Results Of Bromide And Bromate Monitoring At Several Water Treatment Plants

The ozonation of water is a widely used technology within the water industry. Recent toxicological studies have shown that high bromate ion intake induces a high incidence of tumors in rats. Bromate ion formation from oxidation of water containing bromide ion was examined at nine treatment plants and one pilot. We found bromate ion (> 2 μg/L) in drinking water containing bromide ion when treated with ozone at pH greater than 7.0, even in the presence of ammonia. Bromate ion formation increased with the applied ozone dose. But bromate ion must be considered also as a byproduct of commercial sodium hypochlorite solutions. Under commercial conditions, chlorine dioxide and granular activated carbon had no effects on bromate levels.     

Practical Studies of the Electrolysis and Volatilization of the Bromide from Drinking Water to Minimize Bromate Production by Ozonation

In four recently published articles, a process for the oxidation of bromide to bromine and the volatilization of bromine from drinking water sources was presented. This process was shown to be able to remove up to 35% percent of the bromide found naturally in the California State Water Project. Although bromide itself is quite harmless, it has been shown to react with commonly used disinfectants to produce compounds or disinfection by-products (DBPs) of suspected carcinogens. Bromide reacts with ozone to form bromate. This article presents two studies of pilot scale, flow-through electrolytic reactors that oxidize bromide to bromine and volatilize bromine at <pH 3.5, which occurs at the anode as a result of the oxidation of water. One reactor had 14 anodes that were 91 cm deep and the other had 13 anodes 1.2 cm deep. The bromide removal rates were studied at several different water flows and power settings for different bromide concentrations for both reactors. The results show removal of bromide is impacted by water flows and power settings for different bromide concentrations. Effluent from the deep reactor did show some reduction in bromate concentration as compared to control samples but the results were inconsistent. This appeared to be caused by significant differences in the ozone demand produced by different experimental conditions, difficulty determining the concentration of chlorine, and the use of hydrogen peroxide as a dechlorinating agent. Using the shallow reactor, these difficulties were overcome by developing a more consistent determining chlorine concentration, using much larger ozone doses to overwhelm the ozone demand, and by using ascorbic acid instead of hydrogen peroxide. With these changes, it could be shown that the electrolytic reactor not only lowered the concentration of bromide in the water but when ozonated, the amount of bromate formed was reduced in direct proportion to the amount of bromide removed for an equal dose of ozone.     

Threshold Levels for Bromate Formation In Drinking Water

Ozone is a sufficiently strong oxidant to cause the oxidation of bromide ion and formation of bromate ion. In this study, bromate ion formation in a wide variety of drinking water sources was analyzed, with bromate ion formed in all sources under drinking water treatment conditions. Threshold levels for pH, bromide ion concentration, and ozone dose were found to be source-specific. Two non-linear empirical models were developed to predict bromate ion formation; these models are easy to use and require only several water quality and treatment variables. The models were tested against several literature data and a good simulation was found in other bench-scale tests, whereas the model tended to under-predict bromate ion formation in pilot-scale and full-scale programs.     

Bromoform Formation in Ozonated Groundwater Containing Bromide and Humic Substances

The effect of bromide ion, organic carbon concentration (natural aquatic humic substances), pH, and solar irradiation on the formation of bromoform in ozonated groundwater has been studied. The studies were conducted on four unique samples of groundwater taken from different regions of the Biscayne Aquifer in southern Florida. All other conditions being equal, increases in bromide ion concentrations resulted in increases in CHBrg formation. In three of the four samples, CHBr₃ formation decreased as the pH level increased from 5 to 9. The fourth sample exhibited an opposite trend whereby the CHBr₃ concentration increased with increasing pH. Bromoform concentration increased with increased O₃ concentration over an ozone dosage range of 3.4 to 6.7 mg/L.     

Fundamental Aspects of Ozone Chemistry in Recirculating Cooling Water Systems — Data Evaluation Needs

Proposed uses of ozone for stand-alone cooling water treatment raise critical questions as to what happens chemically. These questions are of more significance to industrial cooling water systems, which typically have higher temperatures and cooling ranges than do comfort cooling systems. When applying ozone to cooling waters, it is very important for the user to understand many fundamental aspects of ozone chemistry. For example, when ozone is added at water pH levels often encountered in cooling waters (≥ 8), it decomposes to form hydroxyl free radicals, which are stronger oxidizing agents than molecular ozone itself, but of microsecond half-life, and therefore are poor disinfectants. The presence of bicarbonate alkalinity, hardness, naturally occurring organics, bromide ion, and effects of pH levels on water quality parameters and molecular ozone, have pronounced effects on chemical reactions which occur when ozone is added to cooling waters. The authors review the fundamental chemistries involved with ozone in water, discuss the effects of water constituents present or expected to be present in recycling cooling waters, relate these aspects to biocidal efficacy of ozone treatment, and explore possible mechanisms for scale and corrosion control in cooling systems by ozone.

Recommended data needs will be discussed, particularly because currently published studies do not contain these data. For example, one explanation for the fact that low levels of applied ozone provide effective biofouling control throughout a cooling tower system in one case but not another may reside in the concentration of bromide ion in the water being ozonized. With bromide ion present, ozone quickly produces hypobromous acid, which is a much more stable biocide than is molecular ozone.     

Formation of Bromate Ion Through a Radical Pathway in a Continuous Flow Reactor

The contribution of ozone and hydroxyl radical to the formation of bromate ion was investigated in a continuous flow reactor. Experiments were conducted under a wide range of ozone dose (0.7 ～ 3.8 mgL), pH (6.5 ～ 8.5), and t-butanol concentration (0 ～ 0.5 mM). The formation of bromate ion was found to depend on radical reaction pathway, because the amount of bromate ion formed increased with pH and decreased with t-butanol, a radical scavenger, even when dissolved ozone concentrations were almost the same. In fact, the amount of bromate ion formed was reduced by 90% in the presence of t-butanol. Furthermore, the formation of bromate ion occurred even when dissolved ozone was not significantly detected in the presence of organic matter (TOC of 1 mgCL). The second-order reaction rate constant of hydroxyl radical with bromide ion, k _HO,Br^? of 1.7 × 10⁹ (M^?1s^?1), was obtained on the assumption that the reactions of bromide ion and t-butanol with hydroxyl radical were competitive with each other in the presence of t-butanol and that the formation of bromate ion depended on the reaction of bromide ion with hydroxyl radical. Therefore, it is concluded that the reaction of bromide ion with hydroxyl radical dominated in the overall reaction from bromide ion to bromate ion in the continuous flow reactor.     

Parameters Affecting the Formation of Bromate Ion During Ozonation

Batch type ozone experiments conducted on aquatic humic substances solutions spiked with bromide ion were developed to evaluate the importance of various parameters that may affect the formation of bromate ion during ozonation. The nature of the NOM, the alkalinity, the bromide ion content and the presence of ammonia were found to significantly affect the bromate ion production. Temperature and pH can be considered as minor factors. The ozonation of a clarified surface water using a continuous flow ozone contactor have shown that the addition of a low quantity of ammonia (0.05 to 0.1 mg/L NNH₄ ⁺) appeared to be an interesting option for controlling the bromate formation. On the contrary, the addition of hydrogen peroxide may enhance or reduce the bromate ion production, depending on the applied hydrogen peroxide/ozone ratio.     

Bromate Formation during Ozonation of Bromide Containing Drinking Water- a Pilot Scale Study

The effect of bromide ion concentration, pH, temperature, alkalinity, and hydrogen peroxide content on bromate formation was studied. Increase in pH was found to give the greatest increase in bromate formation. Also increase in the ozonation temperature, bromide ion concentration and hydrogen peroxide content increased the observed bromate concentration. Only increased alkalinity decreased the bromate formation during the ozonation experiments. Bromate formation exceeded the EU limit value for bromate ion, 10 μg/l, when the initial bromide ion concentration was around 100 μg/l, except for the alkalinity of 1.4 mmol/1, when the bromate formation was 9.4 μg/l.     

Compromise Between Bromate Ion Formation and Pesticides Degradation and/or Manganese Removal

Ozonation is a widely used technology within the water industry. Bromate ion formed by oxidation of water containing bromide ion was studied with the Gas Ozone Test and Pilot Scale Ozonation. Bromate ion formation was investigated along with the removal of triazines and/or manganese. Under identical conditions of ozonation, BrO₃ ^? formation is specific for each water and depends on parameters such as Total Organic Carbon, UV absorbance at 254 nm, applied ozone and ozone residual. Pesticides degradation by ozonation alone cannot be achieved without the formation of BrO₃ ^? at a high concentration. Hydrogen peroxide, at a constant ozone dose, reduces the BrO₃ ^? formation. However, even with the use of hydrogen peroxide, the concentration of BrO₃ ^? can remain in excess of the provisional Maximum Contaminant Level (10 μg/L). For certain types of water, pesticide degradation is difficult to achieve if the MCL for BrO₃ ^? has to be met. Manganese oxidation by ozone appears to be achieved without high bromate formation; indeed the presence of manganese hinders BrO₃ ^? formation.     

含溴废液中溴离子测定方法的研究

文章对含溴废液中溴离子含量的测定方法次氯酸钠-碘量法进行了探讨,采用平行测定,加标回收等方法,考察了该方法的实用性。试验结果表明,采用次氯酸钠-碘量法对含溴废液加标回收率为98.1%~101.7%,符合容量法回收率在95%~105%的要求,可用于含溴废液中溴离子浓度的测定。     

The Effect of Bromide Ion on the Formation of Organohalogen Disinfection By-products During Ozonation

Ozonation of water containing bromide ion (Br^?) leads to the formation of brominated disinfection byproducts (DBPs). The purpose of this study was to examine the influence of bromide ion upon the distribution and variation of organohalogen DBPs. Bromide ion concentration had a negative effect on chloroform formation as opposed to increased formation of brominated trihalomethanes (THMs). The results of factor analysis lead clearly to the interpretation that the bromide ion was strongly correlated with brominated THMs and less strongly with brominated HANs (haloacetonitriles). Compared to THMs and HANs, brominated HAAs (haloacetic acids) demonstrated a relatively weak correlation to bromide ion concentration. The addition of alkalinity enhanced the formation of chloroform when ozonation time was 10 to 30 minutes, while concentrations of other bromide ion-containing THMs decreased with increasing alkalinity.     

Empirically and Theoretically–Based Models for Predicting Brominated Ozonated By–Products

During water treatment, ozonation of waters containing bromide ion producesboth organic and inorganic disinfection byproducts. Bromide ion concentrations in U.S. waters range from 0.01 to 2 mg/L (Krasner, 1989). Bromoformand dibromoacetic acid (DBAA) are the major organic byproducts and bromateion is the major inorganic byproduct derived from ozonation. Bromoform is a known carcinogen and the existence of bromate ion in water supplies also is of public health concern (Lykins, 1986). Bromate ion causes renal failure and hearing loss in laboratory animals and in human beings (Kruithof, 1992). The provisional guideline for bromate ion as proposed by the World Health Organization is 25 pg/L and may be exceeded in water treatment processesusing ozone. Also draft drinking water regulations in the U.S. will specify a maximum contaminant level (MCL) of 10 µg/L for bromate ion and a bestavailable treatment (BAT) of pH adjustment.     

Enhanced Performance of Zn/Br Flow Battery Using N-Methyl-N-Propylmorpholinium Bromide as Complexing Agent

Redox flow batteries (RFB) are one of the most interesting technologies in the field of energy storage, since they allow the decoupling of power and capacity. Zinc–bromine flow batteries (ZBFB) are a type of hybrid RFB, as the capacity depends on the effective area of the negative electrode (anode), on which metallic zinc is deposited during the charging process. Gaseous bromine is generated at the positive electrode (cathode) during the charging process, so the use of bromine complexing agents (BCA) is very important. These BCAs are quaternary amines capable of complexation with bromine and generating an organic phase, immiscible with the aqueous electrolyte. One of the most commonly used BCAs in RFB technology is 4-methylethylmorpholinium bromide (MEM-Br). In this work, an alternative quaternary amine 4-methylpropylmorpholinium bromide (MPM-Br) was studied. MPM-Br was integrated into the electrolyte, and 200 charge–discharge cycles were performed on the resulting ZBFBs. The obtained results were compared with those when MEM-Br was used, and it was observed that the electrolyte with MPM-Br displays a higher resistance in voltage and higher energy efficiency, making it a promising alternative to MEM-Br.     

Determination of Chloride Content in Compounds and in Solutions of High Bromide to Chloride Concentration Ratios

A method is described for the determination of chloride in compounds and in solutions of high bromide to chloride molar ratios (up to 6300:1). Solutions were boiled briefly with nitric acid to oxidize the bulk concentration of bromide ion to bromine gas which was then flushed with air. Chloride ion was titrated potentiometrically with silver nitrate in 80% i-propanol-water medium using a silver-silver bromide indicator electrode and a chloride-free reference electrode. Details of the potentiometric techniques peculiar to these titrations are described. The method was successfully applied to the determination of the chloride content of commercially available bromide reagents.     

The Hydrozon-Kompakt Process-A New Method for Treatment and Disinfection of Swimming Pool and Bathing Water

The Hydrozon (R) Kompakt process (ozonation – sand filtration – bromination) relies on bromine (hypobromous acid/hypobromite ion) as the residual disinfectant in swimming pool and bathing water. As it performs its disinfection work, bromide ion is formed. Pool exit water is ozonized, not only to oxidize bather-added contaminants, but also to oxidize bromide ion back to hypobromous acid/hypobromite ions. Consequently, bromine is recycled in the pool water. However, the original process forms brominated hydrocarbons (brominated trihalomethanes), particularly bromoform, in excess of current German drinking water standards for total THMs (25 ug/L).     

溴甲烷及其替代产品

溴甲烷是一种高效、广谱熏蒸剂，用于土壤可有效防治真菌、细菌、病毒、昆虫、螨类、线虫、啮齿动物和杂革。溴甲烷也广泛用于耐久储存品、易腐烂商品及建筑物的熏蒸，在装运前的熏蒸也发挥重要的作用。但是溴甲烷是一种消耗臭氧层的物质，将逐步淘汰。介绍了溴甲烷的基本情况及其替代品应用进展。     

Ozone Swimming Pool Water Treatment Under Tropical Conditions

This paper presents the first year operation report of an ozone swimming pool water treatment system under the severe conditions of tropical climate. The system installed in a 70 m³ pool with upflow hydraulics, comprises sand filtration and ozone/bromide ion treatment. Cupric sulfate was chosen as algaecide and pH was kept between 7.5 and 7.8 by adding adequate amounts of HC1. When required, a slight flocculation (aluminum sulfate, 5 mg/L) was applied weekly. Water physicochemical analyses performed twice a week throughout the year, including microbiological tests, clearly demonstrated the remarkable efficiency of the treatment, fulfilling all water quality standards, even at high bather loads and during the summer months (at water temperature higher than 31[ddot]C and an intense sunlight) being economically feasible as well. This experience will allow the extension of ozone water treatment to larger swimming pools in similar circumstances.     

A Simple Model to Predict Formation of Bromate Ion and Hypobromous Acid/Hypobromite Ion through Hydroxyl Radical Pathway during Ozonation

A simple model is developed to predict the formation of bromate ion as well as hypobromous acid/hypobromite ion through the hydroxyl radical pathway. For simplicity of the model, hydroxyl radical concentrations are represented by the concentration ratio of hydroxyl radical to dissolved ozone under the different pH conditions. A kinetic analysis is conducted to evaluate the ratio under the different pH conditions based on the experimental data. The different extent of the ratio by one pH unit is found to be 3–4 times. This model can favorably simulate the formations of bromate ion as well as hypobromous acid/hypobromite ion in spite of the simplicity of the model. So it is likely that this model will be applicable to the prediction of bromate ion formation in water purification process such as drinking water treatment by introducing the concentration ratio of hydroxyl radical to dissolved ozone.     

Ozonation/Post-Chlorination of Humic Acid: A Model for Predicting Drinking Water Disinfection By-Products

Experiments were performed to evaluate disinfection by-products in model humic acid solutions which were ozonated at three different ozone to carbon levels and then chlorinated. These experiments were conducted in order to help understand whether the ozone/post-chlorination process alters the amount and type of mutagenic by-products formed, from those produced by chlorination of humic acid alone. Disinfection by-products were identified by gas chromatography/mass spectrometry (GC/MS). Samples of clarified and sand-filtered Mississippi River water at a pilotscale drinking water treatment plant in Jefferson Parish, Louisiana, that were ozonated and post-disinfected with chlorine, also were analyzed by GC/MS. A comparison of the by-products in the pilot plant study versus those in our laboratory study showed that similar compounds were produced. The effect of bromide ion in the pilot plant water on by-product formation also is discussed.     

溴甲烷空间熏蒸及其替代

溴甲烷作为一种性能优良的熏蒸剂,一直被广泛应用于耐久储存品、易腐烂商品及建筑物等的熏蒸,在仓储物保护、检疫及装运前熏蒸中发挥着十分重要的作用。但是,溴甲烷是一种耗减臭氧层的物质,已经被列入逐步淘汰的熏蒸剂。为了中国今后能够实施有效的淘汰,本文就目前在耐久储存品和易腐烂商品熏蒸方面替代溴甲烷的主要技术和方法作了简要介绍。