Sequential Optimization for Minimizing Material Cost and Treatment Time of Fenton Oxidation for Textile Wastewater Treatment

This paper examines the technical and economic feasibilities of the sequential optimization technique, i.e., Taguchi coupled with principal component analysis (PCA). Fenton oxidation with four operating parameters, such as [Dye]_ini, Dye/Fe⁺² (wt/wt), H₂O₂/Fe⁺² (wt/wt), and pH, was selected as a case study. COD (%), TOC (%), and color removal efficiency were chosen as responses. Total principal component index (TPCI) values, obtained as an output of sequential optimization, were used to determine the optimized conditions for Fenton oxidation. [Dye]: 100?mg/L, Dye/Fe⁺²(wt/wt): 50, H₂O₂/Fe⁺²(wt/wt): 25 and pH: 3 were obtained as the optimized values. In addition, ANOVA and the interaction of factors showed that pH was the most significant factor with the percent contribution of 90.86%. Economic evaluation with simultaneous comparison with Taguchi and central composite design (CCD) showed that Taguchi coupled with PCA is the most economic and time-efficient optimization technique. In this study, experimental cost was reduced to $54/m³, which showed 95% reduction relative to CCD. Moreover, chemical consumption and experimental time were also reduced by approximately 95–97% and 68%, respectively. Thus, it can be concluded that Taguchi coupled with PCA is the most cost-effective and less-laborious way of optimizing multi-response processes such as Fenton oxidation.     

Post-Treatment of Pulp and Paper Industry Wastewater by Advanced Oxidation Processes

The aim of this study was to investigate the effectiveness of chemical oxidation by applying ozonation, combination of ozone and hydrogen peroxide and Fenton's processes for decolorization and residual chemical oxygen demand (COD) removal of biologically pretreated pulp and paper industry effluents. The batch tests were performed to determine the optimum operating conditions including pH, O₃, H₂O_2, and Fe²⁺ dosages. H₂O₂ addition reduced the reaction times for the same ozone dosages; however combinations of ozone/hydrogen peroxide were only faintly more effective than ozone alone for COD and color removals. In the Fenton‘s oxidation studies, the removal efficiencies of COD, color and ultraviolet absorbance at 254 nm (UV₂₅₄) for biologically treated pulp and paper industry effluents were found to be about 83, 95, and 89%, respectively. Experimental studies indicated that Fenton oxidation was a more effective process for the reduction of COD, color, and UV₂₅₄when compared to ozonation and ozone/hydrogen peroxide combination. Fenton oxidation was found to have less operating cost for color removal from wastewater per cubic meter than the cost for ozone and ozone/hydrogen peroxide applications.     

The Fenton Chemistry and Its Combination with Coagulation for Treatment of Dye Solutions

Abstract

Aqueous solutions of Acid Blue 74, Acid Orange 10, and Acid Violet 19 were subjected to Fenton/Fenton‐like oxidation and its combination with lime coagulation. The analysis indicated no dependence of chemical oxidation efficacy on dye concentration in the range of 0.1–1 g L^?1. Complete or nearly complete (higher than 95%) color removal of all treated samples was observed. Dye:H₂O₂ weight ratio of 1∶2 proved optimal for treatment of all dye solutions by means of Fenton/Fenton‐like oxidation. Moderate doses of hydrogen peroxide led to the improvement of biodegradability of dye solutions. No formation of any toxic intermediates during the oxidation of Acid Orange 10 and Acid Violet 19 was detected. Only a slight toxicity increase was observed after Acid Blue 74 degradation by Fenton chemistry. H₂O₂/Fe³⁺ system with pH adjusted to 3 proved the most effective oxidation process. The combination of Fenton chemistry and subsequent lime coagulation was the most feasible treatment method of removing COD and UV₂₅₄ and UV_max absorbance of dye solutions. Combined oxidation and coagulation was more effective for Acid Blue 74 and Acid Orange 10 elimination than for Acid Violet 19.     

The feasibility of using combined Fenton-SBR for antibiotic wastewater treatment

The first part of this study examined the effect of operating conditions on Fenton pretreatment of an antibiotic wastewater containing amoxicillin and cloxacillin. The optimum H₂O₂/COD and H₂O₂/Fe²⁺ molar ratios were 2.5 and 20, respectively. Under the optimum operating conditions, complete degradation of the antibiotics occurred in 1 min. In the second part of this study, a bench-scale SBR was operated for 239 days and fed with Fenton-treated wastewater under different operating conditions. BOD₅/COD ratio below 0.40 of the Fenton-treated wastewater had negative effect on the SBR performance. Hydraulic retention time (HRT) of 12 h was found suitable for the SBR and increasing HRT to 24 and 48 h did not significantly improve the SBR efficiency. Statistical analysis (two-way ANOVA) was made on the results to optimize the H₂O₂/Fe²⁺ molar ratio and Fenton reaction time and it was found possible to reduce the Fe²⁺ dose and increase the Fenton reaction time. Under the best operating conditions (H₂O₂/COD molar ratio 2.5, H₂O₂/Fe²⁺ molar ratio 150, Fenton reaction time 120 min and HRT 12 h), the combined Fenton-SBR process efficiency was 89% for sCOD removal and the SBR effluent met the discharge standards. Combined Fenton-SBR is a feasible process for antibiotic wastewater treatment.     

Advanced oxidation of cork‐processing wastewater using Fenton's reagent: kinetics and stoichiometry

This work evaluates Fenton oxidation for the removal of organic matter (COD) from cork‐processing wastewater. The experimental variables studied were the dosages of iron salts and hydrogen peroxide. The COD removal ranged from 17% to 79%, depending on the reagent dose, and the stoichiometric reaction coefficient varied from 0.08 to 0.43 g COD (g H₂O₂)^?1 (which implies an efficiency in the use of hydrogen peroxide varying from 17% to 92%). In a study of the process kinetics, based on the initial rates method, the COD elimination rate was maximum when the molar ratio [H₂O₂]_o:[Fe²⁺]_o was equal to 10. Under these experimental conditions, the initial oxidation rate was 50.5 mg COD dm^?3 s^?1 with a rate of consumption of hydrogen peroxide of 140 mg H₂O₂ dm^?3 s^?1, implying an efficiency in the use of the hydrogen peroxide at the initial time of 77%. The total amount of organic matter removed by Fenton oxidation was increased by spreading the H₂O₂ and ferrous salt reagent over several fractions by 15% for two‐fractions and by 21% for three‐fractions. Copyright © 2004 Society of Chemical Industry     

Phenol Removal through Chemical Oxidation using Fenton Reagent

In this study, phenol, aromatic, and non‐biodegradable organic matter were investigated and found to be removed from the model solution through chemical oxidation using Fenton reagent. The effects of the initial phenol concentration, hydrogen peroxide, and ferrous sulfate concentrations on the removal efficiency were investigated. Performance of the chemical oxidation process was monitored with phenol and COD (Chemical Oxygen Demand) analyses. In the experimental studies, phenol removal of over 98 % and COD removal of nearly 70 % were achieved. The optimum conditions for Fenton reaction both for initial phenol concentrations of 200 and 500 mg/L were found at a ratio [Fe²⁺]/[H₂O₂] (mol/mol) equal to 0.11. According to the results, chemical oxidation using Fenton reagent was found to be too effective, especially for phenol removal. However, this method has limited removal efficiency for COD.     

Textile wastewater treatment efficiency by Fenton oxidation with integration of membrane separation system

This work investigates the performance of an integrated Fenton-Ultrafiltration treatment scheme to treat textile wastewater. The treated effluent is particle-free at a quality higher than that obtained by any novel membrane based process or Fenton oxidation in singularity. The study is divided into three parts: part one, Fenton process was optimized for COD: H₂O₂ (wt/wt), H₂O₂: Fe⁺² (wt/wt) and pH to attain highest degradation removal and lowest sludge generation. The process efficiency was analyzed by considering COD, TOC and color removal as key parameters. Part two, the process was scaled up to 5?L and efficiency of integrated system was investigated under optimized conditions by using two different types of membranes at different operating pressures. Part three, the performance of membrane process was studied in terms of flux behavior and its recovery. The treated effluent has COD, TOC and color removal values of 48.0?mg/L, 1.2?mg/L and >99% respectively. These values are compliant to typical discharge environmental standards.     

Ecotoxicological evaluation of a fish farming effluent treated by Fenton oxidation and coagulation process

ABSTRACT

This study has evaluated the efficiency of Fenton process followed by coagulation to treat real effluent from fish farm. Fenton obtained Chemical Oxygen Demand and turbidity removal of 48% at (0.5 mg L^?1 Fe²⁺ and 10 mmol H₂O₂). Fenton followed by coagulation reduced COD and turbidity by almost 100%. The process also decreased the concentrations of suspended solids, phosphate, nitrate, Biological Oxygen Demand, and nitrite. Ecotoxicology test indicated that the effluent treated with 0.5 mmol L^?1 Fe²⁺ in 10 mmol L^?1 H₂O₂ displayed the lowest toxicity. These findings can indicate an environmental friendly alternative to treat fish farm effluent.     

Study of phenol removal using fluidized-bed Fenton process

In this paper, the removal of phenol from simulated wastewater was studied using gas–liquid fluidized bed with the Fenton reagent. The factors that affect the removal rate of phenol were investigated, including the initial concentrations of hydrogen peroxide [H₂O₂] and [Fe²⁺], the molar ratio of [Fe²⁺]/[H₂O₂], pH value, temperatures, reaction time, and the ventilation volume. It was found that the optimal operating conditions existed as: [H₂O₂] = 12 mmol/L, [H₂O₂]/[Fe²⁺] = 4:1, pH = 4, T = 60 °C, reaction time of 30 min, and a ventilation volume of 0.12 m³/h. Under these conditions, the phenol removal rate of about 96% was obtained.     

Stabilization and dewatering of wastewater treatment plant sludge using combined bio/Fenton-like oxidation process

Wastewater sludge usually contains large amounts of water and organic materials; therefore, its stabilization and dewatering are of particular importance. The present study aimed to investigate the possibility of sludge stabilization and dewatering from wastewater sludge by bioleaching (Thiobacillus ferrooxidans), Fenton/bioleaching, and bioleaching/Fenton-like processes. To evaluate sludge stabilization and dewatering, specific resistance to filtration (SRF), volatile suspended solids (VSS), total suspended solids (TSS), and soluble chemical oxygen demand (SCOD) were measured. In biological treatment with T. ferrooxidans with Fe²⁺ (2?g?L^?1), 99.75, 33, 37, and 72% reduction were observed in SRF, VSS, TSS, SCOD, respectively, after 2 days. In the combined treatment of Fenton before bioleaching (including Fe²⁺ 2?g?L^?1 and H₂O₂ 1?g?L^?1 with Fenton oxidation for 30?min followed by biological treatment with T. ferrooxidans for 2 days), the reduction rates in TSS, VSS, SCOD, and SRF were 40.18, 40.88, 60.95, and 75.43%, respectively. In treatment with the combined method of bioleaching before Fenton-like oxidation, the removal rates of the aforementioned parameters were 52.5, 54.4, 88, and 99.82%, respectively. In comparison to Fenton oxidation and bioleaching alone, combined biological method of bioleaching/Fenton-like oxidation using a lower dose of H₂O₂ and Fe²⁺ significantly improved sludge dewatering and stabilization.     

Removal of metsulfuron methyl by Fenton reagent

The removal of metsulfuron methyl (MeS)—a sulfonyl urea herbicide from contaminated water was investigated by advanced oxidation process (AOP) using Fenton method. The optimum dose of Fenton reagent (Fe²⁺/H₂O₂) was 10 mg/L Fe²⁺ and 60 mg/L H₂O₂ for an initial MeS concentration ([MeS]₀) range of 0–80 mg/L. The Fenton process was effective under pH 3. The degradation efficiency of MeS decreased by more than 70% at pH > 3 (pH 4.5 and 7). The initial Fe²⁺ concentration ([Fe²⁺]₀) in the Fenton reagent affected the degradation efficiency, rate and kinetics. The degradation of MeS at optimum dose of Fenton reagent was more than 95% for [MeS] ₀ of 0–40 mg/L and the degradation time was less than 30 min. The determination of residual MeS concentration after Fenton oxidation by UV spectrophotometry was affected by the interferences from Fenton reagent. The estimation of residual MeS concentration after Fenton oxidation by high pressure/performance liquid chromatograph (HPLC) was interference free and represented the actual concentration of MeS and does not include the by-products of Fenton oxidation. The degradation kinetics of MeS was modelled by second order reactions involving 8 rate constants. The two reaction constants directly involving MeS were fitted using the experimental data and the remaining constants were selected from previously reported values. The model fit for MeS and the subsequent prediction of H₂O₂ were found to be within experimental error tolerances.     

Optimization of Fenton process for refinery wastewater biodegradability augmentation

The Fenton process was used to increase the biodegradability of refinery wastewater. Initially, effects of reaction time, H₂O₂/COD and H₂O₂/Fe²⁺ molar ratios were investigated and biodegradability of wastewater was determined in terms of the BOD₅/COD ratio. Preliminary results showed that the Fenton process was able to improve wastewater biodegradability from 0.27 to 0.43. Subsequently, the process was optimized by using response surface methodology based on a five-level central composite design. Adequacy and significance of results were analyzed in analysis of variance. The quadratic model was found to be significant to give less than 0.05 probability of error. The model was fit with data based on insignificant of lack-of-fit test at values of 0.93. The high R² and Adj.R² (0.95 and 0.91) indicates satisfactory adjustment of quadratic model to experimental data. Based on optimized conditions, wastewater biodegradability improved to 0.44 via H₂O₂/COD and H₂O₂/Fe²⁺ molar ratios of 2.8 and 4 within 71 minutes reaction time.     

亚甲基蓝光度法研究基于CaO2的Fenton反应条件

CaO₂作为原位Fenton 氧化修复中H₂O₂持续供源的作用逐渐受到关注。利用亚甲基蓝分光光度法评价了基于CaO₂的Fenton反应中催化剂种类、初始pH值、CaO₂用量、催化剂和CaO₂比例、磷酸缓冲溶液浓度对羟基自由基（HO·）产率的影响。结果表明,采用Fe²⁺作为催化剂,在pH值为4、CaO₂相似文献   

Photo Assisted Fenton in a Batch and a Membrane Reactor for Degradation of Drugs in Water

Abstract

Some advanced oxidation processes (AOP's) such as Fenton H₂O₂/Fe²⁺, photo assisted Fenton UV/H₂O₂/Fe²⁺, UV photolysis, and photo assisted Fenton—like UV/O₂/Fe²⁺ have been tested for the degradation of Gemfibrozil in aqueous solution in a batch system and then in a membrane reactor. A nanofiltration/reverse osmosis type cross‐linked polyamide, UTC‐60 (Toray) membrane (19 cm²) was used. In the batch degradation tests, the gemfibrozil, used at 5 mg/L, was degraded by employing the four AOP's but numerous peaks of intermediates were observed at the HPLC. Indeed DOC analyses showed poor mineralization in the case of photolysis (3.1%) and UV/O₂/Fe (10%), while it was 62% using the photo assisted Fenton and 24% using the Fenton. Thus in the membrane reactor only the Fenton and the photo assisted Fenton were tested. Obtained results showed a drug degradation higher than 92%, a mineralization higher than 55%, and a membrane retention of the catalyst in solution higher than 95%.     

Advanced Oxidative Removal of Nitric Oxide from Flue Gas by Homogeneous Photo‐Fenton in a Photochemical Reactor

In this work, advanced oxidation removal of nitric oxide (NO) from flue gas by homogeneous Photo‐Fenton was investigated in a photochemical reactor and the effects of several influencing factors on NO removal were evaluated. The gas‐liquid reaction products were determined. The reaction pathways of NO removal are also preliminarily discussed. It was found that with the increase of Fe²⁺ concentration, NO removal efficiency first increased and then decreased. Increasing H₂O₂ concentration and UV radiation intensity greatly increased NO removal efficiency, but the growth rates gradually became smaller. NO removal efficiency greatly reduced with the increase of gas flow and NO concentration, and only slightly decreased with the increase of solution temperature, but significantly increased with the increase of initial solution pH value. The main anion product in the liquid phase was NO₃^–. With respect to removal of NO using homogeneous Photo‐Fenton, ·OH oxidation was the main reaction pathway, and H₂O₂ oxidation was the secondary reaction pathway.     

The sonochemical decolorisation of textile azo dye CI Reactive Orange 127

In the present study, Fenton and sono‐Fenton processes were applied to the oxidative decolorisation of synthetic textile wastewater including CI Reactive Orange 127 and polyvinyl alcohol. Process optimisation [pH, ferrous ion (Fe²⁺) and hydrogen peroxide (H₂O₂)], kinetic studies and their comparison were carried out for both of the processes. The sono‐Fenton process was performed by indirect sonication in an ultrasonic water bath, which was operated at a fixed 35‐kHz frequency and 80 W power. The optimum conditions were determined as [Fe²⁺] = 20 mg l^?1, [H₂O₂] = 15 mg l^?1 and pH = 3 for the Fenton process and [Fe²⁺] = 25 mg l^?1, [H₂O₂] = 5 mg l^?1 and pH = 3 for the sono‐Fenton process. The colour removals were 89.9% and 91.8% by the Fenton and sono‐Fenton processes, respectively. The highest decolorisation was achieved by the sono‐Fenton process because of the production of some oxidising agents as a result of sonication. Consequently, ultrasonic irradiation in the sono‐Fenton process slightly increased the colour removal to 91.8%, while decreasing the hydrogen peroxide dosage to one‐third of that of the Fenton process.     

Gaseous Elemental Mercury Removal Using Combined Metal Ions and Heat Activated Peroxymonosulfate/H2O2 Solutions

Several novel oxidation removal processes of elemental mercury (Hg⁰) from flue gas using combined Fe²⁺/Mn²⁺ and heat activated peroxymonosulfate (PMS)/H₂O₂ solutions in a bubbling reactor were proposed. The operating parameters (e.g., PMS/H₂O₂ concentration, Fe²⁺/Mn²⁺ concentration, solution pH, activation temperature, and Hg⁰/NO/SO₂/O₂/CO₂ concentration), mechanism and mass transfer-reaction kinetics of Hg⁰ removal were investigated. The results show that heat and Fe²⁺/Mn²⁺ have significant synergistic effect for activating PMS and PMS/H₂O₂ to produce free radicals to oxidize Hg⁰. Hg⁰ removal is strongly affected by PMS/H₂O₂ concentration, Fe²⁺/Mn²⁺ concentration, activation temperature, and solution pH. · and ·OH produced from combined heat and Fe²⁺/Mn²⁺ activated PMS/H₂O₂ play a leading role in Hg⁰ removal. Under optimized experimental conditions, Hg⁰ removal efficiencies reach 100, 94.9, 66.9, and 58.9% in heat/Fe²⁺/PMS/H₂O₂, heat/Mn²⁺/PMS/H₂O₂, heat/Fe²⁺/PMS, and heat/Mn²⁺/PMS systems, respectively. Hg⁰ removal processes in four systems belong to fast reaction and were controlled by mass transfer under optimized experimental conditions. © 2018 American Institute of Chemical Engineers AIChE J, 65: 161–174, 2019     

The optimization of the photo-oxidation parameters to remediate wastewater from the textile dyeing industry in a continuous stirred tank reactor

The remediation of textile dying wastewater was carried out at ambient temperatures in a pilot-scale continuous stirred tank reactor by using the photo-Fenton oxidation process. The preliminary results suggest that the treatment system reached a steady state condition within 5–10 min after it was started up. By using a 2 ^k factorial design, the effects of various parameters on the removal efficiency of color, BOD and COD were identified under steady state conditions. The removal efficiencies of color and BOD were affected by the feed rate of H₂O₂ and Fe²⁺, whereas none of the parameters in the investigated ranges affected the removal efficiency of COD. Consequently, using univariate analysis to investigate higher parameter range values, the optimum conditions for treating textile wastewater were found to be 25 ml H₂O₂/min, 5 ml Fe²⁺/min and 90 W UV-A power for 20 min. In addition, the removal of all pollutants was enhanced within the acidic pH range. Approximately 69.2, 99.4 and 48.5% of color, BOD and COD were removed, respectively. However, the concentration of TDS increased slightly during the treatment period due to the formation of new species or intermediate oxidation products. Nevertheless, all values of pollutants in the treated wastewater except COD were in the range of the standard values permitted for discharge into the environment.     

Mercury removal from coal combustion by Fenton reactions – Part A: Bench-scale tests

This series of papers describes the development of technology to convert Hg(0) to Hg(II) in coal-derived flue gas based on the well-known Fenton reactions so that a Hg control strategy can be implemented in a wet scrubber. This effort consists of both bench-scale and pilot-scale work. This first paper reports on the bench-scale tests. The bench-scale results showed that Hg(0) oxidation can be achieved by the Fenton reactions and the oxidation rate is quantitatively dependent on the residence time of the Hg stream in the solution. An average of 75% oxidation of Hg(0) was achieved. Iron-based Fenton-type additives gave much more promising results compared to Cu-based Fenton-like additives for Hg(0) oxidation. The pH value of the sorbent solution also had a significant effect on the oxidation of Hg(0) and a suitable pH window was found to lie between 1.0 and 3.0 for this application. This may be attributed to the chain reaction mechanisms of Fe³⁺/H₂O₂ for Fenton reactions, i.e., the decomposition of H₂O₂ for the production of OOH radicals in the Fe³⁺/H₂O₂ system which is kinetically favoured under a wide range of conditions at pH values of 3 or less. At higher pH values, H₂O₂ is converted to H₂O instead of OOH radicals in the presence of Fe³⁺.     

Chelate-modified fenton treatment of sulfidic spent caustic

Spent caustic can be treated by several treatment methods. Among the advanced techniques, Fenton reagent has many advantages. But since spent caustic contains excessive amounts of sulfide compounds, utilizing this technique in treatment of such wastewaters is not economical. The acid neutralization step, which was applied as the pretreatment process, showed an 84% COD abatement at temperature equal to 80 °C and a pH equal to 4.0. The acid neutralized wastewater was then introduced to the chelate-modified Fenton system and oxidized. Using a ratio of tartrate/Fe²⁺=1.1, reaction time=50min, temperature=95 °C, Fe²⁺=110mg/l and a ratio of H₂O₂/COD=1.2 in the chelate-modified Fenton system at an optimum pH value equal to 1.9, total COD abatement of the wastewater reached over 99.4%. Having tartrate added to the Fenton system, a series of photochemical reactions enhanced Fe²⁺ and hydroxyl radicals’ generation. This method has proved to be the recommended technique for the contamination abatement of spent caustic.