Fenton Oxidation Process Research Articles

Synchronous COD removal and nitrogen recovery from high concentrated pharmaceutical wastewater by an integrated chemo-biocatalytic reactor systems

Present report, an investigation of highly concentrated and low bio-degradable pharmaceutical wastewater (HCPWW) treatment; simultaneously ammoniacal nitrogen recovery for struvite fertilizer. The use of multiple solvents and many formulation processes in HCPWW, resulting highly refractory chemicals. Here, in this study focused on evaluation of chemo-biocatalysts for the removal of refractory organics, nitrogen recovery from HCPWW. The initial organics, and nitrogen content in HCPWW was 20,753 ± 4606 mg/L; BOD, 6550 ± 1500 mg/L and NH4+-N, 1057.9 ± 185.8 mg/L. Initially, the biodegradability (BOD5: COD ratio from 0.32 to 0.45) of HCPWW, which was improved by heterogeneous Fenton oxidation (HFO) processes, and porous carbon (PCC, 30 g/L), along with FeSO4.7H2O, 200 mg/L and H2O2 (30% v/v), 0.4 ml/L were used as a catalyst in a weakly acidic medium. For the biocatalytic processes, the microbial culture cultivated from sewage and incorporated into a Fluidized Immobilized Carbon Catalytic Oxidation reactor (FICCO), and dominant species are Pseudomonas Putida sp., Pseudomonas Kilionesis sp., and Pseudomonas Japonica sp., which is identified by using 16 S rDNA sequencing analysis. The COD and BOD5 removal efficiency of 65–93% and 70–82%, and follow the pseudo-second-order kinetic model with the rate constants of 1.0 × 10−4 L COD−1 h−1, 1.5 × 10−3 L COD−1 h−1 and 3.0 × 10−3 L COD−1 h−1 in the HFO–FICCO-CAACO catalytic processes. The optimized hydraulic retention time (HRT) of FICCO reactor was 24 h, and 1 h for the Chemo-Autotrophic Activated Carbon Oxidation (CAACO) reactor for maximum organics removal. MAP (Magnesium Ammonium Phosphate precipitation) process showed 90% of NH4+-N elimination and recovered it as a struvite fertilizer at an optimum molar ratio of 1:1.3:1.3 (NH4+-N: Na2HPO4.2H2O: MgO). FT-IR, UV–visible, and UV-fluorescence data confirm the effective elimination of organics. Hence, this integrated treatment system is appropriate for the management of pharmaceutical wastewater especially elimination of complex organic molecules and the recovery of nitrogen in the wastewater.

Synergistic effect of Fenton oxidation and adsorption process in treatment of azo printing dye: DSD optimization and reaction mechanism interpretation

ABSTRACT The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO4/H2O2) and heterogeneous (Fe2(MoO4)3/H2O2) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20–180 mg L−1), iron concentration (0.75–60 mg L−1), pH (2–10) and hydrogen peroxide concentration (1–11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

Carbon encapsulated iron oxide for simultaneous Fenton degradation and adsorption of cationic and anionic dyes from water

Adsorption and Fenton oxidation processes are considered the most effective ways to treat industrial dye effluent. However, the separation of adsorbent materials and the leaching of secondary pollutants are big hurdles. To resolve these issues, here, we have developed a unique hybrid structure (Fe3O4 @C) by encapsulating iron oxide into carbon shells using olive mill waste in a one-step process. The resulting unique core-shell Fe3O4 @C structure possessed both tunned surface functional groups (carboxylic, carbonyl, and amines) and magnetic properties, which can be easily separated from treated water using a magnet. Upon using Fe3O4 @C as a catalyst, it simultaneously removed/ degraded both Congo red (CR) and methylene blue (MB) up to 94% through Fenton oxidation. ICP-MS analysis detected negligible (6.6 ppb) iron leaching even in Fenton degradation, which is far lower than the allowable leaching limit of 300 ppb showing the efficacy of the developed structure. This is due to the core-shell structure where Fe3O4 remains active inside the core due to dual protection by encapsulating inside a semicrystalline carbon shell, which is then protected by a porous carbon matrix. This double protection assists high adsorption and maintains efficient charge transfer that favors high catalytic activity with limited iron leaching. Further to prove this Fe3O4 @C was used in 5 consecutive adsorption cycles, where it removed 94.4% MB after 5th cycle and even preserved the pristine core-shell structure and chemical bonds as indicated by ex-situ Energy-dispersive X-ray spectroscopy, High-angle annular dark field, High-angle annular bright field, and X-ray photoelectron spectroscopy analysis. Hence, this study successfully showed that olive waste could be converted into a functional material that can further be used at a large scale for pollutant removal from wastewater.

Pre-treatment of real pharmaceutical wastewater by heterogeneous Fenton and persulfate oxidation processes

This study compares the pre-oxidation of pharmaceutical wastewater by hydroxyl radical based advanced oxidation (HR-AOP) and a sulfate radical based advanced oxidation process (SR-AOP). The heterogeneous Fenton process is chosen as a model HR-AOP and persulfate (PS) activation as a model SR-AOP. The pre-treatment efficacy of both processes in terms of TOC, and COD removals using Fe3O4-rGO catalyst were considered. Under the investigated experimental conditions, both processes yielded fluctuating COD values with time. The heterogeneous Fenton process discovered to be the most efficient to remove 68.7% TOC in 180 min of treatment, when Fe3O4-rGO: H2O2 = 300 mg L−1:150 mM H2O2 was used at pH 3. Notably, the heterogeneous Fenton system was not considerably inhibited at the natural pH of pharmaceutical wastewater (6.75), as the process successfully removed 64.6% TOC. On the other hand, in persulfate activation studies, Fe3O4-rGO: PS = 400 mg L−1: 5 mM was the ideal condition for removing 59.5% TOC in 180 min at pH 3. Whereas the natural pH condition significantly inhibited the TOC removal, as only 20.8% TOC removal was feasible. The wastewater characterisation before and after Fenton treatment reveals that Fenton oxidation leads to an increase in inorganics (chlorides: 160 ± 15 mg L−1, nitrates: 63.14 ± 3.08 mg L−1, sulfates: 266.31 ± 31.39 mg L−1) necessitating an additional treatment step to reduce COD and inorganics further.

Variation of the toxicity caused by key contaminants in industrial wastewater along the treatment train of Fenton-activated sludge-advanced oxidation processes

Industrial wastewater contains a mixture of refractory and hazardous pollutants that have comprehensive toxic effects. We investigated the treatment of a long-chain industrial wastewater treatment train containing Fenton, biological anoxic/oxic (AO), and heterogeneous ozone catalytic oxidation (HOCO) processes, and evaluated their detoxification effect based on the analysis of the genic toxicity of some key contaminants. The results showed that although the effluent met the discharge standard in terms of traditional quality parameters, the long-chain treatment process could not effectively detoxify the industrial wastewater. The analysis results of summer samples showed that the Fenton process increased the total toxicity and genotoxicity of the organics, concerned metals, and non-volatile pollutants, whereas the A/O process increased the toxicity of the organics and non-volatile pollutants, and the HOCO process led to higher toxicity caused by metals and non-volatile pollutants. The outputs of the winter samples indicated that the Fenton process reduced the total toxicity and genotoxicity caused by non-volatile pollutants but increased that of the organics and concerned metals. The effect of the A/O process on the effluent toxicity in winter was the same as that in summer, whereas the HOCO process increased the total toxicity and genotoxicity of the metals in winter samples. Correlation analysis showed that various toxicity stresses were significantly correlated with the variation of these key pollutants in wastewater. Our results could provide a reference for the optimization of industrial wastewater treatment plants (IWTPs) by selecting more suitable treatment procedures to reduce the toxicity of different contaminants.

A rational strategy of combining Fenton oxidation and biological processes for efficient nitrogen removal in toxic coking wastewater

Effective removal of nitrogen from coking wastewaters is a great challenge, since conventional biological technologies commonly suffer from concentrated bio-toxic components such as phenolic compounds and thiocyanide (SCN-). This study has successfully developed a novel ternary process for efficiently removing nitrogen from a practical coking wastewater, by rationally combined biological pretreatment, Fenton sub-pretreatment and final partial nitrification–denitrification (PN) process. It was noted that the oxic biological pretreatment (OP) could degrade above 80 % of COD and SCN- in the wastewater, by adopting the pristine coking wastewater sludge. Fenton sub-pretreatment would further degrade the residual toxic organics and protect the metabolic activity of nitrobacteria and denitrobacteria, realizing the efficient removal of NH4+-N and TN that occurred in the final PN process with self-cultivated sludge. This work can provide an interesting strategy by rationally combining biological-physicochemical processes for nitrogen removal in toxic industrial wastewaters.

A comprehensive investigation of toxicity and pollution potential of municipal solid waste landfill leachate.

It is evident from the literature that research on the treatment of leachate generated from municipal solid waste (MSW) landfills has been a focus area of environmental management. However, the available information is discrete because most studies have reported only one or a couple of aspects of either closed or active MSW landfill leachate treatment. Hence, this investigation has focused on comprehensive attributes of both closed landfill leachate (CLL) and active landfill leachate (ALL), including generation, characterisation, and toxicity assessment to quantify and establish their pollution potential. The results indicated that CLL generation is higher (188.59 m3/d) than ALL (49.53 m3/d). The concentrations of principal physical, chemical, and biological constituents and concomitant leachate pollution index were higher in CLL (33.20) than in ALL (26.65). Furthermore, the germination indices of CLL (57.48) and ALL (79.14) and tail DNA damage of CLL (56.49%) and ALL (23.8%) ratified greater phytotoxicity and genotoxicity potential, respectively of CLL over ALL. The reasons for the variations in the generation, characteristics, and toxicity of CLL and ALL were discussed in detail. Evaluation of the commonly used landfill leachate treatment methods through the analytical hierarchy process confirmed that the activated sludge process and Fenton oxidation process are the most and least preferred treatment methods. The comprehensive investigation of CLL and ALL have established their pollution potential and the inevitable necessity for their treatment. The findings of this investigation will serve as a ready reference for researchers from academia and industry who work on the monitoring, treatment, and management of landfill leachate.

Improvement of color stability using a chelating agent in model soft beverages subjected to Fenton reaction

AbstractThe colorants found in beverages are sensitive to degradation resulting in a loss of color, which can affect the perception of the product quality by the consumer. The Fenton reaction is one of the possible degradation pathways. The Fenton oxidation process is a catalytic reaction of hydrogen peroxide (H2O2) with ferrous ions (Fe2+) that generates hydroxyl radicals able to degrade the organic molecules present in the solution. In this work, the effect of the Fenton reaction in colored model soft beverages was studied using UV–visible spectrometry. The naphtol blue black was selected as a benchmark dye because it can be easily followed to probe the Fenton process. The percent degradation of this synthetic dye in an aqueous solution at pH = 3.4, simulating conditions in beverages, was monitored in the presence of FeSO4 and H2O2. Other pHs (pH = 2.7, 6.1, and 10) were also tested to obtain a full picture of the phenomenon. In an attempt to prevent the dye degradation by the Fenton reaction occurring in beverages, the effect of the addition of EDTA, a chelating metal agent able to form complexes with iron ions, was evaluated, as a model. The effect of the EDTA concentration and the influence of the pH were also explored.

CaO2-based electro-Fenton-oxidation of 1,2-dichloroethane in groundwater

It has been well recognized that the Fenton reaction requires a rigorous pH control and suffers from the fast self-degradation of H2O2. In an effort to resolve the technical demerits of the conventional Fenton reaction, particular concern on the use of CaO2-based Fenton reaction was paid in this study. To realize the practical use of CaO2 in the Fenton reaction for groundwater remediation, it could be of great importance to control its reaction rate in the subsurface. As such, this study laid great emphasis on the combined process of electrochemical oxidation and CaO2-based Fenton oxidation, using 1,2-dichloroethane (1,2-DCA) as a model compound. It was hypothesized that the reaction rate is also highly contingent on the formation of Fe(II) (stemmed from iron anode oxidation). Eighty percent of 1,2-DCA were degraded by the CaO2-based Fenton reaction. The final pH was neutral, inferring that the reaction could be a viable option for the subsurface environment. Moreover, the supply of electric current in an iron anode expedited 1,2-DCA degradation efficiency from 35 % to 62 % via electrically generated Fe(II), which donated electrons to H2O2, producing more hydroxyl radicals. An anode-cathode configuration from the single-well system enhanced the degradation of 1,2-DCA, with less amount of energy consumption than the double-well system. Based on results, CaO2-based electro-Fenton oxidation can remove well 1,2-DCA in groundwater and can be a strategic measure for groundwater remediation.

Cost-effective Application of Fenton Oxidation Process to the Biologically Treated Leachate Containing Refractory Organics and Nitrite

This paper presents an economic application of Fenton oxidation process to biological treatment effluent containing high-strength nitrite and refractory organics. To cope with two major drawbacks in applying Fenton oxidation process to the nitrite-rich effluent simultaneously, i.e. expensive reagent and excessive sludge production, we examined two pretreatment methodologies prior to the application of Fenton process in the following way. First, residual nitrite in the biologically treated leachate (BTL) was removed with iron-catalyzed air oxidation (ICAO) as a cost-effective pretreatment. The time necessary for ICAO reaction is approx. 5 hr. Secondly, to reduce organic loads iron sludge was regenerated for an alternative coagulant. With the regenerated iron sludge, the dose of Fenton’s regent can be reduced by half to remove residual COD in the BTL.

Coordination-driven Cu-based Fenton-like process for humic acid treatment in wastewater

Fenton oxidation process is effective in organic pollutant degradation during wastewater treatment, but subject to narrow pH range and secondary pollution. In this work, an application-promising alternative, i.e., coordination-driven Cu-based Fenton-like process, was proposed for wastewater treatment using humic-acid (HA) as the target contaminant. The results showed that the removal of HA through Cu-based Fenton-like process can reach 70% under the condition of pH 8.0, 146.8 mmol/L H2O2, 146.8 μmol/L Cu (II), 50 °C, and 4 h. Addition of Cl− could significantly accelerate the reaction process through coordination with copper ions, while HCO3− and P2O74− exhibited opposite effects. Increasing temperature is also beneficial for advancing the reaction, and the removal of HA followed pseudo-first-order kinetics. Fluorescence spectroscopic analyses showed that the removal of HA experienced a two-stage process, i.e., oxidation followed by degradation, which is dependent of the presence of coordination ions. Parallel factor analysis was used to characterize the change of fluorescence components. Three fluorescent components, i.e., terrestrial humic-like, UV/visible terrestrial humic-like and protein-like component were identified, all of which were effectively removed. This study deepens our understanding on Cu-based Fenton-like process, and may provide a promising technology for refractory wastewater treatment.

Optimization of Fenton Oxidation Process for Degradation of 1-Butyl-3 Methyl Imidazolium Chloride (BMIMCL) Using Response Surface Methodology

The degradation of 1-butyl 3-methyl imidazolium chloride (BMIMCl) ionic liquid (IL) by Fenton oxidation has been studied. The optimization of operating parameters for maximum degradation of BMIMCl has been carried out using the Central Composite Design (CCD) of Response Surface Methodology (RSM). The three independent input parameters selected were the dosage of Hydrogen Peroxide (H2O2), the dosage of iron (Fe2+), and the pH of the output or response selected was Total Organic Carbon (TOC) removal efficiency. Experiments were carried out according to the experimental design provided by CCD. For TOC Degradation, the model’s R2 and R2adj correlation coefficients between experimental and model-predicted values were 0.9769 and 0.9561, respectively. This indicates a satisfactory correlation of experimental results with model-predicted values. The optimum values of operating parameters for maximum degradation were found to be H2O2=307 mM (X1), Fe2+=1.1 mM (X2), and (pH)=3.3 (X3), for a reaction time of 120 min. For these operating parameters, the experimental result for TOC removal efficiency was found to be 72.89% as compared to the model-predicted value of 73.67%. These results indicate that the values were closely correlated with each other and thus the model was validated satisfactorily. Overall, the results indicate that the BMIMCl ionic liquid can be effectively degraded by the Fenton oxidation process.

Utilization of Fenton oxidation approach in wet phosphoric acid process for mitigating foam generation

Significant amounts of foam generated during the production of phosphoric acid would severely occupy the head space in the reactors, thereby reducing output capacity dramatically. Here, we first proposed a green and clean approach based on Fenton oxidation theory to mitigate the generation of foam. The effect of H2O2 dosage, FeSO4 dosage, and pH value on the defoaming performance were investigated systematically. Moreover, the defoaming performance between Fenton oxidation process and traditional defoamer were compared and the defoaming mechanism was described with the help of XRD analyses. The results obtained from the Fenton oxidation process demonstrate that the use of H2O2 in conjunction with FeSO4 are beneficial to mitigating the foam generation, and the defoaming performance is positively correlated to the dosage. Furthermore, Fenton oxidation process outperforms than that of traditional defoamer in terms of reducing foam generation. The defoaming mechanism is ascribed to the fact that the organic substrates existing on the phosphate concentrate surface could be completely decomposed and the soluble carbonate minerals were prone to being dissolved during the regulation of pH value, thereby inhibiting the production of CO2 gas. This work is helpful in providing guidance for utilizing a green and clean approach based on advanced oxidation theory to mitigate the foam generation during the wet phosphoric acid process. More importantly, it provides a theoretical basis for optimizing this type of processing methods.

An efficient ultrasonic-assisted bleaching strategy customized for yak hair triggered by melanin-targeted Fenton reaction

Promoting processing efficiency and taking advantage of agricultural by-products are two promising ways to achieve sustainable textile industry. This study presents a customized efficient ultrasonic-assisted bleaching strategy for yak hair – a widely existing but underexploited secondary dark shade fibre from yak. A melanin-targeted Fenton oxidation process is established which involves three phases, i.e., (I) incorporation of Fe2+ ions with melanin, (II) catalytic oxidative bleaching using hydrogen peroxide (H2O2), and (III) reductive cleansing. The bleaching efficacy, dyeing performance and tensile property of yak hair treated with and without ultrasound were explored and compared. Further, the ultrasonic bleaching mechanism in terms of the catalytic effect of Fe2+ ions, the promotion of H2O2 decomposition, removal of melanin granule from yak hair, were demonstrated. Finally, the main effects and interactions of parameters in phase II, and optimal condition were obtained through mathematical modelling based on a central composite design (CCD). Results reveal that ultrasonic bleaching dramatically enhances the whiteness index (WI) of yak hair from 11 to 45 which is 44.6% higher than those bleached without ultrasound, and also promotes the uptake of acid dyes. There is only 15% tensile strength loss and 14% elongation increment of yak hair after ultrasonic bleaching, rising from a slight damage of cuticle layer and cleavage of disulfide bonds, respectively. In the study of bleaching mechanism, Fe2+ ion is confirmed to improve the H2O2 decomposition rate by 20.9% which further runs up to 35.9% after introducing ultrasound. Ultrasound increases the concentration of hydroxyl radicals (HO) by 94% which are the main oxidative species participating in bleaching confirmed by HO scavenging experiment. The porous structure was observed on the cross section of yak hair stemming from the removal of melanin granules contributed by the cleaning action of ultrasound. A theoretical highest WI of 52.4 can be achieved under an optimal condition based on the CCD study. In general, the proposed melanin-targeted bleaching strategy for yak hair that integrates ultrasonic technology and Fenton reaction, is beneficial to the development of sustainable textile industry from material and processing perspectives.

Degradation of Tartrazine Using Hydrodynamic Cavitation‐Based Hybrid Techniques and Fenton Chemistry

AbstractDegradation of the tartrazine was investigated systematically using the Fenton oxidation process and hydrodynamic cavitation (HC)‐based hybrid techniques. The operating parameters, such as the inlet pressure, the initial pH, the initial concentration of tartrazine, and the molar ratio of the Fenton reagents, were optimized. A maximum degradation of 12.50 % was observed using HC alone at 5 bar pressure and a solution pH of 2, while Fenton chemistry showed 92.40 % degradation at a Fe2+/H2O2 molar ratio of 1:36. HC in conjugation with H2O2 or Fenton reagents showed maximum degradation values of 92 and 96.40 %, respectively. The degradation follows a pseudo‐first‐order kinetics with respect to the concentration of tartrazine, for Fenton chemistry and the HC‐based hybrid techniques.

Investigation of the treatability of essential oil industry wastewater using Fenton oxidation process

Investigation of the treatability of essential oil industry wastewater using Fenton oxidation process

Treatment of Waterborne Coating Wastewater by Coagulation Sedimentation Fenton Oxidation Process

waterborne coatings have become the development trend of the coating industry because of their less use of organic solvents and good environmental protection performance. However, the wastewater produced in the production process of waterborne coatings has become a difficult pollution source. Based on this, this paper uses coagulation sedimentation method and Fenton oxidation method to treat waterborne coating wastewater. Taking the COD of treated wastewater as the research index, this paper studies various factors affecting the treatment effect of coagulation sedimentation and Fenton oxidation. Through single factor analysis, the results show that the best dosage of PFS and PAM is PFS: 8 g/L and PAM: 0.8 g/L; In Fenton oxidation, the dosage of H2O2 is 9.98mL/L, the dosage of FeSO4 · 7H2O is n (Fe2+): n (H2O2) = 1:6, pH is 2, and the dosage times are 2.

Comparison of kinetics and costs of Fenton and photo-Fenton processes used for the treatment of a textile industry wastewater

In this study, the treatment of textile industrial wastewater by Fenton and Photo-Fenton oxidation processes was investigated. For this purpose, the pH, Fe2+ and H2O2 concentrations with the best organic matter and color removal were determined in the Fenton process and comparison with Fenton was made by Photo-Fenton oxidation at the optimal Fe2+/H2O2 ratio. The influent COD and TOC values of the wastewater used in the study were 848 mg/L and 253 mg/L, respectively. With the Fenton process, the best organic matter and color removal was obtained at pH 3, at 200 mg/L Fe2+ and 300 mg/L H2O2 concentrations. Under these conditions, 88.9% COD, 84.2% TOC and over 97% color removal were obtained with Fenton oxidation, and 93.2% COD, 88.9% TOC and 98% color were obtained with Photo-Fenton oxidation. However, when Fe2+ and H2O2 amounts were reduced to 50 mg/L and 75 mg/L, both organic matter and color removal were reduced with Fenton process, while higher organic matter removal and color removal were achieved with Photo-Fenton process. The total cost was changed between 9.56-16.88 €/m3 and 13.46–20.13 €/m3 with Fenton and Photo-Fenton oxidation process for all Fe2+/H2O2 ratios, respectively. With the Photo-Fenton oxidation process, higher organic matter removal was obtained at optimum Fe2+ and H2O2 concentrations. In addition, less Fe2+ and H2O2 chemicals were used in Photo-Fenton oxidation process to achieve the same removal efficiency compared to the Fenton oxidation process.

DEGRADATION OF METHYL BLUE BY FENTON PROCESS

In this study, the oxidative degradation of Methyl Blue (MB) triphenylmethane dye, in aqueous solution by Fenton oxidation process was investigated. The UV-Vis spectral changes of Methyl Blue dye during discoloration process were studied. Kinetic study was done to find out the effect of pH on discoloration rate of dye solution.

DEGRADATION OF METHYL BLUE BY FENTON PROCESS

In this study, the oxidative degradation of Methyl Blue (MB) triphenylmethane dye, in aqueous solution by Fenton oxidation process was investigated. The UV-Vis spectral changes of Methyl Blue dye during discoloration process were studied. Kinetic study was done to find out the effect of pH on discoloration rate of dye solution.