Bromate Ion Formation Research Articles

Online monitoring of bromate in treated wastewater: implications for potable water reuse

An online bromate ion analyzer coupled with a nanofiltration membrane-based pre-treatment system can monitor bromate ion formation during wastewater ozonation.

Benefits of ozonation before activated carbon adsorption for the removal of organic micropollutants from wastewater effluents.

Advanced processes for the removal of organic micropollutants (OMPs) from wastewater effluents include adsorption onto activated carbon, ozonation, or a combination of both processes. The removal of 28 OMPs present in a real wastewater effluent was studied by ozonation coupled to activated carbon adsorption and compared to a sole adsorption. The influence of the specific ozone dose (0.09-1.29 gO3/gDOC) and the influence of the powdered activated carbon (PAC) dose (2, 5 and 10mg/L) were first studied separately. OMPs removal increased with both the specific ozone dose (up to 80% for a dose higher than 0.60 gO3/gDOC) and the PAC dose. Ozonation performances decreased in presence of suspended solids, which were converted to dissolved organic carbon. A correction of the specific ozone dose according to the suspended solids levels, in addition to nitrite, should be considered. The influence of ozonation (0.09, 0.22, 0.94 and 1.29 gO3/gDOC) on OMPs adsorption was then assessed. OMPs adsorption didn't change at low specific ozone doses but increased at higher specific ozone doses due to a decrease in DOM adsorption and competition with OMPs. At low ozone doses followed by adsorption (0.22 gO3/gDOC and 10mg/L PAC), the two processes appeared complementary as OMPs with a low reactivity toward ozone were well absorbed onto PAC while most OMPs refractory to adsorption were well eliminated by ozone. Improved removals were obtained for all compounds with these selected doses, reaching more than 80% removal for most OMPs while limiting the formation of bromate ion.

Advances in Treatment of Brominated Hydrocarbons by Heterogeneous Catalytic Ozonation and Bromate Minimization.

The formation of carcinogenic bromate ions is a constraint when ozone is used for the remediation of water containing brominated organic materials. With its strong oxidizing ability, ozone rapidly transforms bromide in aqueous media to bromate, through a series of reactions involving hydroxyl radicals. Several strategies, such as limiting the ozone concentration, maintaining pH < 6, or the use of ammonia or hydrogen peroxide were explored to minimize bromate generation. However, most of the above strategies had a negative effect on the ozonation efficiency. The advanced oxidation processes, using catalysts together with ozone, have proven to be a promising technology for the degradation of pollutants in wastewater, but very few studies have been conducted to find ways to minimize bromate formation during this approach. The proposed article, therefore, presents a comprehensive review on recent advances in bromate reduction in water by catalytic ozonation and proposes reaction mechanisms associated with the catalytic process. The main aim is to highlight any gaps in the reported studies, thus creating a platform for future research and a quest to find environment friendly and efficacious catalysts for minimizing bromate formation in aqueous media during ozonation of brominated organic compounds.

Effect of oxidation–reduction potential on an electrochemical Fenton-type process

Abstract This paper reports the relationship between oxidation–reduction potential (ORP), current density and formation of byproducts in an electrochemical Fenton-type process. The ORP at current densities >14.3 mA/cm2 using bromide-free water quickly increased to over 1000 mV, which indicated the accumulation of hypochlorous acid (HOCl) in water. The current efficiency (CE) for 1,4-dioxane removal strongly depended on the current density and ORP. Both low and high current densities deteriorated the CE owing to the imbalance in the rates of generation of ferrous ions and HOCl. When a high CE was observed, the ORP was smaller by 100–140 mV than that in the HOCl rich condition. The formation of chlorate and bromate ions was enhanced when the current density was increased. However, the formation of these ions was significantly constrained at the optimal current density. The optimal current density depended on the composition of wastewater, and it shifted to relatively lower values upon the addition of Br−, whereas the ORP, under optimal conditions, was more stable compared to the current density. Consequently, the ORP was considered to be a more suitable indicator for the optimal operation of the electrochemical Fenton-type process compared to the current density.

On the formation of bromate and chlorate ions during electrolysis with boron doped diamond anode for seawater treatment

AbstractBACKGROUNDThe electrochemical treatment of brackish and seawaters with boron doped diamond anodes (BDD) can be particularly suitable for the removal of microorganisms, microalgae and pollutants: the high conductivity of these waters and the high content of chloride ions can be exploited in disinfection/oxidation processes mediated by active chlorine. A correct choice of operating conditions can limit the formation of such undesired by‐products as bromate and chlorate ions.RESULTSGalvanostatic electrolyses of synthetic waters containing chloride and/or bromide ions using BDD anode were carried out both in batch and continuous mode in an undivided cell. Bromide ions were oxidized to form bromate ions with high conversion rate, while chlorate ions were found as by‐products of the oxidation of chloride ions together with active chlorine. When solutions containing Br− and Cl− were treated, the increase in the concentration of chloride up to that of seawater (20 g dm−3), hinders the formation of BrO3− and ClO3−.CONCLUSIONSThe electrochemical process with BDD anode could be applicable to the disinfection of high salinity waters: in synthetic solution simulating the composition of seawaters, high amounts of active chlorine are formed and the occurrence of bromates and chlorates is highly limited. © 2013 Society of Chemical Industry

Formation and minimization of bromate ions within non-thermal-plasma advanced oxidation

The formation and minimization of bromate ions as a by-product of the operation of a non-thermal plasma reactor for the removal of refractory organic species from drinking water was investigated. BrO 3 − formation kinetics was found to be 1st order with respect to the Br − concentration. BrO 3 − formation increased when the organic pollutant concentration fell below a threshold value, intrinsic to each organic species. Formation also increased when dissolved ozone concentration was elevated by injection of O 3-rich air, generated inside the reactor, back to the water, although measured O 3 concentrations were low (~0.1 mg/l). BrO 3 − formation significantly decreased at high temperatures (>35 °C) and low pH (~pH6.0) values and was found insensitive to the carbonate alkalinity concentration. Dosage of hypochlorite followed by ammonia to the inlet water was found to be more effective in minimizing bromate formation than ammonia dosage alone. A general method was developed for assessing the relative importance of the various possible bromate formation pathways within plasma reactors, and a probable dominant BrO 3 − formation reaction sequence was suggested for the particular conditions prevailing in non-thermal plasma systems.

Bromate formation during ozonation of drinking water: A response surface methodology study

The use of ozone in water treatment encounters the bromate formation hindrance. If raw water contains bromide, bromate will be formed in the ozonation step. Because bromate is well known as a carcinogenic, it is very important to optimize the treatment process and minimize or eliminate the bromate formation. Response surface optimization methodology (three-variable, three-level experiment Box–Behnken design) was applied in a pilot plant to investigate the effect of operating conditions (pH, initial bromide concentration, and exposure time) on bromate ion formation. Results showed that most of the investigated water facilities have water that exceeds the international standards of bromate content. It also showed that bromate formation is maximum when the pH is close to 9. Bromate formation also favors higher initial bromide concentrations. However, further increase in initial bromide concentration will cause the bromate to be reduced to bromine (Br 2) by excess bromide (Br −).

Simultaneous Control of Bromate Ion and Chlorinous Odor in Drinking Water Using an Advanced Oxidation Process (O3/H2O2)

Simultaneous control of chlorinous odor and bromate ion formation was attempted by using an advanced oxidation process (AOP, O3/H2O2). Also, the relationship between trichloramine (NCl3, a suspected odor compound in drinking water) and chlorinous odor in drinking water was studied through a headspace GC-MS analysis and the triangle sensory test. Odor strength after chlorination decreased by more than 50% for the samples pretreated with conventional ozonation and AOP. The change of hydroxyl radical exposure (•OH-ct) when AOP was applied did not show the clear difference in terms of the removal of chlorinous odor compared with conventional ozonation, but AOP was better for the control of bromate ion. Trichloramine seemed not to be a major odor compound in the chlorinated water of this experiment. The change of ammonium ion, bromide ion, and ozone dose did not clearly affect the efficiency of odor removal.

O3/H2O2 Process for Both Removal of Odorous Algal-Derived Compounds and Control of Bromate Ion Formation

The limitation of ozonation and the applicability of ozone/hydrogen peroxide process with a source water for a water supply using a flow-through type contactor were discussed. The water sample was pre-treated in a lab and spiked with bromide ion in the concentration range from 39 to 515 μg/L, and both 2-MIB and geosmin, odorous algal-derived compounds, from 58 to 609 ng/L under the hydrogen peroxide dose of 0 to 3.7 mg/L. When the initial concentration of Br− was around 50 μg/L, the formation of BrO3 − was controlled at less than 10 μg/L at the ozone dose of 2 mg/L, however the concentration of 2-MIB was over 10 ng/L in some cases with its initial concentration of around 100 ng/L during ozonation. When the initial concentration of Br− exceeds 100 μg/L, it seems very difficult to meet the standard for drinking water quality even with the initial 2-MIB concentration of 100 ng/L. The dose of H2O2 from 0.5 to 2.3 mg/L attained the standard for drinking water quality with the initial concentrations of Br− of approximately 50 μg/L and of 2-MIB of up to 500 ng/L at the ozone dose of 2 mg/L. When the initial concentration of 2-MIB was around 100 ng/L with the initial Br− concentration of up to 200 μg/L, the H2O2 dose of 1.7 mg/L also attained the standard for drinking water quality. When the initial concentration of Br− was around 500 μg/L, although the higher dose of H2O2 was required for the control of BrO3 − formation and the increase of the initial concentration of 2-MIB requires more H2O2 dose, the higher dose of H2O2 could attain the standard for drinking water quality of BrO3 − and 2-MIB (geosmin) simultaneously.

Bromate ion formation in dark chlorination and ultraviolet/chlorination processes for bromide-containing water

Bormate (BrO 3 −) is a carcinogenic chemical produced in ozonation or chlorination of bromide-containing water. Although its formation in seawater with or without sunlight has been previously investigated, the formation of bromate in dilute solutions, particularly raw water for water treatment plant, is unknown. In this article, the results of bench scale tests to measure the formation rates of bromate formation in dilute solutions, including de-ionized water and raw water from Yangtze River, were presented in dark chlorination and ultraviolet (UV)/chlorination processes. And the effects of initial pH, initial concentration of NaOCl, and UV light intensity on bromate formation in UV/chlorination of the diluted solutions were investigated. Detectable bromate was formed in dark chlorination of the two water samples with a relatively slow production rate. Under routine disinfecting conditions, the amount of formed bromate is not likely to exceed the national standards (10 μg/L). UV irradiation enhanced the decay of free chlorine, and, simultaneously, 6.6%–32% of Br − was oxidized to BrO 3 −. And the formation of bromate exhibited three stages: rapid stage, slow stage and plateau. Under the experimental conditions (pH = 4.41–11.07, C Cl 2= 1.23–4.50 mg/L), low pH and high chlorine concentration favored the generation of bromate. High light intensity promoted the production rate of bromate, but decreased its total generation amount due to acceleration of chlorine decomposition.

Formation and Reverse Osmosis Removal of Bromate Ions during Ozonation of Groundwater in Coastal Areas

The generation of bromate ions during ozonation of groundwater samples affected by seawater intrusion was investigated. The ozone‐water contact times studied were 2.5, 5, 10, 15, and 30 min, while the applied ozone rate was 4.5 mg/min. Generation of bromate ions started right after the application of ozone. The level of bromates increased with time as more ozone was added to the reactor. Even after 30 min of ozonation, the concentration of bromates kept rising without reaching a plateau. The higher the initial concentration of bromide ions, the higher the level of bromate ions in the ozonated water sample. The experimental results obtained during ozonation of the specific groundwater samples (low TOC and low ammonia concentrations) were used in order to develop a mathematical model capable of forecasting the generation of bromate ions. The empirical model containing two independent variables, conductivity and contact time, was: This model allows the prediction of bromate ion generation, when the groundwater conductivity and the contact time are known, for an ozone application rate around 4.5 mg/min. Finally, the ozonated water was treated by reverse osmosis. The removal of bromate ions reached 96.1%. Equivalent reduction in the conductivity of the water was also achieved.

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.

The Control of Brominated By-products and the Removal of Organic Pollutants during the Ozone/Hydrogen Peroxide Treatment of Secondary Effluent

This study aims to establish appropriate conditions to control the formation of bromate ion and brominated organic compounds during the O3/H2O2 treatment of the secondary effluents of sewage. When the H2O2/O3 mole ratio of injection was above 0.5 and the dissolved ozone concentration was below 0.1 mg/L, bromate ion formation was controlled, and treatment purposes such as the reduction of estrogenic activity or organic matter were completed. The formation of TOBr and individual brominated organic compounds during O3/H2O2 treatment was also completely controlled.

Ozonation parameter for removal of oestrogenicity from secondary effluent without by-products

The purposes of this study are to investigate ozonation characteristics, to evaluate oestrogenicity and to confirm behaviours of by-products during ozonation of secondary effluent. For the ozonation of secondary effluent, TOC was decreased only 10% when 4 (mgO3/mgC) of ozone consumption per initial TOC. However, UV254 and SUVA was decreased approximately 65% until ozone consumption of 2 (mgO3/mgC). Ozonation was also shown to be very effective for decrease of oestrogenicity in secondary effluent. Bromate ion started to form obviously when the ozone consumption per initial TOC exceeded 2 (mgO3/mgC) and increased while the time of ozonation became longer. From these results, ozone consumption per initial TOC was shown to be an appropriate operation parameter to reduce SUVA effectively and E2 equivalent concentration to less than 0.1 nM without significant formation of bromate ion, and its value was determined to be 2 (mgO3/mgC) in ozonation of secondary effluent.

Adsorptive ozonation of 2-methylisoborneol in natural water with preventing bromate formation

This paper presents an application of our newly developed adsorptive ozonation process using a high silica zeolite adsorbent (USY) for drinking water treatment. First, the adsorption of 2-methylisoborneol (2-MIB) on USY in a river water/pure water mixture was clarified by a batch-type adsorption experiment. The results showed that 2-MIB was adsorbed on USY; however, almost all of the adsorbed 2-MIB was desorbed over time. The desorption rate was increased with the ratio of river water to pure water, indicating that compounds dissolved in the river water, such as natural organic matter (NOM), prevent the adsorption of 2-MIB on USY. Second, the ability of the river water to consume ozone was confirmed in an experiment using a USY-packed column reactor. The ozone consumption was obviously increased by the presence of USY, indicating that USY-adsorbing compounds dissolved in the river water (probably small size NOM) consumed the ozone. However, the rapid ozone consumption was occurred by 6–8 s in the retention times when 3.14–4.38 mg L −1 of water dissolved ozone was fed, this rapid ozone consumption lasted no more than these times. This result revealed that the rapid consumption of ozone by the adsorptive compounds in our process could be avoided within a certain retention time (6–8 s; especially for the river water used in this study) when enough concentration of ozone (3.14 mg L −1 or more; same above) was supplied. We therefore performed a trial in which 2-MIB dissolved in river water was continuously decomposed using a USY-packed column with various ozone concentrations. In the process, the adsorptive compound dissolved in the river water adsorbed and reacted with ozone in the parts of the apparatus upstream of the column, while the adsorption and decomposition of 2-MIB took place in the parts of the apparatus downstream of the column. This resulted in a sufficient 2-MIB decomposition with minimizing bromate ion formation.

Bromate formation during ozonation of groundwater in coastal areas in Greece

This project studied bromate ion formation during ozonation of groundwater containing elevated bromide ion levels. Groundwater samples from aquifers in coastal areas were ozonated in a semi-batch reactor under typical ozonation conditions sufficient to inactivate microorganisms. Ozone dose and contact time played a significant role in bromate ion production. Bromate formation increased as the contact time increased under the same ozone dose. In addition, increasing the ozone dose while keeping a constant contact time resulted in increasing bromate formation. Further parameters that influenced the formation of bromate ions were the initial concentration of bromide ion and the product CT (ozone dose times contact time), which has been suggested as a control variable for effective ozonation. Empirical bromate formation models were developed in order to simulate the effect of water quality characteristics and treatment processes on bromate formation. The empirical models were capable of estimating the concentration of bromate ions in ozonated groundwater samples, which contain low concentrations of ammonia and dissolved organic carbon.

塩素処理による臭素酸イオン生成条件の検討

In this study, we investigated the formation condition of bromate ions following chlorination of purified water or of well water containing bromide ions. The formation of bromate ions occurred at room temperature but increased with temperature or pH. In the presence of ultraviolet rays, bromate ions formed rapidly and in high concentrations, but could be almost completely controlled by shading during chlorination. Light irradiation of chlorine-treated well water containing bromide ions also led to formation of bromate ions at concentrations ranging from ND to 60.8 μg·l-1, but concentrations differed greatly between different well water samples. This difference was thought to be the result of differing concentrations of organic matter contained within the different well water samples. We suggest that bromate ion formation is suppressed by the high chlorine concentration used for trihalomethane formation when the organic matter concentration is high, and that these two formation reactions competed for chlorine. There is also a possibility that some organic matter, such as humic materials, directly controls the formation reaction of the bromate ion.

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

ABSTRACT 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.

오존처리에 의한 Bromate의 생성 및 흰쥐의 신장독성에 미치는 영향

브롬(Br-)이온을 포함하는 지표수 또는 해수를 상수원 또는 어류양식용 물로 사용할 경우 소독, 살균을 위하여 오존(O<TEX>$_3$</TEX>)을 많이 사용한다. 이때 물속에 포함되어 있는 브름(Br-) 이온과 오존과의 반응에 의하여 독성물질인 Bromate(BrO<TEX>$_3$</TEX>-)가 산화 부산물로서 생성된다. 이 bromate의 생성반응에 대한 용액의 pH와 반응온도의 영향 및 bromate를 음용수중에 함유시키고 실험동물에 섭취시켰을 때의 생체독성에 미치는 기전을 관찰하였다. Bromate의 생성은 반응온도가 증가할수록 증가되지만, 낮은온도(15<TEX>$^{\circ}C$</TEX>)에서는 용액의 초기 pH가 3 인 경우는 초기 pH가 7, 10 인 용액의 경우보다 훨씬 적은 생성량을 나타내었다. Bromate를 음료수중에 0, 0.1, 0.2, 0.4g/L로하여 4, 12, 16, 20, 24주 투여하고서 신조직중의 지질과산화의 함량이 증가되었으며, 혈중 뇨소질소의 활성 및 뇨중 <TEX>${\gamma}$</TEX>-glutamy-ltransferase의 활성은 대조군에 비하여 bromate의 투여로 현저히 증가되었으며, 뇨중 lactate dehydrogenase의 활성에는 별다른 영향이 없었다. Bromate의 투여로 xanthine oxidase 및 aldehyde oxidase의 활성은 bromate의 투여로 현저히 증가되었으며 glutathione의 농도 및 glutathione S-transferase의 활성도 대조군 보다 현저히 억제되었다. Glutathione의 생성계에 미치는 <TEX>${\gamma}$</TEX>-giutarnylcystein synthetase의 활성은 대조군에 비해 bromate의 투여로 억제되었으며 glutathione redurtase의 활성은 별다른 영향이 없었다. In oder to investigate the effects of pH and temperature on the formation of bromate ion, which is ozonation by-products of bromine containing natural water. At the same intial pH condition, the increase of pH shown similar trends even if the reaction variables such as temperature and reaction time of ozonation were changed. As pH and temperature were increasing, the bromate concentration was increased but bromine components (HOBr/OBr-) were decreased with increasing pH from 3 to 10. Lipid peroxide content in the kidney was increased by bromate which was ingestion with 0.4g/L for 24 weeks in drinking water. Renal cytosolic enzyme system (XO, AO) of bromate group were significantly increased in comparison with those of normal group. But microsomal enzyme system were not affected. BUN level and urinary <TEX>${\gamma}$</TEX>-glutamyltransferase activity were significantly increased in comparison with those of the normal. But, urinary lactate dehydrogenase activity was not affected. Renal glutathione content of rat was significantly decreased in comparison with those of normal rat given bromate. Renal glutathione S-transferase and <TEX>${\gamma}$</TEX>-glutamylcysteine synthetase activities were significantly decreased in bromate-treated group, but change in renal glutathione reductase activity was not significantly different from any other experimental group.

Examining bromate ion removal by GAC through RSSCT and pilot-scale columns

The ozonation of water containing bromide ion leads to the formation of bromate ion, a suspected human carcinogen. The United States Environmental Protection Agency (US EPA) has recently set a drinking water standard for bromate ion of 10 μg/L. Granular activated carbon was examined through rapid small-scale column (RSSCT) and pilot-scale experiments for bromate ion removal using treated surface water. Adsorption followed by chemical reduction were found to be the removal mechanisms of bromate ion. Removal rates were higher at lower pH levels. The RSSCT provided a good approximation of pilot-scale test performance, although breakthrough of pilot -scale experiments preceded those of RSSCT experiments, which may be attributed to biological or biofilm activity in pilot-scale columns.