Pilot-scale Fenton’s oxidation of organic contaminants in groundwater using autochthonous iron (original) (raw)
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Removal of organic pollutants from produced water using Fenton oxidation
E3S Web of Conferences
Produced water (PW) is the largest stream of wastewater from oil and gas exploration. It is highly polluted and requires proper treatment before disposal. The main objective of this study was to investigate the effectiveness of Fenton oxidation in degradation of organic matter in PW. The role of operating factors viz., H2O2 concentration (0.12 × 10-3 moles/L to 3 moles/L), [H2O2]/[Fe2+] molar ratio (2 to 75), and reaction time (30 to 200 minutes), on COD removal was determined through a series of batch experiments conducted in acidic environment at room temperature. The experiments were conducted with 500 mL PW samples in 1L glass beakers covered on the outside with aluminum foil to protect them from sunlight. Pre-decided amounts of ferrous sulfate heptahydrate (FeSO4.7H2O) and hydrogen peroxide (H2O2) were added to initiate the Fenton reaction. An increase in COD removal was observed with increase in reaction time and [H2O2]/[Fe2+] molar ratio. COD removal also increased with H2O2 ...
Fenton like Method for Contaminated Groundwater
2017
Advanced oxidation processes (AOPs) have been widely proposed to treat wastes, particularly less concentrated effluents. Fenton-like is a useful technique to remove different organic compounds. A supported catalyst prevents iron release during all the process. In earlier works we explored the porous structure of a modified natural clinoptilolite loaded with iron as a supported catalyst (NZ-A-Fe). This paper presents novel results for BTX (Benzene, Toluene and Xylene) removal from aqueous solution considering that adsorption and oxidation processes are taking place simultaneously. The experiment was achieved by fluxing an aqueous solution of BTX 10 mM and hydrogen peroxide using the same reservoir. After 870 min, C/Cº reaches near 10% for each pollutant corresponding to 122 bed volumes. The system removed 225 mg BTX in the present conditions (45 mg/gNZ-A-Fe). Hydrophobic Fe-zeolites can therefore be regarded as promising materials for the removal of BTX from water, since they allow the combination of efficient adsorption and oxidative degradation of BTX by H2O2 at neutral pH.
Environmental Science and Pollution Research, 2016
This study evaluated, at laboratory scale, if the using iron naturally present (0.3 mg L −1) and adding 10 mg L −1 of hydrogen peroxide was effective to remove 24.3 mgL −1 of 2,4-dichlorophenoxyacetic acid (2,4-D) from groundwater samples by simulated solar irradiation (global intensity = 300 W m −2). Under these conditions, the degradation of 2,4-D reached 75.2 % and the apparition of its main oxidation byproduct 2,4-dichlorophenol (DCP) was observed. On the other hand, pH exhibited an increasing from 7.0 to 8.3 during the experiment. Experiments using Milli-Q water at pH 7.0, iron, and H 2 O 2 concentrations of 0.3 and 10 mg L −1 , respectively, were carried out in order to study the effect of ions such as carbonate species, phosphate, and fluoride in typical concentrations often found in groundwater. Ion concentrations were combined by using a factorial experimental design 2 3. Results showed that carbonates and fluoride did not produce a detrimental effect on the 2,4-D degradation, while phosphate inhibited the process. In this case, the pH increased also from 7.0 to 7.95 and 8.99. Effect of parameters such as pH, iron concentration, and hydrogen peroxide concentration on the 2,4-D degradation by the photo-Fenton process in groundwater was evaluated by using a factorial experimental design 2 3. Results showed that the pH was the main parameter affecting the process. This study shows for the first time that using the photo-Fenton process at circumneutral pH and iron naturally present seems to be a promising process to remove pesticides from groundwater.
Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.
Pre-oxidation of an extremely polluted industrial wastewater by the Fenton?s reagent
Journal of Hazardous Materials, 2003
The pre-oxidation of an extremely polluted pharmaceutical wastewater (chemical oxygen demand (COD) value of 362,000 mg/l) using the Fenton's reagent has been systematically studied using an experimental design technique. The parameters influencing the COD removal of the wastewater, namely temperature, ferrous ion and hydrogen peroxide concentrations have been optimized to achieve a COD global reduction of 56.4%.
Treatment of organic pollutants by homogeneous and heterogeneous Fenton reaction processes
Environmental Chemistry Letters, 2018
Nowadays, the water ecosystem is being polluted due to the rapid industrialization and massive use of antibiotics, fertilizers, cosmetics, paints, and other chemicals. Chemical oxidation is one of the most applied processes to degrade contaminants in water. However, chemicals are often unable to completely mineralize the pollutants. Enhanced pollutant degradation can be achieved by Fenton reaction and related processes. As a consequence, Fenton reactions have received great attention in the treatment of domestic and industrial wastewater effluents. Currently, homogeneous and heterogeneous Fenton processes are being investigated intensively and optimized for applications, either alone or in a combination of other processes. This review presents fundamental chemistry involved in various kinds of homogeneous Fenton reactions, which include classical Fenton, electro-Fenton, photo-Fenton, electro-Fenton, sono-electro-Fenton, and solar photoelectron-Fenton. In the homogeneous Fenton reaction process, the molar ratio of iron(II) and hydrogen peroxide, and the pH usually determine the effectiveness of removing target pollutants and subsequently their mineralization, monitored by a decrease in levels of total organic carbon or chemical oxygen demand. We present catalysts used in heterogeneous Fenton or Fenton-like reactions, such as H 2 O 2-Fe 3+ (solid)/nano-zero-valent iron/immobilized iron and electro-Fenton-pyrite. Surface properties of heterogeneous catalysts generally control the efficiency to degrade pollutants. Examples of Fenton reactions are demonstrated to degrade and mineralize a wide range of water pollutants in real industrial wastewaters, such as dyes and phenols. Removal of various antibiotics by homogeneous and heterogeneous Fenton reactions is exemplified.
International Journal of Environmental Research
This work investigates the use of Fenton's process (pH 5.5 and 6; 0.10-0.50 mM Fe(II); molar ratios Fe(II) to H 2 O 2 of 1:5-1:20) combined with flocculation for the treatment of groundwater which is rich in natural organic matter (NOM) (10.6±0.37 mg C/L) and arsenic (110±6.7 µg/L). Changes to the character of the residual NOM fractions were followed, as well as the removal efficiencies of NOM and arsenic. Under optimal reaction conditions at pH 5.5, 55% of the Dissolved Organic Carbon (DOC) was removed, whilst removals of specific disinfection by-product precursors of trihalomethanes (THM), haloacetic acids (HAA) and haloacetonitriles (HAN) were 80%, 75% and 98%, respectively. Total arsenic concentrations were reduced to below 5 µg/L under all investigated experimental conditions. After the Fenton treatment, the percentage of the hydrophobic NOM fraction (humic acid and fulvic acid fraction) decreased, and the percentage of the hydrophilic fraction (acidic and non-acidic fractions) increased. The hydrophilic fraction, which was the most abundant in the treated water, was also the most reactive fraction towards THM and HAA formation, whereas the residual fulvic acid fraction contributed the most to the formation of HAN.
Abstract In these years, due to the increasing presence of molecules in industrial waste water from factories and petroleum refineries, the conventional biological methods cannot be used for complete treatment of the effluent therefore the need to newer technologies to degrade these refractory molecules into smaller molecules became very imperative. Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters. Fenton’s oxidation was one of the best known metal catalyzed oxidation reactions of water-miscible organic compounds. The mixture of FeSO4 or any other ferrous complex and H2O2 (Fenton’s reagent) at low enough pH, results in Fe2+ catalytic decomposition of H2O2 and proceeds via a free radical chain process that produces hydroxyl radicals which have extremely high oxidizing ability and could oxidize hard to decompose organic compounds in a short time. This work aims at highlighting Fenton’s oxidation processes operating at ambient conditions viz. photo-catalytic oxidation, Fenton’s chemistry and use of hydrogen peroxide. The pre-oxidation of an extremely polluted pharmaceutical wastewater, Direct Blue 71 (DB71) oil recovery industry wastewater, the fish canning industrial wastewater, Active pharmaceutical intermediates (API) in waste waters by Fenton’s oxidation process to degrade organic pollutants. The work highlights the basics of these individual processes including the reactor design aspects, the optimum parameters such as dosage of ferrous sulfate and hydrogen peroxide, pH and initial concentration of pollutants and a complete overview of the various applications to wastewater treatment by Fenton’s oxidation processes in the recent years. This study presents a general review on the effectiveness of Fenton’s technique for the treatment of semi-aerobic landfill leachate (Treatment with Fenton’s reagent appears to be an appropriate method for oxidizing recalcitrant
Industrial wastewater treated by galvanic, galvanic Fenton, and hydrogen peroxide systems
Journal of Water Process Engineering, 2018
Industrial wastewater containing effluents from 190 factories located at an industrial park in Toluca State, Mexico, was subjected to galvanic (GT), galvanic Fenton (GF), and hydrogen peroxide treatments to remove organic matter. The galvanic system uses iron-copper electrodes to produce Fe 2+ in situ. For the GF system, hydrogen peroxide was applied to produce hydroxyl radicals. The GF system does not require energy, unlike the analogous electro-Fenton system, and, in fact, it is possible to generate an electric current (∼220 mV) from the chemical reactions. A synergistic effect was observed with GF treatment at pH 2.8 and a H 2 O 2 /Fe 2+ ratio of 19:1 (i.e. 7840 mg H 2 O 2 /L and 408 mg Fe 2+ /L), leading to high removal percentages for color (76%), soluble chemical oxygen demand (71%), and total organic carbon (79%), while degradations of 43% and 48% were achieved for biochemical oxygen demand and nitrates, respectively. Fluorescence and IR spectroscopy analyses of raw and treated wastewater samples were performed with the aim of establishing the anthropic origin of the dissolved organic matter. Fluorescence spectroscopy showed that GF treatment eliminated the anthropogenic organic matter associated with aromatic groups and proteins, enhanced effluent biodegradability, did not increase toxicity, and reduced the sub-lethal effects observed for lettuce radicles. Most importantly, the removal efficiencies of GF treatment were comparable with those of analogous electrochemical advanced oxidation processes based on Fenton reactions. 1500 mg/L, with a biodegradability index (BI), defined as the biochemical oxygen demand (BOD)/COD ratio by Metcalf and Eddy, of
A review on Fenton and improvements to the Fenton process for wastewater treatment
Journal of Environmental Chemical Engineering, 2014
The increase in the disposal of refractory organics demands for newer technologies for the complete mineralization of these wastewaters. Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of such wastewaters and this study presents a general review on such processes developed to decolorize and/or degrade organic pollutants. Fundamentals and main applications of typical methods such as Fenton, electro-Fenton, photo-Fenton, sono-Fenton, sonophoto-Fenton, sono-electro-Fenton and photo-electro-Fenton are discussed. This review also highlights the application of nano-zero valent iron in treating refractory compounds.