The Combination of Ozone/Hydrogen Peroxide and Ozone/UV Radiation for Reduction of Trihalomethane Formation Potential in Surface Water

Applied ozone dosages of 20, 25, and 30 mg/L to lake water utilized by the city of Shreveport, LA produced no significant reductions in trihalomethane formation potentials (THMFP). However, the addition of 20 mg/L of hydrogen peroxide and/or 0.67 W/L of UV radiation (254 nm) in combination with ozone produced decreases in THMFP of over 60% in 60 minutes. Smaller THMFP decreases were seen with shorter contact times. The use of H₂O₂ and/or UV in combination with O₃ increased the percentage of applied ozone consumed by the lake water (i.e., enhanced the ozone mass transfer) five times over simple ozonation.     

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.     

Ozone is the most effective disinfectant for dental treatment units: Results after 8 years of comparison

The method of disinfecting water in dental treatment units using ozone‐containing water was first described 10 years ago. In an investigational period over the last 8 years, waters from the outlets of 14 treatment units were examined microbiologically in a total of 240 tests. Twelve of the treatment units, employing hydrogen peroxide/silver ion disinfection ‐ after repeated sanitization ‐ regularly exceeded the limits laid down in the regulations governing water purity, and Pseudomonas aeruginosa could be detected at 181 water outlets. However, germs could hardly be detected in any of the tests of waters sampled from the two treatment units using ozonated water disinfection.     

Water Disinfection of Dental Units using Ozone – Microbiological Results after 11 Years and Technical Problems

Water disinfection in dental treatment units using ozone and hydrogen peroxide/silver ion were compared for a period of 11 years. Water from nine treatment units was microbiologically examined in a total of 240 tests. Eight treatment units using peroxide disinfection regularly exceeded the limits stipulated by water purity regulations, and Pseudomonas aeruginosa was detected at 154 water outlets. However, hardly any of the water specimens taken from the treatment unit using ozonated water disinfection showed bacteria. Four technical problems to using ozonated water were found during this eleven year period. The use of hydrogen peroxide necessitated 48 basic disinfections.     

Application of Combined Ozone–Hydrogen Peroxide for the Removal of Aromatic Compounds from a Groundwater

Nitro and chlorobenzene compounds, which are widely used in dye industries, have been associated recently with groundwater contamination. Because of their potential toxicity and for taste and odor considerations, three main actions were undertaken to solve the problem. First, to follow the advance of pollution toward the wells, samples were collected automatically and analyzed using GC-MS. Results indicate that o-chloronitrobenzene was the main pollutant in concentrations ranging from 10 to 2000μg/L. Second, to monitor the drinking water quality, an on-line spectrophotometer was used to measure the optical density at 254 nm at the inlet and outlet of the plant. Third, the feasibility of using the O₃/H₂O₉ combination was determined at a 450 L/h pilot plant. Reduction of concentrations of chloronitrobenzenes from 1900 μ/L to less than 20 μg/L could be reached by the application of 8 mg O3/L and 3 mg H2O9/L with a 20-minute contact time. To avoid an eventual bacterial egrowfn in the network due to biodegradability of the oxidation by-products, sand and GAC filtration were tested after oxidation. An evaluation of the costs of these different treatments is also presented.     

Kinetics of Estrone Ozone/Hydrogen Peroxide Advanced Oxidation Treatment

Ozone/hydrogen peroxide batch treatment was utilized to study the degradation of the steroidal hormone estrone (E1). The competition kinetics method was used to determine the rate constants of reaction for direct ozone and E1, and for hydroxyl radicals and E1 at three pH levels (4, 7, and 8.5), three different molar O₃/H₂O₂ ratios (1:2, 2:1, and 4:1) and a temperature about 20°C. The average second-order rate constants for direct ozone-E1 reaction were determined as 6.2?×?10³?±?3.2?×?10³ M^?1s^?1, 9.4?×?10⁵?±?2.7?×?10⁵ M^?1s^?1, and 2.1?×?10⁷?±?3.1?×?10⁶ M^?1s^?1 at pH 4, 7, and 8.5, respectively. It was found that pH had the greatest influence on the reaction rate, whereas O₃/H₂O₂ ratio was found to be slightly statistically significant. For the hydroxyl radical-E1 reaction, apparent rate constants ranged from 1.1?×?10¹⁰ M^?1s^?1 to 7.0?×?10¹⁰ M^?1s^?1 with an average value of 2.6?×?10¹⁰ M^?1s^?1. Overall, O₃/H₂O₂ is shown to be an effective treatment for E1.     

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.     

Ozone in oral surgery ‐ current status and prospects

Ozone has proved to be an effective water disinfectant for dental treatment units. Using this technique it is now possible to keep the water in a dental treatment unit low in germ count or germ‐free. Growth of germs does not occur during the routine intermissions in the daily activities of a dental office. Since ozonated water is germ‐free, it can be used in dental surgery as a coolant for burrs and for rinsing wounds. Thus, properties of ozone relevant to medicine can be utilized in the field of dental, oral and maxillomandibular surgery.     

Use of Ozonated Water for Disinfecting Gastrointestinal Endoscopes

The reprocessing of endoscopes is a complex procedure due to their structural design. In the constant search for new antimicrobial substances, recent studies with ozone have yielded great benefits. The present study evaluated the effects of ozonated water used to disinfect endoscopes comparing its efficacy with the conventional technique (2% glutaraldehyde). According to the results obtained, when ozonated water was used (330 mg.min.L^?1), induced a 2 log reduction of the viable microorganisms under the conditions tested. Ozonated water was a potent gastrointestinal endoscopic sanitizer, suggesting it is a feasible alternative for disinfection.     

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.     

Treatment of Industrial Landfill Leachates By Chemical And Biological Methods: Ozonation,Ozonation + Hydrogen Peroxide,Hydrogen Peroxide And Biological Post-Treatment For Ozonated Water

The objective of this study was to determine a suitable treatment method for variable waters from a forest industry landfill site. The main target was to find out the impact of different chemical treatments on the composition and biodegradability of those waters. Earlier studies have shown that biological treatment alone is not a suitable treatment method for these waters. That is why ozonation, ozonation+hydrogen peroxide and hydrogen peroxide treatment were studied in a laboratory scale. The ozonated waters were also biologically post-treated.

All the methods studied were able to degrade a part of the organic compounds and convert them into a more biodegradable form. Also the BOD/COD -ratio increased significantly. The removal of organic compounds by ozonation was 30 - 50 %. Hydrogen peroxide addition did not improve the degradation. The combination of pre-ozonation and biological post-treatment gave a total TOC removal between 50 - 95 %.     

The Basic Principles of UV–Disinfection of Water

The disadvantage of chlorination of drinking water is the possible synthesis of toxic chlorinated fragments. In different cases UV can be an alternative to chlorination. The germicidal effectiveness of UV–radiation is in the 180–320 nm region with an optimum at 265 nm. Approximately 95% of the energy radiated by a low–pressure mercury arc is at the 253.7 nm line, so this source is the most effective one for germicidal applications. The germicidal effectiveness of a broadband source can be calculated. UV alone cannot decrease the concentrations of organic contaminants of the treated water. Quite promising are the systems where UV–radiation acts as a catalyst in oxidation reactions in order to decrease the organic contaminants.     

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.     

Influence of Carbonate on the Ozone/Hydrogen Peroxide Based Advanced Oxidation Process for Drinking Water Treatment

The influence of carbonate on the ozone/hydrogen peroxide process has been investigated. Carbonate radicals, which are formed from the reaction of bicarbonate/carbonate with OH radicals, act as a chain carrier for ozone decomposition due to their reaction with hydrogen peroxide. The efficiency of bicarbonate/carbonate as a promoter for the radical-based chain reaction in presence of hydrogen peroxide has been calibrated and compared to a well-known chain promoter (methanol) and an inhibitor (tert-butanol). Relative to tert-butanol, the hydrogen peroxide induced ozone decomposition is accelerated by bicarbonate/carbonate. Relative to methanol, bicarbonate/carbonate in presence of hydrogen peroxide is less effective as a promoter under comparable experimental conditions.     

The influence of the water heater in dental chairs on the ozone concentration in the water used

Water heaters in dental chairs serve to heat water to about body temperature in order to make it more comfortable for the patient. This leads to a reduction in ozone concentration of 40–50%, as shown in laboratory experiments and also at dental chairs. In the event that evidence is found of positive biological effects in oral surgery on using relatively high ozone concentrations in water (5–10 μg/ml) then water heaters should not be used.     

Water Oxidation By Ozone Or Ozone/Hydrogen Peroxide Using The “Ozotest” Or “Peroxotest” Methods

This article presents a simple, rapid and efficient laboratory method permittingone to simulate the effects of ozonation (OZOTEST method) or of an oxidation by combined ozone/hydrogen peroxide (PEROXOTEST method) on an industrialscale. A critical analysis of the method is made (ozone transfer, validity of the results) and several practical applications are submitted for consideration (ozone demand, oxidation of atrazine and the DOC).     

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.     

Effects of Ozone and Ozone/Hydrogen Peroxide on the Degradation of Model and Real Oil-Sands-Process-Affected-Water Naphthenic Acids

Naphthenic acids (NAs) are persistent compounds that contribute to the toxicity of oil sands process-affected water (OSPW). In this study, the effects of ozone and ozone/hydrogen peroxide on the NAs degradation in buffered water and OSPW were examined. Cyclohexanoic acid (CHA) was used as a model NAs compound in buffered water experiments at two different pHs, using radical scavengers. At pH 9, the addition of carbonate did not have any effect on CHA degradation. Additions of tert-butyl alcohol and tetranitromethane decreased the CHA degradation levels. For the OSPW experiments, degradation of acid-extractable fraction (AEF) and NAs was examined. Approximately 90% of AEF was oxidized in a semi-batch system. In a batch system, 99% of OSPW NAs were degraded. This study demonstrated that ozone and ozone/hydrogen peroxide could be suitable treatment processes for OSPW remediation.     

Enhanced Bactericidal Effect of O3/H2O2 Followed by Cl2

With the appearance of chlorine resistant microorganisms such as Cryptosporidium parvum and Giardia lamblia in drinking water, significant attention has been drawn to the sequential application of multiple disinfectants including ozone, chlorine dioxide, and UV as a primary disinfectant. However, few studies have reported about the inactivation behavior of ozone-based AOP (advanced oxidation process) or its sequential application combined with other disinfectants. This is especially important since ozone itself experiences difficulty in the inactivation of these pathogens, especially at low temperatures: This study investigates the enhanced inactivation of Bacillus subtilis spores by the presence of an OH radical in the O₃/H₂O₂ system and the synergistically enhanced inactivation in the application of the O₃/H₂O₂ system followed by Cl₂. The results suggest that the O₃/H₂O₂ process can be considered as one of the viable alternatives when O₃ alone does not satisfy the disinfection requirement.     

Effect of Application of Ozone and Ozone Combined with Hydrogen Peroxide and Titanium Dioxide in the Removal of Pesticides From Water

The aim of this research work is to study the influence of hydrogen peroxide and titanium dioxide in the ozone-based treatment to degrade 44 organic pesticides present in natural water, which are systematically detected in the Ebro River Basin (Spain). The studied pesticides are: alachlor, aldrin, ametryn, atrazine, chlorfenvinfos, chlorpyrifos, pp'-DDD, op'-DDE, op'-DDT. pp'-DDT, desethylatrazine, 3,4-dichloroaniline, 4,4'-dichlorobenzophenone, dicofol, dieldrin, dimethoate, diuron, α-endosulphan, endosulphan-sulphate, endrin, α-HCH, β-HCH, γ-HCH, δ-HCH, heptachlor, heptachlor epoxide A, heptachlor epoxide B, hexachlorobenzene, isodrin, 4-isopropylaniline, isoproturon, metholachlor, methoxychlor, molinate, parathion methyl, parathion ethyl, prometon, prometryn, propazine, simazine, terbuthylazine, terbutryn, tetradifon and trifluralin. The ozonation using 3 mg O₃ L^?1 produces a pesticides removal close to 23%, whereas the application of O₃/H₂O₂ and O₃/TiO₂ treatments achieves average degradation yields lower than the ozonation. However, the application of O₃/H₂O₂ /TiO₂ process improves considerably the pesticides degradation and an average degradation yield of 36% is obtained.