sulfuric acid be added for every 100 mL dairy wastewater sample to ensure adequate acidification. This quantity is twice the amount currently recommended in U.S. Environmental Protection Agency guidelines.     

Combining passive sampling and toxicity testing for evaluation of mixtures of polar organic chemicals in sewage treatment plant effluent

Effluent from sewage treatment plants has been associated with a range of pollutant effects. Depending on the influent composition and treatment processes the effluent may contain a myriad of different chemicals which makes monitoring very complex. In this study we aimed to monitor relatively polar organic pollutant mixtures using a combination of passive sampling techniques and a set of biochemistry based assays covering acute bacterial toxicity (Microtox), phytotoxicity (Max-I-PAM assay) and genotoxicity (umuC assay). The study showed that all of the assays were able to detect effects in the samples and allowed a comparison of the two plants as well as a comparison between the two sampling periods. Distinct improvements in water quality were observed in one of the plants as result of an upgrade to a UV disinfection system, which improved from 24x sample enrichment required to induce a 50% response in the Microtox assay to 84x, from 30x sample enrichment to induce a 50% reduction in photosynthetic yield to 125x, and the genotoxicity observed in the first sampling period was eliminated. Thus we propose that biochemical assay techniques in combination with time integrated passive sampling can substantially contribute to the monitoring of polar organic toxicants in STP effluents.     

On-line solid phase extraction and liquid chromatography/tandem mass spectrometry to quantify pharmaceuticals, pesticides and some metabolites in wastewaters, drinking, and surface waters

A simple on-line method was developed for the analysis of pharmaceuticals, pesticides and some metabolites in drinking, surface and wastewater samples. The technique is based on the use of on-line solid-phase extraction combined with liquid chromatography electrospray tandem mass spectrometry with positive electrospray ionization (LC-ESI(PI)-MS/MS). The injection of only 1 mL of filtered water sample is used with a total analysis time of 20 min, including the period required to flush the SPE cartridge with organic solvent and reconditioning the LC column. Method detection limits were in the range of 2 to 24 ng L(-1) for the compounds of interest, with recoveries from 87 to 110% in surface as well as wastewater samples. Matrix effects were observed for some compounds without exceeding more than 25%. All results displayed a good degree of reproducibility, with relative standard deviations (RSD) of less than 12% for all compounds. Moreover, at least 200 samples were analyzed without altering the performance of the pre-concentration column. This method was preferred over traditional off-line procedures because it minimizes tedious sample preparation, increases productivity and sample throughput. The analysis of various water and wastewater samples showed that caffeine, carbamazepine and atrazine could be detected in all the samples analysed and the selected compounds are always present in at least one of the sample types.     

环境中新型阻燃剂检测技术研究进展

新型阻燃剂(NFRs)是传统阻燃剂受到严格管控后的推广替代品,主要包括新型溴代阻燃剂(NBFRs)、新型氯代阻燃剂(NCFRs)和有机磷酸酯阻燃剂(OPFRs)等。NFRs是一类新污染物,大多属于持久性有机污染物。目前,已有多种NFRs在世界各地被检出,引起各国的普遍关注,环境中NFRs的来源及迁移转化规律也由此成为新的研究热点。通过综述环境样品中NFRs检测技术在提取、净化和仪器检测等方面的国内外研究现状,讨论了各种分析技术的特点,分析了NFRs分析过程的质量控制与质量保证问题,展望了该领域未来的发展趋势。