The Effect of Bromide ion in Water Treatment. II. A Literature Review of Ozone and Bromide ion Interactions and the Formation of Organic Bromine Compounds

Where bromide ion is found in water used as a source of drinking water, and chlorination is used for disinfection, bromide ion is oxidized to bromine and can result in the formation of organic bromine compounds. There are presently no treatment techniques available for economic removal of bromide ion. A potential treatment strategy is to use an alternative oxidant; ozone is one such alternative. This review presents the reactions of ozone and bromide ion. Understanding of these reactions leads to possible treatment strategies when ozone is used, in the presence of bromide ion, to minimize the formation of trihalomethanes.     

Effects Of Ozone On The Production Of Biodegradable Dissolved Organic Carbon (BDOC) During Water Treatment

This article deals with the oxidation effect of ozone on the increasing fraction of biodegradable organic matter with the “ozotest” method, a laboratory technique which simulates the effect of ozonation and allows a complete oxidation assessment. Ozone treatment was performed on river water samples and sand filter effluent samples. Ozone consumption, reduction of UV absorbance and BDOC formation were monitored with applied ozone doses from 0 to 10 mg/L and with contact times from 0 to 60 min. The BDOC formation was optimum at an applied ozone dose of 0.25-0.5 mg O₃ per mg DOC (contact time = 5 min) corresponding to apparition of traces of residual ozone and maximum UV reduction. Maximum ozone consumption, UV reduction and BDOC formation occurred simultaneously during the first two minutes of treatment. Concerning BDOC formation, applied ozone dose showed a greater effectiveness than contact time. For the same quantity of consumed ozone, a short contact time associated with a high ozone dose was preferable to a long contact time and a low ozone dose.     

Potsdam,New York Water Treatment Plant A Case History

The Village of Potsdam, in northern New York State, is presently building a new water treatment plant. The Village takes its water from the Raquette River. The 2.6 MGD water plant will feature ozonation as a pretreatment to coagulation, sedimentation and filtration. Raquette River water has a high trihalomethane formation potential, due to naturally-occurring organic substances. Ozonation provides a means for predisinfection without formation of trihalomethanes. The anticipated ozone dosage is 2.5 milligrams per liter sufficient ozone to impart aslight residual. Coagulation will be accomplished using aluminum sulfate and sodium alumnate. A nonionic polyelectrolyte will be used as a flocculant aid. The filter media will be Neptune-Microfloc Corp. MF 186. This treatment system was pilot plant tested with excellent results. Trihalomethane Maximum Formation Potential (MTP) was lowered by 67‰, from 353 micrograms per liter to 116 micrograms per liter. Construction contracts for the new plant, scheduled for completion the summer of 1983, tota l $4,443,000.     

Organic matter removal in boiler feed water treatment of a power plant with ozone

The purpose of this work was to test the effectiveness of ozone as a treatment to remove organic matter of the boiler feed water of a power plant. In the experiments carried out in the power plant Endesa in As Pontes (Spain), chlorine was substituted for ozone in the pre‐treatment stage. The use of ozone reduced the organic content of the boiler feed water by an average 20% compared with chlorination and by 50% when ozone was combined with hydrogen peroxide. The latter treatment achieved an organic content in the boiler feed water of less than 40 μg C/L. The ozone treatment also reduced the content of trihalomethanes in the drinking water, produced by the same plant, to values in the range of 10 μg/L and even to undetectable values when ozone was combined with hydrogen peroxide, in spite of the postchlorination applied to this stream to ensure a disinfectant capacity though the distribution system.     

Effects Of Ozone-Hydrogen Peroxide Combination On The Formation Of Biodegradable Dissolved Organic Carbon

The effects of ozone and ozone/hydrogen peroxide on BDOC formation were studied with the “Ozotest” method, a laboratory technique that permits the assessment of oxidation efficiency. Oxidation treatments were performed on river water and sand filter effluent samples. Ozone consumption, reduction of UV absorbance, and BDOC formation were monitored during the experiments. The ratio of 0.35-0.45 mg H₂O₂ per mg O₃ used to degrade pesticides also was optimal for the oxidation of organic matter. BDOC formation versus ozone dose curves with ozone alone or ozone/peroxide system were similar. BDOC formation was optimum at an applied ozone dose of 0.5-1 mg O₃/mg C (contact time = 10 min). The ozone/peroxide system yielded lower BDOC values than ozone alone, a phenomenon related to differences in byproducts generated by the two oxidative systems. Moreover, reduction of the concentration of DOC was higher with ozone/hydrogen peroxide than with ozone alone. For both oxidant systems, BDOC formation occurred during the first minute of treatment.     

Ozone Applications The State-of-the-Art in Switzerland

This paper describes the current state-of-the-art for ozone applications in the processes to prepare drinking water in Switzerland. The Author bases this presentation on the collective Swiss experience of ozone use in water treatment spanning five decades and the design and operation of over 40 water treatment plants.     

The Influence of the Removal of Specific NOM Compounds by Anion Exchange on Ozone Demand,Disinfection Capacity,and Bromate Formation

This research on a pilot scale focuses on the reaction of ozone with natural organic matter (NOM) for three water qualities with different dissolved organic carbon (DOC) concentrations and NOM compositions, obtained after several stages of an anion exchange process. It was shown that for the same ozone dosage per DOC, the ozone demand was higher, less bromate was formed and a lower disinfection capacity was reached for water containing mainly humic substances, than for water where the humic substances were partly removed. It can be concluded that NOM composition, specifically the humic substances, influences the ozone demand, disinfection capacity and bromate formation.     

Modeling Bromate Formation During Ozonation

Bromate formation has been identified as a significant barrier in the application of ozone during water treatment for water sources that contain high levels of bromide. Bromate has been identified as a possible human carcinogen and bromate levels in drinking water are strictly controlled at 10 μg/L in most developed countries. Various models have been proposed to model bromate formation during ozonation based on raw water quality, ozone dose and contact time. Two main approaches for modeling have been used: an empirical regression modeling methodology and kinetic-based methodology. Currently, the benefit of the bromate models lies in their ability to show how process parameters may impact on the amount bromate formed.     

Modeling of Ozonation for Dissolved Ozone Dosing

Experimental research was carried out for calibration and validation of a model describing ozone decay and ozone exposure (CT), decrease in UV absorbance at 254 nm (UVA₂₅₄), increase in assimilable organic carbon concentration and bromate formation. The model proved to be able to predict these parameters on the basis of the applied ozone dosage. The experimental ozone dosages ranged from 0.4 mg-O₃/L to 0.9 mg-O₃/L for natural water with a dissolved organic carbon concentration of 2.4 mg-C/L. The UVA₂₅₄ was found to be an effective parameter for estimation of rapid ozone decay for natural water under experimental conditions tested. The experimental setup consisted of a bench-scale plug flow reactor (approximately 100 L/h) with dissolved ozone dosing.     

The Use Of High Concentration Ozone For Water Treatment

The use of high concentration ozone (HCO) in potable water treatment has been examined at laboratory scale with a gaseous concentration of 19% w/w. This has been compared with conventionally generated ozone at 1.5% w/w. The results of the study have shown that greater transfer efficiencies and higher ozone residuals are possible with HCO. In addition, faster rates of atrazine removal and significantly greater reductions in color and trihalomethane formation potential (THMFP) were observed with HCO.     

Changes in Ozone Demand of Water During the Treatment Process

The protocol for the measurement of ozone demand of water and the change in the dissolved ozone residual with time, using the Gas Ozone Test (GOT) was applied in monitoring water quality of two water treatment facilities. The change in the ozone concentration of water as a function of time was measured for each sample. The resulting half-time was correlated with the ozone dosage, although this parameter does not appear to be directly linked to the characteristics of the water samples studied. The change in the ozone concentration of water as a function of time and ozone dose, measured by the GOT, has direct applications in the sizing of ozonation reactors.     

Applications of Ozone Decomposition Models

Simulated ozone decomposition profiles in “pure” water were made using two analytical kinetic ozone decomposition models and contrasted with experimental and literature data. Fundamental and applied applications of ozone consumption models are presented, demonstrating the importance of both direct and indirect oxidation of inorganic and organic species. A novel approach to simulating ozone decomposition in the presence of natural organic matter (NOM) is presented, concluding that NOM predominantly behaves as a direct consumer of ozone and promoter of ozone decomposition.     

Distribution of Ozone over Urban Kolkata: Observed vs. UAM-V Prediction

Vehicular pollution, emissions due to burning of fossil fuel from industries and nonpoint sources in Kolkata are major sources of air pollution characterized by oxides of Nitrogen (NOx) and volatile organic compounds (VOCs). These pollutants are also responsible for the secondary ozone formation based on their reactivities. In the present study ozone has been monitored hourly every month in residential, industrial, traffic intersections, and petrol pumps in the urban area of Kolkata along with eight hourly nonoxygenated VOCs, carbonyls and NOx. Urban Airshed Model (UAM-V) has been used to simulate ozone on January 14, 2008 in Kolkata’s urban Area. Results of predicted ground level ozone have been in agreement with observed ozone concentrations.     

Mass Balance Analysis of Ozone in a Conventional Bubble Column

Ozone transfer into potable water was studied in a conventional bubble column, and ozone mass balances have been calculated to determine ozone utilization efficiencies. Liquid and gas flow rates, as well as inlet ozone concentrations in the gas phase were varied. Using these data, it was possible to determine the ozone mass transfer coefficient, ozone transfer efficiency, and ozone consumption. A model of ozone transfer was established, and procedures for calculating the optimum design parameters and operating conditions are proposed.     

Destruction of Volatile Organic Contaminants in Drinking Water by Ozone Treatment

Controlled, pilot-plant ozone treatment tests were conducted on twenty-nine volatile organic contaminants in distilled water and groundwater. Results show that aromatic compounds and alkenes are well removed by ozone treatment, but that alkanes are poorly removed. Also, efficiency of destruction improved for the alkenes and aromatic compounds with increasing applied ozone dosage and, for some alkanes, with increasing pH. For most compounds, the efficacy of ozone was not severely affected by the background water matrix. Generally, information gathered from the literature regarding rate constants for the ozone treatment of compounds in the gaseous phase or in organic solution predicted, to a useful degree, the effectiveness of ozone in treating aqueous solutions in the present study.

Several of the test conditions selected for this preliminary study may be similar to those found in drinking water treatment plants. Consequently the findings of this research may help guide utilities in their choice of alternative treatments to meet Maximum Contaminant Levels for volatile organic contaminants such as trichloroethylene and benzene.     

Ozone Treatment of Secondary Effluent at U.S. Municipal Wastewater Treatment Plants

Ozone is a strong oxidant used to treat a variety of constituents in potable water, wastewater, water reuse, and industrial water treatment applications. Ozone is effective at oxidizing a wide range of organic and inorganic compounds and disinfection. Well-known in potable water treatment, with about 400 US installations and 3,000 world-wide, ozone has limited application at wastewater treatments, with less than 10 operating facilities in the US. The ability of ozone to significantly reduce low level concentrations of trace organic compounds, including endocrine disrupting chemicals (EDCs), pharmaceuticals and personal care products (PPCPs), and other emerging contaminants have increased interest in applying ozone in potable water and wastewater treatment. Treating at the point source discharge rather than the water supply intake may be more effective. A recent American Water Works Research Foundation (AwwaRF) report indicated high removals of many EDCs and PPCPs at typical disinfection doses. Several wastewater utilities have installed or are in the process of installing ozone to treat secondary effluent. These utilities are using ozone in a variety of ways: as a primary disinfectant, for treatment of microconstituents, and in combination with other processes (e.g. membranes and UV) to produce high-quality water for indirect potable reuse (IPR). The different applications, treatment goals and basis of process selection are compared and contrasted. Secondary benefits of ozone treatment of secondary effluent, including the use of off-gas in biological treatment is also discussed.     

Removal of Residual Dissolved Ozone with Manganese Dioxide for Process Control with UV254

Ozonation is one of the most promising options to remove organic micropollutants (OMP) from wastewater treatment plant effluents. For an economic operation and in order to avoid formation of bromate, the ozone dose has to be adjusted in real-time due to the strongly varying effluent quality. The reduction of UV absorption at 254 nm (?UV₂₅₄) is a useful surrogate parameter for OMP removals. Unfortunately dissolved ozone also absorbs UV at 254 nm and therefore might disturb a ?UV₂₅₄-based process control. A fixed bed of manganese dioxide granules was found to efficiently remove residual ozone.     

Multistage Ozone Treatment of Dye Waste

An ozonation technology to treat lightly loaded effluents from dye manufacturing processes has been developed. The process uses airgenerated ozone and countercurrent contactors. An intermediate step is included to eliminate OH-radical scavengers and slowly reacting oxidized species from the liquid phase.

A study of ozone efficiency and yield concerning the reduction of TOC and COD levels is presented. The biological degradability.of treated water is discussed. A design and rating calculation procedure for countercurrent contactors is presented. Various waste treatment strategies using separation processes and ozone are discussed briefly. A cost estimate to treat a typical dye effluent in two stages on industrial scale is included.     

Huangpu River water treatment by microfiltration with ozone pretreatment

With the promulgation of more stringent regulations to guarantee the quality of drinking water, low pressure membrane processes are nowadays considered for surface water treatment. But these membranes are sensitive to fouling. In this study ozone is introduced to pretreatment for membrane filtration to get a high quality permeate and improve membrane performance. The organic matter characteristics, such as AMWD of organic matter, hydrophilic/hydrophobic fractions were studied with ozone oxidation. Results show that for Huangpu River water, ozone oxidation offers high percentage of UV absorbance removal than DOC removal. Highest removal of DOC and UV₂₅₄ of 10% and 71% respectively were observed. The dominant organic matter oxidized by ozone was 2-7.0 kDa in terms of molecule distribution investigation. Ozone oxidizes more hydrophobic fraction to hydrophilic one. Changes of organic matter composition improved membrane flux. There is the optimal dosage with ozone of 1.5 mgO₃/L made membrane flux maximum during 0.5-3.0 mgO₃/L ozone dosage. Ozone oxidization provided degradation of macromolecule organic matter, which is responsible to membrane fouling, to small molecule organic substance. Study about the chemical cleaning of the fouled membrane also supports the point that membrane fouling is produced by the organic substance with high molecule weight.     

Ozone Side-Stream Design Options and Operating Considerations

Disinfection with ozone is achieved by CT product, where “C” is residual ozone concentration and “T” is reaction time. Ozone residual is developed after ozone gas is dissolved into the water. Ozone dissolution is most often achieved by either bubble-diffuser or side-stream ozone systems. Side-stream ozone systems are different from bubble-diffuser ozone systems in many ways: 1) Ozone addition occurs outside of the ozone contactor; 2) additional energy is used due to side-stream pump operation; 3) equipment maintenance can be completed independent of ozone contactor operation; 4) ozone contactor size and shape can have unique design features, such as pipeline contacting or shallow-depth basins. Side-stream ozonation is a treatment technique that is gaining in popularity at larger and larger plants. Ozone generators can now operate at elevated ozone concentration, which improves the economics for installing and operating side-stream processes. Two different side-stream arrangements are discussed in this paper. The arrangements differ with the presence or absence of a de-gas vessel. The de-gas vessel option is more expensive in terms of capital and operating cost, but might be the chosen option for particular contactor configurations. Issues and considerations for installing a de-gas vessel are discussed in this paper.