Ozone-based Advanced Oxidation Processes Research Articles

The oxidation study of 2-propanol using ozone-based advanced oxidation processes

In the present study, advanced oxidation processes (AOPs) have been successfully used to decompose isopropyl alcohol (IPA). IPA degradation and its major degradation intermediate, acetone formation and total organic carbon (TOC) removal efficiency were studied using O 3, O 3/UV, H 2O 2/UV, H 2O 2/O 3, and H 2O 2/O 3/UV processes at various physico-chemical conditions. Complete degradation of IPA was noted in AOPs whereas complete acetone decomposition was not observed under the experimental conditions. Ozonation process was strongly enhanced in the presence of UV light, H 2O 2 or in the presence of both oxidants. Ozonation process in the presence of UV light enhancement about 11%, 15%, 28% of IPA decomposition and 20%, 23%, 0% of TOC removal was observed at pH 3, 7, and 10. Similarly, in the presence of H 2O 2 (0.25 g/g) further enhancement of 31%, 50%, 18% of IPA degradation and 26%, 30%, 27% of TOC removal at 180 min was noted at pH 3, 7, and 10, respectively. UV/H 2O 2 process was found to be the least efficient and UV/H 2O 2/O 3 was the most efficient process compared to all other selected AOPs. Acetone was identified as a primary degradation intermediate and subsequently acetic acid, formic acid, and oxalic acid were identified as secondary intermediates. It was concluded that ozone-based AOPs were efficient for IPA degradation in wastewater.

Treatment of Industrial Cork Processing Water by Ozonation and Ozone Based Advanced Oxidation Processes (O3/UV and O3/H2O2) in a Bubble Column Reactor

AbstractThe treatment of industrial cork-processing water at natural pH (6.45) by ozonation alone and ozone based advanced oxidation processes (O

Successful Application of a High-Performance Ozone-Based Advanced Oxidation Process (AOP) for Remediation of Heavily Contaminated Groundwater

Successful Application of a High-Performance Ozone-Based Advanced Oxidation Process (AOP) for Remediation of Heavily Contaminated Groundwater

Ozone-Based Advanced Oxidation Processes for the Decomposition of N-Methyl-2-Pyrolidone in Aqueous Medium

The present study investigates the decomposition of N-Methyl-2-Pyrolidone (NMP) using conventional ozonation (O3), ozonation in the presence of UV light (UV/O3), hydrogen peroxide (O3/H2O2), and UV/H2O2 processes under various experimental conditions. The influence of solution pH, ozone gas flow dosage, and H2O2 dosage on the degradation of NMP was studied. All ozone-based advanced oxidation processes (AOPs) were efficient in alkaline medium, whereas the UV/H2O2 process was efficient in acidic medium. Increasing ozone gas flow dosage would accelerate the degradation of NMP up to certain level beyond which no positive effect was observed in ozonation as well as UV light enhanced ozonation processes. Hydrogen peroxide dosage strongly influenced the degradation of NMP and a hydrogen peroxide dosage of 0.75 g/L and 0.5 g/L was found to be the optimum dosage in UV/H2O2 and O3/H2O2 processes, respectively. The UV/O3 process was most efficient in TOC removal. Overall it can be concluded that ozonation and ozone-based AOPs are promising processes for an efficient removal of NMP in wastewater.

Degradation of Endocrine Disrupting Chemicals by Ozone/AOPs

The presence of endocrine-disrupting compounds (EDCs) in the aqueous environment is of increasing concern due to their adverse impact on aquatic life, and potential risk to human health. Among the EDCs of concern are steroidal estrogenic hormones such as estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2), which have a high environmental prevalence and strong estrogenic activity. In addition, the extensive use of alkylphenol ethoxylates (APnEOs), bisphenol A (BPA) and phthalate compounds have resulted in an environmental presence at significant concentrations, although they appear to have a lower estrogenic activity than the steroidal hormones. As water and wastewaters are some of the primary routes of exposure to EDCs, it is important to determine at what levels EDCs are found in these media and how these levels may be reduced. Hence, it is necessary to understand the fate of EDCs in conventional water and wastewater treatment plants, as well as the efficacy of more specialized treatment methods, such as adsorption and oxidation. This paper is a summary of the latest information on the degradation of prominent EDCs by ozone and ozone-based advanced oxidation processes (AOPs). From this review, it is clear that ozone and AOPs are effective in degrading these EDCs, with the possible exception of phthalates, which are relatively stable to ozone oxidation. Knowledge of the formation of reaction products from the treatment by ozone and AOPs is relatively poor at present, and particularly for the non-steroid compounds.

Degradation of DMSO by ozone-based advanced oxidation processes

The present study investigates the oxidation of dimethyl sulfoxide (DMSO) by conventional ozonation and the advanced oxidation processes (AOPs). The major degradation products identified were methanesulfinate, methanesulfonate, formaldehyde, and formic acid in ozonation process. The subsequent degradation of intermediates shows that methanesulfonate is more resistance to ozonation, which reduces the mineralization rate of DMSO. The effect of t-butanol addition and ozone gas flow dosage on the degradation rate was evaluated. The rate constant of the reaction of ozone ( k D) with DMSO was found to be 0.4162 M −1 S −1. In the second part of this study, DMSO degradation and TOC mineralization were investigated using O 3/UV, O 3/H 2O 2 and UV/H 2O 2 processes. In all theses processes the degradation of target organics is more pronounced than TOC removal. The efficiencies of these processes were evaluated and discussed. The formation of sulfate ion in all AOPs have been identified and compared with other processes. Overall it can be concluded that ozonation and ozone-based AOPs are promising processes for an efficient removal of DMSO in wastewater.

Comparison of the efficiency of [rad]OH radical formation during ozonation and the advanced oxidation processes O 3/H 2O 2 and UV/H 2O 2

Comparison of advanced oxidation processes (AOPs) can be difficult due to physical and chemical differences in the fundamental processes used to produce OH radicals. This study compares the ability of several AOPs, including ozone, ozone+H 2O 2, low pressure UV (LP)+H 2O 2, and medium pressure UV (MP)+H 2O 2 in terms of energy required to produce OH radicals. Bench scale OH radical formation data was generated for each AOP using para-chlorobenzoic acid (pCBA) as an OH radical probe compound in three waters, Lake Greifensee water, Lake Zurich water, and a simulated groundwater. Ozone-based AOPs were found to be more energy efficient than the UV/H 2O 2 process at all H 2O 2 levels, and the addition of H 2O 2 in equimolar concentration resulted in 35% greater energy consumption over the ozone only process. Interestingly, the relatively high UV/AOP operational costs were due almost exclusively to the cost of hydrogen peroxide while the UV portion of the UV/AOP process typically accounted for less than 10 percent of the UV/AOP cost and was always less than the ozone energy cost. As the OH radical exposure increased, the energy gap between UV/H 2O 2 AOP and ozone processes decreased, becoming negligible in some water quality scenarios.

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.

Measurement of the initial phase of ozone decomposition in water and wastewater by means of a continuous quench-flow system: Application to disinfection and pharmaceutical oxidation

Due to a lack of adequate experimental techniques, the kinetics of the first 20 s of ozone decomposition in natural water and wastewater is still poorly understood. Introducing a continuous quench-flow system (CQFS), measurements starting 350 ms after ozone addition are presented for the first time. Very high HO to O 3 exposures ratios ( R ct=∫HO d t/∫O 3d t) reveal that the first 20 s of ozonation present oxidation conditions that are similar to ozone-based advanced oxidation processes (AOP). The oxidation of carbamazepine could be accurately modeled using O 3 and HO exposures measured with CQFS during wastewater ozonation. These results demonstrate the applicability of bench scale determined second-order rate constants for wastewater ozonation. Important degrees of pharmaceutical oxidation and microbial inactivation are predicted, indicating that a significant oxidation potential is available during wastewater ozonation, even when ozone is entirely decomposed in the first 20 s.

Aqueous Pesticide Degradation by Ozonation and Ozone-Based Advanced Oxidation Processes: A Review (Part II)

Pesticides are known to be persistent in surface water and groundwater supplies and as a result, their existence in these water sources has been recognized as a major problem in many countries. The occurrence of these persistent pesticides in water bodies can also cause potential adverse public and environmental health effects. Among many water and wastewater treatment options, ozonation and ozone-based advanced oxidation processes, such as ozone/hydrogen peroxide, ozone/ultraviolet irradiation, and ozone/hydrogen peroxide/ultraviolet irradiation, possess a high potential for degrading and detoxifying these pollutants in water and wastewater. In this paper, ozone based treatment of four major groups of pesticides, namely aniline-based compounds, pyridines and pyrimidines, triazines, and substituted ureas, as well as that of several miscellaneous pesticides are reviewed. Degree of pesticide degradation, reaction kinetics, identity and characteristics of degradation by-products, and possible degradation pathways are covered and discussed.

Aqueous Pesticide Degradation by Ozonation and Ozone-Based Advanced Oxidation Processes: A Review (Part I)

Pesticide pollution of surface water and groundwater has been recognized as a major problem in many countries because of their persistence in aquatic environment and potential adverse health effects. Among various water and wastewater treatment options, ozonation and ozone-based advanced oxidation processes, such as ozone/hydrogen peroxide, ozone/ultraviolet irradiation, and ozone/hydrogen peroxide/ultraviolet irradiation, are likely key technologies for degrading and detoxifying these pollutants in water and wastewater. In this paper, ozone-based treatment of four major groups of pesticides, namely carbamates, chlorophenoxy compounds, organochlorines, and organophosphates, are reviewed. Degree of pesticide degradation, reaction kinetics, identity and characteristics of degradation by-products and intermediates, and possible degradation pathways are covered and discussed.

Treatment of landfill leachate by ozone-based advanced oxidation processes

In this study, laboratory experiments are conducted to compare the efficacy using several ozone-based advanced oxidation processes (AOPs), such as O 3, O 3/H 2O 2, and O 3/UV, to treat landfill leachate. Raw leachate was initially coagulated by ferric chloride (FeCl 3) at the experimental-determined optimal dosage of 900 mg l −1, and the ozone-based AOPs were subsequently applied. Results indicate that all AOPs would result in a significant increase on the ratio of BOD 5/COD from 0.06 to 0.5 at the applied ozone dosage of 1.2 g l −1. The increase on biodegradability for ozonated leachate indicates that these AOPs would be beneficial to the subsequent biological treatment process. To better explain the alteration of high organic molecules after oxidation, ultrafiltration was used to separate the leachate by several molecular weight cutoffs (MWCO). The COD distribution for coagulated leachate is 34% for MWCO > 10 kDa, 7% for MWCO between 5 and 10 kDa, 22% for MWCO between 1 and 5 kDa, and 37% for MWCO < 1 kDa. Following ozonation or AOPs, the predominant distribution of COD would be obviously shifted to the MWCO less than 1000 g mol −1 (72–85%) over the other MWCO ranges. In addition, Gel Permeation Chromatograph (GPC) analysis has showed a substantial agreement on the cleavage of larger organic compounds into smaller ones. O 3/UV was found to be the most effective approach among these ozone-based AOPs to enhancing the biodegradability and eliminating the color of leachate.

Advanced Oxidation of Bromide-Containing Waters: Bromate Formation Mechanisms

Bromate formation in ozone-based advanced oxidation processes (AOPs) was investigated by laboratory experiments in combination with kinetic modeling. Oxidant concentrations were monitored during the experiments, which allows us to account for the relative contributions of ozone and OH radical pathways. It has been shown by gamma-irradiation of bromide-containing solutions in the pH range 6-8 that bromate can be formed by a pure OH radical mechanism and that hypobromous acid/hypobromite (HOBr/ OBr-) is a requisite intermediate in bromate formation. The presence of hydrogen peroxide (H2O2), as in H2O2-based AOPs, leads to a reduction of HOBr/OBr- and therefore becomes a key reaction for the control of bromate formation. The steady-state concentration of OH radicals in AOPs is usually not high enough to compensate for this reduction reaction. Therefore, in gamma-irradiation experiments, no bromate was formed in the presence of H2O2 because OH radicals were the only possible oxidants to further oxidize HOBr/OBr-. However, in ozone-based AOPs at pH 7, where ozone is present in combination with H2O2, bromate was still formed. This was attributed to the oxidation of Br-. by O-3, which was investigated at pH 7. Our experimental findings could be best explained by a corresponding second-order rate constant k = 1.5 x 10(8) M-1 s(-1).