矿泉水臭氧消毒中溴酸盐的形成与控制

为控制矿泉水中溴酸盐含量,采用改变臭氧浓度的方法,对添加溴离子的矿泉水、超纯水和自来水分别进行臭氧氧化5 min,观察臭氧氧化过程中臭氧、溴离子以及水质对溴酸盐生成的影响;同时利用向自来水中添加一定浓度溴离子的方法,研究CT值(Ozone Concentration×Contact Time,CT)对溴酸盐生成的影响。结果表明,随着臭氧浓度和溴离子浓度的增加,溴酸盐生成量增加。当臭氧质量浓度≥0.4 mg/L,添加相同浓度的溴离子时,矿泉水中生成的溴酸盐量大于自来水和超纯水中溴酸盐量。矿泉水不同,添加相同浓度的溴离子,生成的溴酸盐量也不同,但当臭氧质量浓度≥0.4 mg/L时,溴酸盐量均大于10μg/L。CT值增大导致溴酸盐生成量大幅增加。因此,可以通过降低臭氧浓度和溴离子浓度的方法,减少臭氧消毒中溴酸盐的生成量。     

活性炭的筛选及其吸附饮用水中低量溴化物的研究

本文通过研究星光K02活性炭、星光K04活性炭和太西活性炭等六种活性炭对饮用水中低量溴化物的吸附效率,筛选出了吸附效果最佳的太西活性炭。同时探讨了不同的活化方式、不同的吸附时间以及饮用水中不同的p H值对TAC(太西活性炭)吸附饮用水中低量溴化物(7.50μg/L)效率的影响。实验采用了蒸馏水浸泡和稀盐酸浸泡两种活化方式,用CO_2酸化的方式将饮用水中pH值分别调至6.00、7.00和7.68三个水平,在不同的时间点取样,用离子色谱仪检测其溴化物含量。不同条件下,TAC吸附溴化物效率不同。实验结果表明,用稀盐酸浸泡作为活化方式,同时将饮用水的p H值调至6.00,在实验开始后的两个小时内TAC吸附溴化物效果最佳,能达到85.35%,此时溴化物含量为1.10μg/L,即使在后续的臭氧灭菌阶段,溴离子全部被氧化成溴酸盐,溴酸盐的值会在5μg/L以内,远小于GB 5749-2006和GB 8537-2018中溴酸盐的规定限值(10μg/L),同时,TAC对饮用水中的常量元素钾钠钙镁、微量元素锶及偏硅酸等影响不大(小于10%)。因此,在实际生产中,可先将饮用水中p H值调至6.00,然后采用盐酸溶液预处理后的TAC对饮用水中低量溴离子进行去除。     

柱后衍生离子色谱法测定矿泉水中痕量溴酸盐

建立了在线酸化—柱后衍生—离子色谱法测定天然含气矿泉水中痕量溴酸盐的分析方法。利用酸性条件下溴酸盐与过量氢碘酸生成强紫外吸收的碘三离子的特征反应,选用氢氧化物选择性的高效高容量阴离子交换分离柱IonPac AS19,一步梯度淋洗,23 min之内快速准确地完成了含气天然矿泉水中痕量溴酸盐的检测。方法在0.1～100μg/L范围内具有良好的线性,相关系数为0.999 95,对溴酸盐的检出限约为0.03μg/L。方法灵敏度高,可重复性较好,适用于含气天然矿泉水中痕量溴酸盐的准确定量工作。     

含溴矿泉水生产过程中溴酸盐的生成及控制

臭氧消毒作为氯消毒的替代方法,已被越来越多地应用到饮用水等行业,而臭氧消毒副产物溴酸盐已被国际癌症研究机构定为2B级的潜在致癌物。通过试验论证了臭氧浓度、溴离子含量和pH对溴酸盐生成的影响。在实际生产中,可以通过降低臭氧浓度、溴离子含量和pH的方法来减少溴酸盐的生成。     

矿泉水中溴酸盐的形成与控制

<正>正常情况下,自然界的矿泉水中溴酸盐的含量几乎为零,但是因其富含矿物离子的原因,溴离子(Br-)却是普遍都含有。在使用臭氧对含有溴化物的矿泉水进行杀菌消毒时,溴化物容易与臭氧发生反应,被氧化成为溴酸盐,并以Br03-的形式存在于水中。由于国家饮用水标准对菌落数量的要求非常严格,不少饮用水厂家采用O3对其水产品开展杀菌消毒的工作以降低菌落数量,由此也就顺理成章     

高压脉冲电场杀菌技术降低水中溴酸盐含量的研究

目的：寻找能够替代臭氧杀菌的新技术,以降低水中溴酸盐含量。方法：采用高压脉冲电场(pusled electricfield,PEF)杀菌技术,用靛蓝二磺酸钠分光光度法测定臭氧浓度,用离子色谱法测定溴酸盐的浓度。结果：PEF对水中常见微生物至少达到了5.5 个对数级降低的杀灭效果;含有0.54mg/L 溴离子质量浓度的水中分别加1.769mg/L、4.728mg/L 的臭氧,产生了0.039mg/L 和0.045 mg/L 的溴酸盐,而用电场强度为30kV/cm的PEF处理含有0.54mg/L 溴离子质量浓度的水,未检测到溴酸盐的产生。     

采用离子色谱法 准确测定饮用水中溴酸盐含量

对于使用臭氧深度氧化的自来水厂来说,出水水质中的微量溴酸盐含量是生态环境保护部门的检查重点。本文即采用离子色谱法对饮用水中的溴酸盐含量进行检测。一、实验部分1.仪器与试剂。实验使用的离子色谱仪器来自于瑞士万通公司,型号为882;此外,还包括MetrosepuASupp4阴离子分离柱、全自动进样器、H-Ag柱前清洗柱、超纯水系统等。     

水中氟离子改性活性炭去除效果研究

采用不同浓度AlCl3对活性炭进行改性处理,通过改性活性炭对水中氟离子的去除效果,确定最佳AlCl3浓度;同时研究了活性炭类型、活性炭用量和吸附时间对水中氟离子去除效果的影响。结果表明,0.50 mol/L AlCl3改性后的活性炭吸附24 h可以使水中氟离子质量浓度由6.41 mg/L降至0.45 mg/L,氟离子去除率最大,因此0.50 mol/L为AlCl3改性最佳浓度。活性炭类型不同,改性后对水中氟离子去除效果不同。随着活性炭用量的增加和吸附时间的延长,水中氟离子去除率增大。氟离子质量浓度为14.14 mg/L的水,经0.8 g改性活性炭吸附9 h后,水中氟离子质量浓度小于1 mg/L。     

臭氧灭菌机理及消毒副产物溴酸盐控制技术研究进展

臭氧消毒作为氯消毒的替代方法,在饮用水处理中被越来越多地应用.臭氧灭菌作用是通过生物化学氧化反应实现的,灭菌性能试验表明,臭氧几乎对所有细菌、病毒、真菌及原虫、卵囊都具有明显的灭活效果.但是含有溴离子的水臭氧化过程中形成的消毒副产物溴酸盐,被国际癌症研究机构定为2B级潜在致癌物.臭氧氧化过程中溴酸盐的生成有臭氧氧化和臭氧/氢氧自由基氧化两种途径,控制溴酸盐可以从控制其形成和生成后去除两个方面进行.降低pH、添加氨气、氯-氨工艺和优化臭氧化条件是控制溴酸盐形成的方法,溴酸盐生成后则可以利用物理、化学和生物方法去除.因此要实现臭氧、致病菌与溴酸盐三者的平衡需进一步探讨臭氧灭菌机理及溴酸盐控制方法.     

离子色谱法测定包装饮用水中的溴酸盐

对包装饮用水中的溴酸盐含量的测定方法进行研究,在现行国标的基础上,优化了色谱测定条件,并进行了方法学考察。该方法在5.00~100μg/L范围内线性关系良好(r=0.999 8),方法检出限为0.031 8μg/L,回收率为99.9%~102.5%(加标浓度25.25,50.50和75.75μg/L),重复性(n=6)为0.35%。并对乐山地区超市包装饮用水进行随机抽样调查,试样测定值在1.55~6.91μg/L之间,按GB 19298—2014限量要求(0.01 mg/L),均无过量添加。离子色谱法测定包装饮用水中的溴酸盐具有操作简便,灵敏度、准确度高,分离效果好,重现性佳等特点,可有效满足检验检测部门对包装饮用水中溴酸盐的测定。     

矿泉水中铜绿假单胞菌及溴酸盐污染情况分析

了解国标《饮用天然矿泉水》(GB 8537-2008)实施前后矿泉水中铜绿假单胞菌(Pseudomonas aeruginosa)及溴酸盐污染情况,分析其污染原因,采用国标GB/T 8538-2008/54滤膜法和GB/T 5750.10-2006离子色谱法对样品中PA和溴酸盐进行分别检测。结果发现,在2008年1月至2009年9月期间,水源水和成品水中PA超标率分别为11.43%和35.42%,成品水中溴酸盐超标率为42.12%。在2009年10月至2010年9月期间,水源水和成品水PA超标率分别为30.30%和7.65%,成品水中溴酸盐超标率为18.10%。国标实施前后成品水PA污染主要原因分别在于加工过程的污染和水源水的污染。因此国标实施后矿泉水中仍存在PA和溴酸盐超标现象。     

Bromate Formation from Bromide Oxidation by the UV/Persulfate Process

Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the bromate formation increased with increasing persulfate dosage and bromide concentration. The bromate formation was initiated and primarily driven by sulfate radicals (SO(4)(?-)) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr(-)) as an intermediate and bromate as the final product. Under the test conditions, the rate of the first step driven by SO(4)(?-) is slower than that of the second step. Direct UV photolysis of HOBr/OBr(-) to form bromate and the photolysis of bromate are insignificant. The bromate formation was similar for pH 4-7 but decreased over 90% with increasing pH from 7 to above 9. Less bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine atoms, HOBr/OBr(-) and SO(4)(?-). The extent of bromate formation and degradation of micropollutants are nevertheless coupled processes unless intermediate bromine species are consumed by NOM in real water.     

黑龙江省瓶(桶)装饮用水中阴离子检测结果分析

目的了解和分析黑龙江省瓶(桶)装饮用水中阴离子检测结果。方法按照《食品安全国家监督抽检和风险监测计划》要求,对全省流通和生产加工环节的瓶(桶)装饮用水的水中阴离子进行检测分析。结果共抽检486批次样品,总合格率为96.5%。按照不合格率由高到低,依次为瓶装饮用水5.6%,纯净水1.96%,矿泉水1.67%;不合格项目为亚硝酸盐、溴酸盐和硝酸盐,不合格率分别为0.62%、3.9%、0.83%。结论黑龙江省生产和流通环节饮用水水中阴离子情况整体较好,但仍需加大监管监测力度,尤其是对瓶装饮用水需要进行重点监测,对于溴酸盐和硝酸盐2种离子也要进行重点监测。     

Preloading hydrous ferric oxide into granular activated carbon for arsenic removal

Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 degrees C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 degrees C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 degrees C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 degrees C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26 mg As/g when the influent contained 300 microg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal.     

Removal of bromate from drinking water using the ion exchange membrane bioreactor concept

Bromate is a disinfection byproduct with carcinogenic properties that has to be removed from drinking water to concentrations below 10 or 25 microg/L. This work evaluates the applicability of the ion exchange membrane bioreactor (IEMB) concept for the removal of bromate from drinking water, in situations where nitrate is also present in concentrations up to 3 orders of magnitude higher than bromate. The batch results obtained show that the biological reduction of bromate was slow and only occurring after the complete reduction of nitrate. The specific bromate reduction rates varied from 0.027 +/- 0.01 mg BrO3(-)/g(cell dry weight) x h to 0.090 mg BrO3(-)/ g(cell dry weight) x h for the studied concentrations. On the other hand, transport studies, using anion exchange membranes showed that Donnan dialysis could efficiently remove bromate from polluted waters. Therefore, the use of a dense, nonporous membrane in the IEMB system, isolates the water stream from the biological compartment, allowing for the uncoupling of the water production rate from the biological reduction rate. The IEMB system was used for the treatment of a polluted water stream containing 200 microg/L of BrO3(-) and 60 mg/L of NO3(-). The concentrations of both ions in the treated water were reduced below the recommended levels. No bromate accumulation was observed in the biocompartment of the IEMB, suggesting its complete reduction in the biofilm formed on the membrane surface contacting the biocompartment. Therefore, the IEMB has proven to be a technology able to solve specific problems associated with the removal of bromate from water streams, since it efficiently removes bromate from drinking water even in the presence of nitrate, a known competitor of bromate biological reduction, without secondary contamination of the treated water by cells or excess of carbon source.     

Bromate in chlorinated drinking waters: occurrence and implications for future regulation

Bromate is a contaminant of commercially produced solutions of sodium hypochlorite used for disinfection of drinking water. However, no methodical approach has been carried out in U.S. drinking waters to determine the impact of such contamination on drinking water quality. This study utilized a recently developed method for quantitation of bromate down to 0.05 microg/L to determine the concentration of bromate present in finished waters that had been chlorinated using hypochlorite. Forty treatment plants throughout the United States using hypochlorite in the disinfection step were selected and the levels of bromate in the water both prior to and following the addition of hypochlorite were measured. The levels of bromate in the hypochlorite feedstock were also measured and together with the dosage information provided by the plants and the amount of free chlorine in the feedstock, it was possible to calculate the theoretical level of bromate that would be imparted to the water. A mass balance was performed to compare the level of bromate in finished drinking water samples to that found in the corresponding hypochlorite solution used for treatment. Additional confirmation of the source of elevated bromate levels was provided by monitoring for an increase in the level of chlorate, a co-contaminant of hypochlorite, atthe same point in the treatment plant where bromate was elevated. This study showed that bromate in hypochlorite-treated finished waters varies across the United States based on the source of the chemical feedstock, which can add as much as 3 microg/L bromate into drinking water. Although this is within the current negotiated industry standard that allows up to 50% of the maximum contaminant level (MCL) for bromate in drinking water to be contributed by hypochlorite, it would be a challenge to meet a tighter standard. Given that distribution costs encourage utilities to purchase chemical feedstocks from local suppliers, utilities in certain regions of the United States may be put at a distinct disadvantage if future lower regulations on bromate levels in finished drinking water are put into place. Moreover, with these contaminant levels it would be almost impossible to lower the maximum permissible contribution to bromate in finished water from hypochlorite to 10% of the MCL, which is the norm for other treatment chemicals. Until this issue is resolved, it will be difficult to justify a lowering of the bromate MCL from its current level of 10 to 5 microg/L or lower.     

Impact of treatment processes on the removal of perfluoroalkyl acids from the drinking water production chain

The behavior of polyfluoralkyl acids (PFAAs) from intake (raw source water) to finished drinking water was assessed by taking samples from influent and effluent of the several treatment steps used in a drinking water production chain. These consisted of intake, coagulation, rapid sand filtration, dune passage, aeration, rapid sand filtration, ozonation, pellet softening, granular activated carbon (GAC) filtration, slow sand filtration, and finished drinking water. In the intake water taken from the Lek canal (a tributary of the river Rhine), the most abundant PFAA were PFBA (perfluorobutanoic acid), PFBS (perfluorobutane sulfonate), PFOS (perfluorooctane sulfonate), and PFOA (perfluorooctanoic acid). During treatment, longer chain PFAA such as PFNA (perfluorononanoic acid) and PFOS were readily removed by the GAC treatment step and their GAC effluent concentrations were reduced to levels below the limits of quantitation (LOQ) (0.23 and 0.24 ng/L for PFOS and PFNA, respectively). However, more hydrophilic shorter chain PFAA (especially PFBA and PFBS) were not removed by GAC and their concentrations remained constant through treatment. A decreasing removal capacity of the GAC was observed with increasing carbon loading and with decreasing carbon chain length of the PFAAs. This study shows that none of the treatment steps, including softening processes, are effective for PFAA removal, except for GAC filtration. GAC can effectively remove certain PFAA from the drinking water cycle.The enrichment of branched PFOS and PFOA isomers relative to non branched isomers during GAC filtration was observed during treatment. The finished water contained 26 and 19 ng/L of PFBA and PFBS. Other PFAAs were present in concentrations below 4.2 ng/L The concentrations of PFAA observed in finished waters are no reason for concern for human health as margins to existing guidelines are sufficiently large.     

Impact of natural organic matter on monochloramine reduction by granular activated carbon: the role of porosity and electrostatic surface properties

Steady-state monochloramine reduction in fixed-bed reactors (FBRs) was quantified on five types of granular activated carbon (GAC) using two background waters-one natural source water (LAW) containing 2.5-3.5 mg/L organic carbon and one synthetic organic-free water (NW). While more monochloramine was reduced at steady-state using NW compared to LAW for each GAC and empty-bed contact time studied, the differences in removal varied considerably among the GACs tested. Physical characterization of the GACs suggested that the degree of interference caused by natural organic matter (NOM) increased with increasing GAC surface area contained within pores greater than 2 nm in width. Acid/base and electrostatic properties of the GACs were not found to be significant in terms of NOM uptake, which indicated that size exclusion effects of the GAC pores overwhelmed the impact of the GAC surface chemistry. Therefore, selection of GAC to limit the impact of NOM on monochloramine reduction in FBRs should be based on pore size distribution alone, with the impact of NOM decreasing with decreasing mesoporosity and macroporosity.