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.     

Degradation of Aqueous Pharmaceuticals by Ozonation and Advanced Oxidation Processes: A Review

A vast number of pharmaceuticals have been detected in surface water and drinking water around the world, which indicates their ineffective removal from water and wastewater using conventional treatment technologies. Concerns have been raised over the potential adverse effects of pharmaceuticals on public health and aquatic environment. Among the different treatment options, ozonation and advanced oxidation processes are likely promising for efficient degradation of pharmaceuticals in water and wastewater. Recent progress of advanced oxidation of aqueous pharmaceuticals is reviewed in this paper. The pharmaceuticals and non-therapeutic medical agent of interest include antibiotics, anticonvulsants, antipyretics, beta-blockers, cytostatic drugs, H₂ antagonists, estrogenic hormone and contraceptives, blood lipid regulators, and X-ray contrast media.     

Degradation of Recalcitrant Surfactants in Wastewater by Ozonation and Advanced Oxidation Processes: A Review

Surfactants are used in varieties of industrial cleansing processes as well as in consumer products. Spent surfactants normally enter domestic or industrial wastewater and are treated biologically. However, some of them are resistant to biodegradation and are released into the environment. Thus, the toxicity and environmental persistence of these surfactants are emerging concerns. Based on extensive review of the literature, ozonation and advanced oxidation using various combinations of ozone, hydrogen peroxide, ultraviolet light irradiation, and iron salts were found effective in degrading recalcitrant surfactants, including linear alkylbenzene sulfonates, alkylphenol ethoxylates, and quaternary ammonium surfactants. Biodegradability of these surfactants was improved after the treatment to some extent in the aqueous solution as well as in real wastewaters.     

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 Organic Pollutants by the Advanced Oxidation Processes

A kinetic model hss been developed for the degradation of organic pollutants concerning with hydroperoxide ion as the initial step for generation of hydroxyl radical and its subsequent reac-tion mechanisms. Rate equstions were derived for depletion of ozone and pollutants in the peroxone oxidation process using ozone and hydrogen peroxide as combined oxidants. Kinetic data obtained experimentally form the hydrogen peroxide-ozone reaction and peroxone oxidstion of nitrohenzene were analyzed by using the proponse rate equations.     

Studies in Radiation Chemistry: Application to Ozonation and Other Advanced Oxidation Processes

Advanced oxidation/reduction processes (AORPs) are an alternative water treatment that is becoming more widely utilized. Our radiation-chemistry based studies are being used to develop a fundamental understanding of AOP treatment options, and are divided into three complementary types of contaminants; disinfection by-products (DBPs), emerging pollutants of concern (EPoCs), and natural organic matter (NOM). More than 600 DBPs have been identified, and one class that appears to have severe potential adverse health effects is the halonitromethanes (HNMs). Of the nine HNMs, trichloronitromethane (chloropicrin) is the most common, with levels up to 180 nM in US drinking waters. EPoCs are of interest because of their biological activity at low concentrations in water and while the initial focus was on endocrine disruptor chemicals (EDCs) this class has now been expanded to include many other recalcitrant chemicals such as hormones, antibiotics, industrial contaminants, and health care products. Natural organic matter is one of the most common radical scavengers in natural waters and therefore may adversely affect AOPs. Our approach is to study NOM both directly and using model compounds thought to be representative of structural components of this complex material.     

Oxidation of Propylene Glycol Methyl Ether Acetate Using Ozone-Based Advanced Oxidation Processes

The present study investigates the degradation of PGMEA and its TOC removal using O₃, UV/O₃, O₃/H₂O₂, and UV/H₂O₂ processes under various experimental conditions. Ozonation of PGMEA was substantially enhanced in the presence of UV light and H₂O₂. Approximately 33% of TOC enhancement was noted in UV/O₃ process over ozonation process. A linear relationship between PGMEA and H₂O₂ decomposition was observed in O₃/H₂O₂ and UV/H₂O₂ processes. The influence of solution pH on the decomposition of PGMEA was investigated and found that basic medium was the most efficient in all AOPs. After 60 minutes 62.4%, 100%, 90% and 54% of PGMEA decomposition at pH 10.0 was observed in O₃, UV/O₃, O₃/H₂O₂, and UV/H₂O₂ processes, respectively. It is concluded that UV/O₃ process is a promising approach for the oxidation and removal of PGMEA.     

Combination of Ozone with Activated Carbon as an Alternative to Conventional Advanced Oxidation Processes

The objective of this study was to compare the efficiency of O₃/granular activated carbon (GAC) to enhance ozone transformation into ·OH radicals, with the common advanced oxidation processes (O₃/OH^?, O₃/H₂O₂). The results obtained with model systems under the given experimental conditions showed that the system O₃/OH^? (pH 9) and O₃/H₂O₂ (pH 7, [H₂O₂] = 1·10^?5 M) are more efficient than O₃/GAC (pH 7, [GAC] = 0.5 g/L) to enhance ozone transformation into ·OH radicals. However, in Lake Zurich water the O₃/GAC process has a similar efficiency as O₃/H₂O₂ for ozone transformation into ·OH radicals. The results also show that the presence of GAC during Lake Zurich water ozonation leads to (i) removal of hydrophilic and hydrophobic micropollutants, (ii) reduction of the concentration of CO₃ ^2?/HCO₃ ^?, and (iii) decrease of the concentration of dissolved organic carbon (DOC) present in the system.     

Oil-Refinery Wastewater Treatment Aiming Reuse by Advanced Oxidation Processes (AOPs) Combined with Biological Activated Carbon (BAC)

The treatment of a refinery wastewater by Advanced Oxidation Processes (AOP) coupled with Biological Activated Carbon (BAC) was investigated aiming to generate water for reuse. O₃/UV and H₂O₂/UV processes were employed to oxidize the organic matter and the BAC process to remove residual organic matter from the AOP effluent. AOP promoted oxidation of recalcitrant organic matter as observed by moderate drops on the treated wastewater absorbance (31–79%) and TOC values (10–18%). BAC filters showed to be effective, reaching average efficiencies of 65% in a sufficiently long period of operation (84 days), while GAC filters were saturated after 28 days. Effluent TOC values in the range of 4 to 8.5 mg/L were achieved by the combined treatment (H₂O₂/UV + BAC), allowing water reuse.     

Ozonation and Advanced Oxidation Treatment of Emerging Organic Pollutants in Water and Wastewater

A vast number of persistent organic pollutants have been found in wastewater effluent, surface water, and drinking water around the world. This indicates their ineffective removal from water and wastewater using conventional treatment technologies. In addition to classical persistent organics such as organochlorine insecticides, solvents, and polychlorinated biphenyls, a growing number of emerging pollutants of both synthetic and natural origins have been identified as major environmental pollutants in recent years. A variety of advanced and conventional treatment options have been suggested for the removal and/or destruction of these persistent organics in water and wastewater, such as chemical oxidation, activated carbon adsorption, and membrane filtration. Of these options, chemical oxidation using ozone, alone or in combination with additional physical/chemical agents (i.e., advanced oxidation), has been proved a highly effective treatment process for a wide spectrum of emerging aqueous organic pollutants, including pesticides, pharmaceuticals, personal care products, surfactants, microbial toxins, and natural fatty acids. In this paper, we discuss the emerging organic pollutants of concern in the aquatic environment and focus on the issues associated with their removal using ozonation and advanced oxidation processes.     

Advanced Oxidation Treatment of Drinking Water: Part II. Turbidity,Particles and Organics Removal from Lake Huron Water

Pre-coagulation ozonation has been reported to be effective in drinking water treatment processes. Limited data are available on the impact of advanced oxidation processes (AOPs) on Lake Huron water which serves as a primary source of drinking water for many communities around the Great Lakes region. Impact of ozone/hydrogen peroxide based AOP on Lake Huron water was studied. The results show that AOPs can achieve higher particles removal in finished water and deliver improved filtered water turbidity compared to the conventional treatment process. Sharp decline in ultraviolet absorbance at 254 nm (UV₂₅₄) was observed immediately following AOP treatment while only minimal overall decrease in dissolved organic carbon (DOC) was achieved.     

Estimation Of The Relative Importance Of Free Radical Oxidation And Direct Ozonation/UV Radiation Rates Of Micropollutants In Water

The relative importance of free radical and direct ozonation/photolysis oxidation of micropollutants in water can be estimated from simple kinetics of aqueous ozonation reactions provided these reactions develop in the slow kinetic regime of absorption. Knowledge of kinetic expressions of free radical initiation reactions and direct ozone-micropollutant or UV radiation-micropollutant reactions (and corresponding parameters: reaction rate constants, quantum yields, etc.) allows an estimation of the reaction rate ratios for any micropollutant in the ozone alone and combined with hydrogen peroxide and/or UV radiation oxidation systems.     

Modelisation Of Micropollutant Removal In Drinking Water Treatment By Ozonation Or Advanced Oxidation Processes (O3/H2O2)

A simulation program is described, tested and used, to predict micropollutant removal in an ozonation bubble tower with or without hydrogen peroxide addition. To compute the removal efficiency, we need to know the chemical reactivity between organic compounds and oxidant species (molecular ozone and hydroxyl radicals), the ozone mass transfer from the gaseous phase to the liquid phase (k_La) and the hydrodynamic model describing the reactor. In this case, we divide the reactor into three parts (water arrival, air arrival and intermediate zones). Each part is modelled using completely stirred tank reactors in series (CSTR).

In each CSTR, the calculation of oxidant concentrations (O₃, H₂O₂) is made through mass balance equations and a semi-empirical formula which gives hydroxyl radical concentrations as a function both of ozone concentration and the main characteristics of the water to be treated (pH, TOC, alkalinity). Another semi-empirical formula links ozone consumption to the same characteristics.     

Advanced Oxidation of Textile Wastewaters

Model dyeing and laundering wastewaters produced during two basic technological operations of the textile industry were subjected to treatment by advanced oxidation processes (AOPs). The following agents were used: ozone (O₃), hydrogen peroxide (H₂O₂) and UV radiation. They were applied separately and in all possible combinations: O₃ + UV, O₃ + H₂O₂, UV + H₂O₂, as well as all three at the same time: O₃ + UV + H₂O₂. Effluents before and after the treatment were analyzed according to requirements of the Polish Standards that included pH, color threshold, COD and concentration of anionic and non-ionic surfactants. Ozonation was carried out in a lab-scale bubble column reactor with a centrally located UV burner. The most effective version of AOPs proved to be the simultaneous use of all three agents. In the case of such treatment of dyeing wastewaters nearly complete discoloration and full decomposition of surface-active substances were obtained at 80% reduction of COD. A similar tendency was observed in the case of laundering wastewater, though in that case the results were slightly worse, which may be explained by much higher initial concentrations of the pollutants. Good treatment effects have also been obtained in combined treatment by simultaneous use of hydrogen peroxide and ozone.     

Aqueous Ozonation Of Surfactants: A Review

The aqueous ozonation reactions of surfactants have been reviewed, including the degree of reaction and ozonation byproduct identity. Compounds are classified into three groups: anionic, cationic and non-ionic surfactants. Experimental conditions for each study reviewed are summarized. Much work has been carried out under conditions unlikely to occur during drinking water treatment. Thus, most of the findings of the papers reviewed cannot be directly applied to potable water treatment. However this review can serve to indicate the likely reactivity of the individual surfactants towards ozone and the possible byproducts formed. This reactivity depends mainly upon the chemical structure of the surfactants. The removal of surfactants is pH dependent, with the best results being obtained in alkaline media. High ozone doses usually do not cause complete disruption of the surfactants, while smaller doses are sufficient to enhance their biodegradation.     

Treatment of Wastewater Coming from Painting Processes: Application of Conventional and Advanced Oxidation Technologies

The process of car body painting is one of the manufacturing processes that may involve the use of organic solvents for surface treatments. As a result of this process, wastewaters containing raw materials and auxiliary products used during the cleaning step are produced. The main objective of this study is to find an appropriate purification technique to eliminate or reduce the contamination present in this kind of wastewater. Different treatments were investigated: ozonation, ozonation combined with hydrogen peroxide, photo-Fenton treatment, and coagulation- flocculation.     

Comparison of Different Advanced Oxidation Processes Involving Ozone to Eliminate Atrazine

The oxidation of the herbicide atrazine by advanced oxidation processes (AOP) has been studied. The experiments were carried out in a tubular photoreactor, 2.5 L capacity, capable of providing good contact between the liquid and gas reactants. The decomposition rate of atrazine was determined at different pH using UV radiation, Hydrogen Peroxide, Ozone, Ozone/UV, Ozone/H₂O₂, H₂O₂/UV and Ozone/H₂O₂/UV processes. The effect of three different pH values was studied (4.7, 6.8, 11.7).     

Treatment of Jewelry Manufacturing Effluent Containing Cyanide Using Ozone-Based Photochemical Advanced Oxidation Processes

This article considers Advanced Oxidation Processes involving O₃, O₃/UV, O₃/H₂O₂/UV, and H₂O₂/UV to destroy cyanide in jewelry manufacturing wastewaters. All experiments were performed in a semibatch reactor. The results showed that total cyanide can be reduced with different reaction rates, and the decrease of total cyanide can be described by pseudo–first-order kinetics. The reaction was performed under different pH values and H₂O₂ dosages to find the optimal conditions for the oxidation processes. The ozonation process destroyed total cyanide faster at a pH = 12, whereas ozonation combined with H₂O₂ and/or UV destroyed cyanide faster at a pH =10. The total cyanide destruction rate in the UV/H₂O₂ (700 mg/L) treatment was the highest among all studied processes, with removal efficiencies of 99% for CN^?, 99% for COD and 99% for TOC.     

Removal of Natural Organic Matter from Groundwater Using Advanced Oxidation Processes at a Pilot Scale Drinking Water Treatment Plant in the Central Banat Region (Serbia)

To improve water quality, a pilot-scale evaluation into upgrading the conventional treatment process was conducted. By following DOC content, UV₂₅₄ absorbance, SUVA and by-products formation, three oxidative pre-treatments were evaluated: pre-ozonation (2.2 g O₃/m³); O₃/H₂O₂ process (2.2 g O₃/m³; H₂O₂:O₃ = 1:2) and O₃/H₂O₂ process (2.2 g O₃/m³; H₂O₂:O₃ = 2:1). The second pre-treatment gave the best results, with a final average DOC content of 0.9 mg C/L, UV₂₅₄ absorbance of 0.06 cm^?1 and the lowest THMFP of 130 μg/L. UV₂₅₄ absorbance can serve as a proper indicator for predicting THM and HAA formation, yielding a correlation coefficient ≥ 0.90.     

Advanced Oxidation Treatment of Drinking Water: Part I. Occurrence and Removal of Pharmaceuticals and Endocrine-Disrupting Compounds from Lake Huron Water

The current study focuses on the occurrence of selected endocrine disrupting compounds, pharmaceuticals and personal care products in Lake Huron Water and their removal using ozone/hydrogen peroxide based pre-coagulation, advanced oxidation process (AOP). Raw Lake Huron water spiked with nine target compounds was treated in a dual train pilot scale treatment plant. None of the target chemicals showed any significant removals following conventional treatment processes (coagulation, sedimentation and filtration). Five of the nine target pollutants plummeted to concentrations below the method detection limits following AOP. For all the target compounds AOP treatment provided higher removal compared to conventional treatment.