Production and Removal of Assimilable Organic Carbon Under Pilot-Plant Conditions Through the Use of Ozone and PEROXONE

Pilot-plant studies were conducted in two source waters to determine the effects of predisinfection with ozone alone and with a combination of hydrogen peroxide and ozone (PEROXONE) on the production of assimilable organic carbon (AOC) compounds. Colorado River water (CRW) and State project water (SPW) from Northern California were treated with ozone alone at applied dosages ranging from 1 to 4 mg/L and with PEROXONE at hydrogen peroxide/ozone (H₂O₂/O₃) ratios of 0.05, 0.10, 0.20, and 0.30. Ozonation of CRW with applied dosages of 1.0,2.0, and 4.0 mg/L increased AOC concentrations from 70μg C/L to 275, 350, and 224 μg C/L, respectively. Ozonation of SPW with an applied dosage of 4.0 mg/L elevated AOC concentrations from 70 to 522μg C/L.     

Effects of Ozonation on AOC Content of Humic Finnish Groundwater

The effects of ozonation on assimilable organic carbon (AOC) content of humic groundwater were investigated in batch experiments on three different groundwaters used as drinking water in Finland. All water samples had quite high concentrations of iron (range 2–10 mg/L) and manganese (range 0.1–0.2 mg/L) and therefore combined ozonation and filtration is a possible water purification method. The ozone dosage used varied from 0 to 16.6 mgO₃/L (ΔO₃/TOC?=?0–1.6). The ozone treatment increased the AOC concentration in the groundwater samples to different degrees. For example, an ozone dose of 3.9 mg/L increased the AOC concentration in different water as follows: from 49 μg/L to 55/L, from 7 μg/L to 119 μg/L and from 23 μg/L to 226 μg/L.     

Bromate Control by Dosing Hydrogen Peroxide and Ammonia during Ozonation of the Yellow River Water

Ozonation of the downstream Yellow River water yields bromate with concentrations higher than China regulations. Bench tests demonstrated that dosing ammonia or hydrogen peroxide alone could not control the bromate concentration to below 10 μg/L. A pilot study showed that dosing hydrogen peroxide into the inherently ammonia-containing raw water at a dosage lower than 1.7 could effectively reduce the bromate concentration to below the detection limit when the ozone dosage was between 2 and 2.5 mg/L.     

The Evaluation Of Ozonation and Chlorination On Disinfection By-Product Formation for a High-Bromide Water

High-bromide raw water was ozonated or chlorinated with and without hydrogen peroxide to study the effect of the disinfectants on the disinfection by-product (DBP) formation. Less bromate was formed when ozonation was made at the ambient pH of 5.8 as compared to ozonation at pH 7, showing the effectiveness of pH reduction in controlling the bromate formation. When chlorine dose was 1 mg/L instead of 2.3 mg/L, the trihalomethane formation was 50 μg/L instead of >100 μg/L, and the proportional distribution of the trihalomethanes was similar. The use of ozone for this water could provide good results in respect of the DBP formation.     

Kinetic Study and Optimum Control of the Ozone/UV Process Measuring Hydrogen Peroxide Formed In-situ

This study was conducted to develop a kinetic model of the ozone/UV process by monitoring the trend of in-situ hydrogen peroxide formation. A specifically devised setup, which could continuously measure the concentration of hydrogen peroxide as low as 10 μg/L, was used. The kinetic equations, comprised of several intrinsic constants with semi-empirical parameters (k_chain and k_R3) were developed to predict the time varied residual ozone and hydrogen peroxide formed in situ along with the hydroxyl radical concentration at steady state,[OH°]_ss, in the ozone/UV process. The optimum ozone dose was also investigated at a fixed UV dose using the removal rate of UV absorbance at 254 nm (A₂₅₄) in raw drinking water. The result showed that the continuous monitoring of hydrogen peroxide formed in situ in an ozone/UV process could be used as an important tool to optimize the operation of the process.     

Performance evaluation of ozonation and an ozone/hydrogen peroxide process toward development of a new sewage treatment process—Focusing on organic compounds and emerging contaminants

Performance of ozonation and an ozone/hydrogen peroxide process under a new concept centering on ozonation and/or ozone/hydrogen peroxide processes in sewage treatment processes comprising only physical and chemical processes are discussed, with focus on the removal of matrix organic compounds and emerging contaminants. Matrix organic compounds of filtrated primary sewage effluents were removed to as low as 3.2 mgC/L in the ozone/hydrogen peroxide process at an ozone consumption of around 400 mg/L. Linear relationships between ozone consumption and removal amounts of organic compounds were observed, in which the amounts of ozone required to remove 1 mg of organic carbon were 9.5 and 8.3 mg (2.4 and 2.1 mol-O₃/mol-C) in ozonation and the ozone/hydrogen peroxide process, respectively. Ratios of hydroxyl radical exposure to ozone exposure were in the order of 10^–9 to 10^–8 for ozonation and 10^–7 to 10^–6 for the ozone/hydrogen peroxide process. Experiments and a kinetic evaluation showed that ozonation and/or the ozone/hydrogen peroxide process have high elimination capability for emerging contaminants, even in primary sewage effluent with the thorough removal of matrix organic compounds. Newly found reaction phenomena, the temporal increase and decrease of dissolved ozone and accumulation of hydrogen peroxide in the early stage of oxidation with the continuous feeding of hydrogen peroxide, were presented. Possible reaction mechanisms are also discussed.     

Removal of Atrazine Through Ozonation in the Presence of Humic Substances

The presence of pesticides in water sources and their removal by treatment processes is of particular interest currently to water companies and research scientists. Although operators and scientists are debating whether the related standards and legislation are too stringent, the current European Drinking Water Directive stipulates a maximum contaminant level (MCL) of 0.1 μg/L for an individual pesticide. Atrazine is amongst the most frequently identified pesticides in water supply sources. Since conventional treatment processes (chlorination, coagulation and filtration) are unable to reduce this micropollutant to an acceptable concentration, two advanced technologies are being investigated extensively; namely, adsorption onto activated carbon, and ozonation, particularly ozone combined with hydrogen peroxide. As for ozonation, several authors (Glaze et al., 1987; McGuire and Gaston, 1988; Terashima, 1988; Ferguson et al., 1991) have reported that the removal of refractory organics (e.g., 2-methyl isoborneol – MIB and geosmin) by ozone appears to be more effective in natural waters than in pure water solution; this was attributed to the action of natural organic material in water (such as humic substances) which promotes the radical reactions of ozone. In other more fundamental studies (Staehelin and Hoigné, 1985; Xiong and Legube, 1991), humic substances were speculated to be involved in radical decomposition of ozone in solution.     

Degradation Of Selected Herbicides In A Lowland Surface Water By Ozone And Ozone-Hydrogen Peroxide

The efficiency of ozone, and ozone in combination with hydrogen peroxide, for the degradation of five herbicides: Atrazine, Benazolin, Bentazone, Imazapyr and Triclopyr, under controlled laboratory conditions was investigated. Experiments were conducted at pH 7.5 in a bubble contactor column with a raw lowland surface water spiked with initial active ingredient concentrations of 2 μg/L. Mean consumed ozone doses were approximately 1, 2 and 3 mg O₃/L. Hydrogen peroxide was added simultaneously to the application of ozone in a series of six mass ratios, between 0.0 and 1.0, with each of the consumed ozone doses. The results demonstrated a greater but varying removal of all herbicides achieved with increasing consumed ozone and applied hydrogen peroxide doses.     

Improvement in the Effectiveness of Ozonation of Drinking Water Through the Use of Hydrogen Peroxide

Addition of hydrogen peroxide to water during ozonation increases the rate of oxidation of organic compounds and ozone transfer. Coupling ozone with hydrogen peroxide can increase the efficiency of a drinking water treatment line, for example in removing THM precursors. To optimize this oxidation process, the quantity of hydrogen peroxide added and the point of injection must be carefully selected.     

Removal Characteristics of Organic Pollutants in Sewage Treatment by a Pre-Coagulation,Ozonation and Ozone/Hydrogen Peroxide Process

The applicability of a sequential process of ozonation and ozone/hydrogen peroxide process for the removal of soluble organic compounds from a pre-coagulated municipal sewage was examined. 6–25% of initial T-COD_Cr was removed at the early stage of ozonation before the ratio of consumed ozone to removed T-COD_Cr dramatically increased. Until dissolved ozone was detected, 0.3 mgO₃/mgTOC₀ (Initial TOC) of ozone was consumed. When an ozone/hydrogen peroxide process was applied, additional COD_Cr was removed. And we elucidated that two following findings are important for the better performance of ozone/hydrogen peroxide process; those are to remove readily reactive organic compounds with ozone before the application of ozone/hydrogen peroxide process and to avoid the excess addition of hydrogen peroxide. Based on these two findings, we proposed a sequential process of ozonation and multi-stage ozone/hydrogen peroxide process and the appropriate addition of hydrogen peroxide. T-COD_Cr, TOC and ATU-BOD₅ were reduced to less than 7 mg/L, 6 mgC/L and 5 mg/L, respectively after total treatment time of 79 min. Furthermore, we discussed the transformation of organic compounds and the removal of organic compounds. The removal amount of COD_Cr and UV₂₅₄ had good linear relationship until the removal amounts of COD_Cr and UV₂₅₄ were 30 mg/L and 0.11 cm^?1, respectively. Therefore UV₂₅₄ would be useful for an indicator for COD_Cr removal at the beginning of the treatment. The accumulation of carboxylic acids (formic acid, acetic acid and oxalic acid) was observed. The ratio of carbon concentration of carboxylic acids to TOC remaining was getting higher and reached around 0.5 finally. Removal of TOC was observed with the accumulation of carboxylic acids. When unknown organic compounds (organic compounds except for carboxylic acids) were oxidized, 70% was apparently removed as carbon dioxide and 30% was accumulated as carboxylic acids. A portion of biodegradable organic compounds to whole organic compounds was enhanced as shown by the increase ratio of BOD/COD_Cr.     

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.     

Organohalogen Formation During Oxidative Sludge Bulking Control

Effluent quality implications of bulking control with chlorine, hydrogen peroxide and ozone in activated sludge treatment have been studied on laboratory scale. Batch chlorination of sludge samples led to the formation of trihalomethanes, mainly as chloroform, in hundreds of μg/L and even more non-specified organohalogens. Most organohalogens detected were formed from substances in the effluent and fewer out of the sludge solids. The presence of sludge lessened the concentration of extractable trihalomethanes in the effluent. Ozone or hydrogen peroxide addition did not lead to the formation of any organohalogens. Continuous chlorination in a laboratory scale activated sludge plant did not produce measurable quantities of any organohalogen compounds.     

Pilot-Plant-Scale Ozone and PEROXONE Disinfection of Giardia muris Seeded into Surface Water Supplies

PEROXONE is an advanced oxidation process for water treatment which is generated by combining ozone and hydrogen peroxide. In this study, surface water supplies were seeded with viable Giardia muris cysts and disinfected by ozone and PEROXONE in the pretreatment columns of a 22.7 L/min pilot plant. Inactivation was examined in two source waters under conditions of varying applied ozone doses (0.5–4.0 mg/L), with and without the addition of hydrogen peroxide; at increasing contact times (3, 6, 9, and 12 min); and with and without added high turbidity (10 and 50 NTU). Approximately 10⁸ viable G. muris cysts were injected into the ozone contactor-column influent. The cysts were collected at the ozone contactor-column effluent and concentrated, and viability was then determined using in vitro excystation.     

Ozone Versus Ozone/Peroxide Induced Particle Destabilization And Aggregation: A Pilot Study

This research compares the role of ozone and the conjunctive use of ozone plus hydrogen peroxide in particle destabilization and particle aggregation, and improvement in filtered water quality. Particle destabilization was observed at all doses of ozone and ozone/peroxide studied, whereas aggregation was observed with ozone only at lower doses (> 2 mg/L) and in conjunction with ozone/peroxide (all doses studied). As compared to alum alone, the ozone-plus-alum and ozone/peroxide-plus-alum treatments provided improved flocculation and better filtered water quality. In addition, each of these preoxidations significantly reduced alum requirements. Overall, in terms of particle destabilization and aggregation; i.e., effectiveness as a coagulation aid, Ozone/peroxide performed better than ozone.     

Combination of Ozonation and the Fenton Processes for Landfill Leachate Treatment: Evaluation of Treatment Efficiency

Single processes such as ozonation, ozone/hydrogen peroxide, Fenton and several combined treatment schemes were applied for leachate collected from a waste disposal site. The implementation of combined Fenton and ozonation processes resulted in the highest chemical oxygen demand removal (77% from initial value) among all the treatment methods applied, while biodegradability improvement was observed during the Fenton pre-treatment only. Some decrease of chemical oxygen demand was obtained during the single ozonation or combined schemes including ozone resulting in slight if any biodegradability improvement. The addition of hydrogen peroxide to ozonation did not enhance chemical oxygen demand, dissolved organic carbon or biochemical oxygen demand removal compared to ozone alone. Ferric chloride coagulation used as a pre-treatment stage did not improve subsequent chemical oxygen demand removal by ozonation or the Fenton processes. Taking into account the effective chemical oxygen demand, dissolved organic carbon removal and biodegradability improvement the single Fenton process seems to be a preferable treatment method for the leachate treatment. Some reduction in toxicity to Daphnia magna was observed after the application of the studied treatment methods.     

Costs of Advanced Treatment in Water Reclamation

The additional removal of trace organic contaminants (TOrCs) provided by advanced water and wastewater treatment inevitably requires additional financial costs, which must be estimated to support utility planning and compare alternatives. This study presents conceptual-level (Class 4) capital and annual operations and maintenance (O&M) cost curve equations to aid evaluations of advanced treatment trains for water reuse. The cost curve equations are broadly applicable to the water reuse community, particularly those interested in ozone-based treatment trains. Unit processes include microfiltration or ultrafiltration membranes (MF/UF), nanofiltration or reverse osmosis membranes (NF/RO), ozone (with or without hydrogen peroxide, H₂O₂), ultraviolet (UV) treatment with H₂O₂ (UV/H₂O₂), and biological activated carbon (BAC); all cost curves are for a unit process and can be added together to obtain costs for a combined treatment train. The cost curves indicate that at all plant capacities (1 to 500 MGD), membrane treatment (e.g., MF or RO) represents the highest cost unit process, ozone the least, and BAC or UV/H₂O₂ fall in between. Additionally, the relationship between ozone dose and TOrC removal is discussed with a demonstration of how costs change with increasing ozone dose to achieve desired TOrC destruction.     

废水中氨及甲苯的O3／H2O2氧化降解及其动力学

研究了废水中的无机污染物氨和有机污染物甲苯在Ｏ３／Ｈ２Ｏ２ 中的氧化降解过程。根据Ｏ３／Ｈ２Ｏ２ 反应产生自由基ＯＨ·的机理和污染物在Ｏ３／Ｈ２Ｏ２ 中的氧化降解过程,推导出污染物被Ｏ３／Ｈ２Ｏ２氧化降解时的动力学模型,实验结果与理论模型相符。     

壬二酸联合氧化法的合成与反应机理初探

对以过氧化氢和臭氧联合为氧化剂,油酸为原料制备壬二酸的工艺进行了研究,考察了不同的过氧化氢的质量分数、通入臭氧的流速以及不同种类钨化合物与季铵盐组成的相转移催化体系催化氧化油酸的反应活性,实验结果表明:以20 g油酸为原料,加入0.6 g磷钨酸,0.7 g CTAB,滴加ω(H2O2)=30%60 mL,温度70℃,通入臭氧8 h,壬二酸的收率为71%.初步研究了臭氧-过氧化氢联合氧化法制备壬二酸的反应杌理,发现·0H是一个重要的反应物.     

Ozonation Of Wastewater Resulting From The Production Of Organochlorine Plaguicides Derived From DDT And Trichlorobenzene

In this work, a first step has been made in the characterization of the organic pollutants found in the residual water from the production of dicofol and tetradifon pesticides, derived from DDT and trichlorobenzene, respectively. The behavior of the effluent also was studied using degradation techniques - treatment with ozone and ozone combined with hydrogen peroxide - and the results compared by means of the pH, conductivity, TOC, COD, TOX, ecotoxicity, GC/ECD and GC/MS analysis of the samples after the treatment.     

Gallic acid water ozonation using activated carbon

The ozonation of gallic acid in water in the presence of activated carbon has been studied at pH 5. Hydrogen peroxide, ketomalonic and oxalic acids were identified as by-products. The process involves two main periods of reaction. The first period, up to complete disappearance of gallic acid, during which ozonation rates are slightly improved by the presence of activated carbon. The second one, during which activated carbon plays an important role as promoter, and total mineralization of the organic content of the water is achieved. The organic matter removal is due to the sum of contributions of ozone direct reactions and adsorption during the first period and to a free radical mechanism likely involving surface reactions of ozone and hydrogen peroxide on the carbon surface during the second period. There is a third transition period where by-products concentration reach maximum values and ozonation is likely due to both direct and free radical mechanisms involving ozone and adsorption. Discussion on the mechanism and kinetics of the process is also presented both for single ozonation and activated carbon ozonation.