Ozone-based Advanced Oxidation Processes Research Articles

Ozonation of the algaecide irgarol: Kinetics, transformation products, and toxicity

The degradation of irgarol, a frequently detected algaecide in the aquatic environment, by ozonation was investigated in this study. The second-order rate constants for the reaction of irgarol with ozone (O3) and hydroxyl radical (OH) were determined to be 505 M−1 s−1 and 4.96 × 109 M−1 s−1, respectively. During ozonation, sixteen transformation products (TPs) of irgarol were proposed using an electrospray ionization quadrupole time-of-flight mass spectrometer. Most of the TPs are ozone-refractory compounds and therefore could only be further transformed by oxidation with OH generated from O3 decomposition during ozonation. Toxicity analysis using the ecological structure activity relationship class program indicates that some of the TPs (e.g., irgarol sulfoxide) still exhibit high acute or chronic toxicity to aquatic organisms (fish, daphnia, and algae) as the parent compound. With a typical ozone dose applied in water treatment (2 mg/L, corresponding to a specific ozone dose of 0.8 mg O3/mg dissolved organic carbon), irgarol could be completely abated in a selected surface water by ozonation. However, most of the TPs persisted in the ozonation effluent because of their low ozone reactivity. The results of this study suggest that ozonation with typical ozone doses applied in water treatment may not be able to sufficiently reduce the ecotoxicological effects of irgarol on aquatic organisms. More effective treatment processes such as ozone-based advanced oxidation processes may be required to enhance the removal of toxic TPs of irgarol in water treatment.

Oxidation of emerging biocides and antibiotics in wastewater by ozonation and the electro-peroxone process

This study investigated the abatement of a number of antimicrobials frequently detected in municipal wastewater by conventional ozonation and a recently developed ozone-based advanced oxidation process, the electro-peroxone (E-peroxone) process. A synthetic water and a real secondary wastewater effluent were spiked with fourteen antimicrobials, including antibiotics and biocides, and then treated by the two processes. The results show that most of the antibiotics investigated (e.g., ofloxacin, trimethoprim, norfloxacin, and ciprofloxacin) readily react with ozone (O3) and could therefore be efficiently eliminated from the water matrices by direct O3 oxidation during both processes. In contrast, most of the biocides tested in this study (e.g., clotrimazole, pentamidine, bixafen, propiconazole, and fluconazole) were only moderately reactive, or non-reactive, with O3. Therefore, these biocides were removed at considerably lower rate than the antibiotics during the two ozone-based processes, with hydroxyl radical (OH) oxidation playing an important role in their abatement mechanisms. When compared with conventional ozonation, the E-peroxone process is defined by the in situ electrogeneration of hydrogen peroxide, which considerably enhances the transformation of O3 to OH. As a result, the E-peroxone process significantly accelerated the abatement of biocides and required a considerably shorter treatment time to eliminate all of the tested compounds from the water matrices than conventional ozonation. In addition, the E-peroxone process enhanced the contributions of OH fractions to the abatement of moderately ozone reactive benzotriazoles. These results demonstrate that the E-peroxone process holds promise as an effective tertiary treatment option for enhancing the abatement of ozone-resistant antimicrobials in wastewater.

Oxidation of Trace Organic Contaminants (TrOCs) in Wastewater Effluent with Different Ozone-Based AOPs: Comparison of Ozone Exposure and •OH Formation

Ozone-based advanced oxidation processes (AOPs), recognized as effective methods for tertiary water treatment in view of trace organic contaminant (TrOC) removal, were investigated in this study. B...

Ozone-Based Advanced Oxidation Processes for Primidone Removal in Water using Simulated Solar Radiation and TiO2 or WO3 as Photocatalyst.

In this work, primidone, a high persistent pharmacological drug typically found in urban wastewaters, was degraded by different ozone combined AOPs using TiO2 P25 and commercial WO3 as photocatalyst. The comparison of processes, kinetics, nature of transformation products, and ecotoxicity of treated water samples, as well as the influence of the water matrix (ultrapure water or a secondary effluent), is presented and discussed. In presence of ozone, primidone is rapidly eliminated, with hydroxyl radicals being the main species involved. TiO2 was the most active catalyst regardless of the water matrix and the type of solar (global or visible) radiation applied. The synergy between ozone and photocatalysis (photocatalytic ozonation) for TOC removal was more evident at low O3 doses. In spite of having a lower band gap than TiO2 P25, WO3 did not bring any beneficial effects compared to TiO2 P25 regarding PRM and TOC removal. Based on the transformation products identified during ozonation and photocatalytic ozonation of primidone (hydroxyprimidone, phenyl-ethyl-malonamide, and 5-ethyldihydropirimidine-4,6(1H,5H)-dione), a degradation pathway is proposed. The application of the different processes resulted in an environmentally safe effluent for Daphnia magna.

Effects of coexisting substances on aniline degradation with ozone-based advanced oxidation process in high-gravity fields

Effects of common coexisting substances in industrial wastewater on the removal of total organic carbon (TOC) by O3/Fe(II) and O3/Fenton systems in rotating packed bed (RPB) were investigated. The results show that for the RPB-O3/Fe(II) system, Na3PO4 and NaNO3 act as a promoter for the removal of TOC in aniline-containing wastewater; NaOH, Na2CO3, NaNO2, NaCl and NaHCO3 act as an inhibitor for the removal of TOC. For the RPB-O3/Fenton system, NaNO3, NaOH, and Na3PO4 can promote the removal of TOC and follows the order of Na3PO4 > NaNO3 > NaOH; NaCl and NaNO2 can inhibit the removal of TOC and follows the order of NaCl > NaNO2; Na2CO3 and NaHCO3 can have a promoting effect on the removal of TOC at a low concentration, but an inhibitory effect at a high concentration. The wastewater pH and ·OH production play a critical role in promoting or inhibiting the removal of TOC by RPB-O3/Fe(II) and RPB-O3/Fenton systems. However, it is important to note that the promoting/inhibitory effects on the RPB-O3/Fenton system are lower than that on the RPB-O3/Fe(II) system, indicating that RPB-O3/Fenton system may be more applicable to the treatment of industrial aniline-containing wastewater.

Treatment of highly polluted industrial wastewater by means of sequential aerobic biological oxidation-ozone based AOPs

The feasibility of the treatment of a complex industrial wastewater by aerobic biodegradation in a sequential batch reactor (SBR) followed by ozone-based advanced oxidation processes (AOPs) has been studied. The industrial wastewater had high organic load (TOC > 3 g L−1, COD > 12 g L−1, BOD5 > 2 g L−1) including some toxic/harmful compounds and high concentration of metal and other inorganic species. SBR treatment of the industrial wastewater diluted with urban wastewater (dilution 1:5), was successful after complete acclimation of the mixed culture (i.e., >50% COD and TOC removals). Nevertheless, the SBR effluent was still not acceptable to be disposed into the environment (c.a. COD 850 mg L−1) so ozonation, solar photo-ozonation and solar photocatalytic ozonation processes were investigated as further polishing treatments. Thus, the sequential combination of aerobic biodegradation and solar photocatalytic ozonation with a TiO2-based catalyst led to an effluent suitable for discharge into the aquatic environment according to environmental regulations (COD < 125 mg L−1, BOD5 < 25 mg L−1).

Enhanced mineralization of atrazine by surface induced hydroxyl radicals over light-weight granular mixed-quartz sands with ozone

A light-weight granular mixed-quartz sand (denoted as L-GQS) combined with stirring-assisted bubble column reactor was firstly applied in catalytic ozonation of atrazine. The L-GQS, with a density of 2.36 g cm−3 and average diameter of ca. of 4 mm, was readily churned up and uniformly distributed within the solution in the reactor. The introduction of L-GQS was found to exhibit enhanced catalytic ozonation of atrazine, with the increase in degradation rate and the dissolved organic carbon (DOC) removal being more than 2-fold for the catalytic process (L-GQS dosage = 5 g L−1, [atrazine]0 = 50 μM, [O3] = 25 mg L−1, gas flow = 0.2 L min−1, at pH 7.0 and 293 K). The L-GQS settled at the bottom of the reactor after experimentation, allowing its easy separation from the solution. A complete characterization of the material (XRD, XPS, FTIR, FE-SEM/EDS, BET and pHpzc) revealed that L-GQS consisted of α-quartz, β-cristobalite, anorthoclase and small amount of iron oxy-hydroxides. Hydroxyl groups, Bronsted acid sites and Lewis acid sites on the surface of L-GQS all contributed to the atrazine adsorption, ozone decomposition and ·OH generation. The L-GQS catalyzed ozonation exhibited superior atrazine degradation and mineralization rates in a wide range of pH (3.0–9.0) and reaction temperatures (278 K–293 K). Also, an enhancement of DOC abatement was observed both in presence of natural organic matter isolates and natural water matrices (river water) when L-GQS was used. Finally, the degradation mechanism was proposed, based on the intermediates and by-products formation analyzed by LC-QTOF-MS/MS and ionic chromatography. Our results indicate that the L-GQS combined with stirring-assisted bubble column reactor could be utilized as an enhancement of ozone-based advanced oxidation processes.

Decomplexation of electroplating wastewater by ozone-based advanced oxidation process.

Heavy metal contamination from electroplating wastewater is a serious risk to terrestrial life and public health. The complexed metal cannot be effectively removed by traditional precipitation without decomplexing. In this work, four ozone-based advanced oxidation processes, O3, O3/H2O2, O3/UV and O3/H2O2/UV to decomplex electroplating wastewater were investigated and their performance compared. Ethylenediaminetetraacetic acid (EDTA) and citric acid are the most common components of electroplating wastewater. They were used as representatives to study the decomplexation and mineralization of complexes in the ozone-based advanced oxidation processes. Among all, the highest degradation and mineralization efficiency of EDTA occurred in O3/UV and was 65% and 53% in 60 min, respectively. For citric acid, the highest degradation (77%) and mineralization (56%) efficiency was observed in the O3/H2O2/UV process. This indicates that selection of the advanced oxidation process is determined by the target contaminant.

Degradation of bisphenol A by combining ozone with UV and H2O2 in aqueous solutions: mechanism and optimization

A laboratory-scale study on the abatement of bisphenol A (BPA) was performed by combining O3 with H2O2 and UV (O3/H2O2/UV), an ozone-based advanced oxidation processes technique (AOP). This work aimed to (1) evaluate the removal of BPA with O3/H2O2/UV, and to compare the degradation efficiency with other ozone-based AOPs (such as O3 alone, O3/H2O2, and O3/UV), (2) structurally optimize BPA abatement by using a central composite design (CCD) for experimental design purposes and/or a response surface methodology to find the optimum, and (3) identify the degradation pathways, and main intermediate products, formed during BPA abatement with O3/H2O2/UV. The degradation pathways of BPA degradation were revealed by O3/H2O2/UV on the basis of evidences of intermediate generation. The effect of initial pH, ozone, and H2O2 dose during BPA abatement was studied in detail. By increasing each of these three parameters, an enhancement of the BPA degradation efficiency is mostly observed. BPA can be degraded completely when a sufficiently high ozone dose is applied. However, excess H2O2, as a scavenger of HO·, has a negative effect on BPA abatement, resulting in a decrease in the BPA’s degradation efficiency. For example, the removal decreased from 64 to 58% by enhancing the H2O2 initial dose from 0.5 to 0.75 mmol/L (at an initial pH and ozone dose of, respectively, 7 and 0.1 mg/L). The results confirmed that combining ozone with H2O2 and UV was a more efficient method than the other three ozone-based AOPs on the removal of BPA. Therefore, this method could be further applied for the treatment of real wastewaters containing BPA and other micropollutants.

Effective method of treatment of industrial effluents under basic pH conditions using acoustic cavitation – A comprehensive comparison with hydrodynamic cavitation processes

The use of acoustic cavitation in advanced oxidation processes (AOPs) is a promising trend in research for treatment of industrial effluents. The paper presents the results of investigations on the use of acoustic cavitation aided by additional oxidation processes (ozonation/H2O2 oxidation/Peroxone/UV-C) for the treatment of effluents from the production of bitumens. Under these conditions, the total contaminant load, expressed as chemical oxygen demand (COD), could be lowered by 51%. In addition, changes in concentrations of volatile organic compounds identified in the effluents following the treatment are discussed. The investigations revealed that by using acoustic cavitation combined with the Peroxone process, the majority of oxygenated organic compounds were oxidized. The paper also compares AOPs based on acoustic cavitation with hydrodynamic cavitation-aided processes. This study revealed that the use of acoustic cavitation results in a higher effectiveness of degradation of organic compounds using AOPs based on hydrogen peroxide. On the other hand, hydrodynamic cavitation is generally a slightly more effective method for degradation of organic compounds for ozone-based AOPs. Furthermore, furfural and 2-methylcyclohexanone were discovered as secondary pollutants whose concentration increased during the treatment.

Pilot-scale evaluation of micropollutant abatements by conventional ozonation, UV/O3, and an electro-peroxone process

The electro-peroxone (E-peroxone) process is an emerging ozone-based advanced oxidation process (AOP) that has shown large potential for micropollutant abatement in water treatment. To evaluate its performance under more realistic conditions of water treatment, a continuous-flow pilot E-peroxone system was developed and compared with conventional ozonation and a UV/O3 process for micropollutant abatements in various water matrices (groundwater, surface water, and secondary wastewater effluent) in this study. With a specific ozone dose of 1.5 mg O3/mg DOC, micropollutants that have high and moderate reactivity with ozone (O3) (diclofenac, naproxen, gemfibrozil, and bezafibrate) could be sufficiently abated (>90% abatement) in the various waters by all three processes. However, ozone-resistant micropollutants (ibuprofen, clofibric acid, and chloramphenicol) were abated only by ∼32–68%, 68–91%, and 73–90% during conventional ozonation of the selected groundwater, surface water, and secondary wastewater effluent, respectively. By electro-generating H2O2 or applying UV irradiation to enhance O3 transformation to •OH during ozonation, the E-peroxone and UV/O3 processes similarly enhanced the abatement efficiencies of ozone-resistant micropollutants by ∼15–43%, ∼5–15%, and ∼5–10% in the groundwater, surface water, and secondary wastewater effluent, respectively. In addition, the E-peroxone and UV/O3 processes significantly reduced bromate formation during the treatment of the three waters compared to conventional ozonation. Due to its higher efficiency, the E-peroxone process reduced ∼10–53% of the energy consumption required to abate the concentration of chloramphenicol (the most ozone-resistant micropollutant spiked in the waters) by 1 order of magnitude in the three waters compared to conventional ozonation. In contrast, the UV/O3 process consumed approximately 4–10 times higher energy than conventional ozonation. This pilot-scale study demonstrates that the E-peroxone process can provide a feasible, effective, and energy-efficient alternative for micropollutant abatement and bromate control in water and wastewater treatment.

The removal of organic compounds from landfill leachate using ozone-based advanced oxidation processes

In this study, the application of ozonation and ozonation with hydrogen peroxide processes for landfill leachate treatment was investigated. The effluents were characterized by COD 710 mgO2/dm3 and BOD5 72 mg O2/dm3. According to the adopted indicators, the determined BOD/COD ratio of 0.1 in raw leachates indicates a stabilized landfill. Ozone was applied at doses of 0.15 - 0.6 gO3/dm3, and hydrogen peroxide at such doses to keep the weight ratios of H2O2/O3 0.4 - 1.6. The maximum COD and UV absorbance removal was respectively 29% and 51% by applying a high ozone dose of 0.6 gO3/dm3. After oxidation, the ratio of BOD/COD was increased from 0.1 up to 0.3. It has been shown that by using hydrogen peroxide in ozonation, organic compounds expressed as COD can be efficiently removed from the effluents. The best conditions for the H2O2/O3 process were obtained with a H2O2/O3 ratio of 0.8 and ozone dose of 0.6 gO3/dm3. Under these conditions, the removal efficiency of COD was 46%.

The removal of COD and NH3-N from atrazine production wastewater treatment using UV/O3: experimental investigation and kinetic modeling.

In this study, a UV/O3 hybrid advanced oxidation system was used to remove chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and atrazine (ATZ) from ATZ production wastewater. The removal of COD and NH3-N, under different UV and O3 conditions, was found to follow pseudo-first-order kinetics with rate constants ranging from 0.0001-0.0048 and 0.0015-0.0056min-1, respectively. The removal efficiency of ATZ was over 95% after 180min treatment, regardless the level of UV power. A kinetic model was further proposed to simulate the removal processes and to quantify the individual roles and contributions of photolysis, direct O3 oxidation, and hydroxyl radical (OH·) induced oxidation. The experimental and kinetic modeling results agreed reasonably well with deviations of 12.2 and 13.1% for the removal of COD and NH3-N, respectively. Photolysis contributed appreciably to the degradation of ATZ, while OH· played a dominant role for the removal of both COD and NH3-N, especially in alkaline environments. This study provides insights into the treatment of ATZ containing wastewater using UV/O3 and broadens the knowledge of kinetics of ozone-based advanced oxidation processes.

Removal of 1,4-Dioxane and Volatile Organic Compounds from Groundwater Using Ozone-Based Advanced Oxidation Process

ABSTRACTOzone and ozone/peroxide processes were evaluated for the removal of 1,4-dioxane from laboratory water and site groundwater. The effect of process parameters such as solution pH and dosage of peroxide was studied. Ozone alone was not very effective in removing 1,4-dioxane from water (≤ 20% removal). Enhanced oxidation of 1,4-dioxane was achieved by increasing the solution pH or by adding peroxide at neutral pH. Pseudo–first-order rate constants were calculated for the removal of 1,4-dioxane using ozone. Correlations were developed for the consumption of ozone per 1,4-dioxane removed. Acidic and neutral pH conditions resulted in higher consumption of ozone per dioxane removed. Basic solution pH and presence of hydrogen peroxide enhanced the dioxane removal, which resulted in lower consumption of ozone per dioxane removed. Following the lab study, ozonation was used for the remediation of site groundwater contaminated with 1,4-dioxane and chlorinated volatile organics. Presence of 5 mg/L of hydrogen peroxide during ozonation resulted in simultaneous removal of 1,4-dioxane and volatile organics from groundwater to target levels. For the AOP process, removal kinetics was approximately 50% slower in groundwater compared to the lab DI water.

Textile wastewater treatment by AOPs for brine reuse

Abstract The most contaminated textile wastewater stream, dyeing discharge with a high residual salt content, was selected to undergo dedicated treatment by advanced oxidation processes (AOPs). A simulated mixture, based on an industrial recipe and containing Reactive Yellow 145 (RY145), Reactive Red 195 (RR195), and Reactive Blue 221 (RB221), was investigated. These dyes are used together in the trichromatic technique in industrial dyeing, and they occur together in wastewater. In this study, for the first time, several ozone-based AOPs (O3, O3/H2O2, O3/UV and O3/UV/H2O2) were tested under comparable conditions and assessed. Moreover, the roles of hydrogen peroxide and UV during the AOPs were determined. The influence of textile auxiliaries on the AOPs was also investigated. Due to the usage of multiple dyes in the same mixture, colour was evaluated based on whole UV–vis spectra by recalculating them as integrals. Extremely fast decolourization of the textile wastewater was observed during ozonation. Only 10% colour remained after 10 min of treatment, and satisfactory mineralization was also achieved. During the AOP experiments, it was found that ozonation is the best treatment method for implementation in the industry. Textile wastewater treated by AOPs could be reused as a source of ‘ready to use’ brine for the next textile dyeing operation.

Ozone-based advanced oxidation process as pre-treatment of wastewater from the wood-based industry

Three ozone-based advanced oxidation treatments (O3; O3 with initial pH adjustment and; O3/UV with initial pH adjustment) were compared for the treatment of a recalcitrant wastewater generated during washing/cleaning of surfaces and equipment used in filling and gluing processes (urea-formaldehyde and phenol-formaldehyde resins) in a wood-floor industry in Sweden. The wastewater (initial COD 3,400-4,000 mg/L) was obtained at the outlet of a sedimentation tank, which receive an inflow with an average COD of 45,000 mg/L. The experiments were performed in a semi-batch microbubble column reactor connected to a UV reactor, where 2.5 L samples of wastewater were submitted to the maximum dose of 2 g of O3 per gram of initial COD. For the full-factorial design, the independent variables were O3 concentration (g O3/Nm3); recirculation flow (L/min); and initial pH (pHi). The evaluation of the treatment performance was based on COD and TOC reductions (in %), and the effluent obtained was used in respirometric assays with activated sludge obtained at a municipal wastewater treatment plant to assess biodegradability/inhibitory effects. The results showed that ozonation at the original low pH promoted a reduction of 65% and 31% of COD and TOC respectively, but made the effluent less biodegradable. The highest COD and TOC reductions were achieved when O3 /UV treatment with pHi = 9.3 were applied (93% e 56% reductions for COD and TOC respectively). The results with the respirometry tests suggest that application of O3 only at higher pH values promoted biodegradability enhancement of the effluent, making it treatable by microbiota obtained with activated sludge from a municipal wastewater treatment plant.

Mn2+/H2O2/O3, a high efficient advanced oxidation process in acidic solution

Mn2+/H2O2/O3, an ozone-based advanced oxidation process, was investigated in acidic solution. Acetic acid (HAc) was selected as the target compound to be degraded because it is often the final product of macromolecules degraded by chemical oxidation. The results showed that only Mn2+/H2O2/O3 could effectively remove acetic acid at initial pH 1.0, while others like O3, H2O2/O3, Mn2+/O3 and Mn2+/H2O2 almost had no removal ability, indicating that the coexistence of Mn2+, H2O2 and O3 was of great necessity to ensure the high removal rate of acetic acid in acidic solution. Optimized parameters suggested that there existed an optimal ratio of concentration of Mn2+ to concentration of H2O2 for acetic acid removal. The above results are of significance for effective treatment of acidic wastewater containing refractory pollutants. The mechanism study showed that Mn2+/H2O2/O3 in acidic solution was not associated with the generation of hydroxyl radicals, but with the generation of highly active intermediate Mn3+.

Ozone-based advanced oxidation processes for the removal of harmful algal bloom (HAB) toxins: a review

Ozone-based advanced oxidation processes for the removal of harmful algal bloom (HAB) toxins: a review

Advanced Oxidation Processes: Process Mechanisms, Affecting Parameters and Landfill Leachate Treatment.

Advanced oxidation processes (AOPs) are of special interest in treating landfill leachate as they are the most promising procedures to degrade recalcitrant compounds and improve the biodegradability of wastewater. This paper aims to refresh the information base of AOPs and to discover the research gaps of AOPs in landfill leachate treatment. A brief overview of mechanisms involving in AOPs including ozone-based AOPs, hydrogen peroxide-based AOPs and persulfate-based AOPs are presented, and the parameters affecting AOPs are elaborated. Particularly, the advancement of AOPs in landfill leachate treatment is compared and discussed. Landfill leachate characterization prior to method selection and method optimization prior to treatment are necessary, as the performance and practicability of AOPs are influenced by leachate matrixes and treatment cost. More studies concerning the scavenging effects of leachate matrixes towards AOPs, as well as the persulfate-based AOPs in landfill leachate treatment, are necessary in the future.

Comparison between industrial and simulated textile wastewater treatment by AOPs – Biodegradability, toxicity and cost assessment

Despite the fact that there are many literature reports concerning textile wastewater treatment by advanced oxidation processes (AOPs), mostly they are not oriented on the industrial applications. The research focused on Reactive Black 5 (RB5) and its industrial form (Setazol Black DPT), which, despite being hazardous, is still one of the most commonly used dyestuffs in industrial practice. Several ozone-based AOPs (e.g., O3, UV/O3, O3/H2O2, and O3/UV/H2O2) and H2O2/UV processes have been compared in terms of their effectiveness in removing RB5 (purified and commercial form) from simulated and industrial textile wastewater. The color, COD, TOC and BOD reduction were considered. Almost completely color reduction was achieved for the simulated as well as industrial wastewater, but only in case of ozone-based AOPs. The H2O2/UV processes were found highly not effective for industrial application. For industrial wastewater the COD and TOC decrease were not very high (10% of COD and 20% of TOC) in contrast to simulated one (90% and 50%, respectively). However, the mineralization, biodegradability and Average Oxidation State (AOS) assessment indicated that the application of AOPs resulted in more oxidized by-products. The toxicity assessment based on V. fischeri bacteria proved extremely high toxicity of BR5 (EC50=3.86±0.32mg/L). All of the tested ozone-based AOPs increased biodegradability and decreased toxicity, proving that oxidation should be performed before biological treatment. The cost analysis and the obtained results showed that O3 and O3/H2O2 (0.005M) can be effectively used in the industry.