Application of Fenton oxidation to cosmetic wastewaters treatment

The removal of organic matter (TOC and COD) from a cosmetic wastewater by Fenton oxidation treatment has been evaluated. The operating conditions (temperature as well as ferrous ion and hydrogen peroxide dosage) have been optimized. Working at an initial pH equal to 3.0, a Fe(2+) concentration of 200 mg/L and a H(2)O(2) concentration to COD initial weight ratio corresponding to the theoretical stoichiometric value (2.12), a TOC conversion higher than 45% at 25 degrees C and 60% at 50 degrees C was achieved. Application of the Fenton oxidation process allows to reach the COD regional limit for industrial wastewaters discharges to the municipal sewer system. A simple kinetic analysis based on TOC was carried out. A second-order equation describes well the overall kinetics of the process within a wide TOC conversion range covering up to the 80-90% of the maximum achievable conversion.     

Optimization of Fenton process for the treatment of landfill leachate

The treatment of landfill leachate by Fenton process was carried out in a batch reactor. The effect of operating conditions such as reaction time, pH, H2O2 to Fe(II) molar ratio, Fenton's reagent dosage, initial COD strength, feeding mode, the type of polymer, and temperature on the efficacy of Fenton process was investigated. It is demonstrated that Fenton's reagent can effectively degrade leachate organics. Fenton process was so fast that it was complete in 30 min. The oxidation of organic materials in the leachate was pH dependent and the optimal pH was 2.5. The favorable H2O2 to Fe(II) molar ratio was 1.5, and organic removal increased as dosage increased at the favorable H2O2 to Fe(II) molar ratio. The efficacy of Fenton process was improved by adding Fenton's reagent in multiple steps than that in a single step. Furthermore, the stepwise addition of both hydrogen peroxide and ferrous iron was more effective than that of hydrogen peroxide only. Sludge settling characteristics were much improved with the addition of the proper polymer. Temperature gave a positive effect on organic removal.     

Pre-treatment of penicillin formulation effluent by advanced oxidation processes

A variety of advanced oxidation processes (AOPs; O3/OH-, H2O2/UV, Fe2+/H2O2, Fe3+/H2O2, Fe2+/H2O2/UV and Fe3+/H2O2/UV) have been applied for the oxidative pre-treatment of real penicillin formulation effluent (average COD0 = 1395 mg/L; TOC0 = 920 mg/L; BOD(5,0) approximately 0 mg/L). For the ozonation process the primary involvement of free radical species such as OH* in the oxidative reaction could be demonstrated via inspection of ozone absorption rates. Alkaline ozonation and the photo-Fenton's reagents both appeared to be the most promising AOPs in terms of COD (49-66%) and TOC (42-52%) abatement rates, whereas the BOD5 of the originally non-biodegradable effluent could only be improved to a value of 100 mg/L with O3/pH = 3] treatment (BOD5/COD, f = 0.08). Evaluation on COD and TOC removal rates per applied active oxidant (AOx) and oxidant (Ox) on a molar basis revealed that alkaline ozonation and particularly the UV-light assisted Fenton processes enabling good oxidation yields (1-2 mol COD and TOC removal per AOx and Ox) by far outweighed the other studied AOPs. Separate experimental studies conducted with the penicillin active substance amoxicillin trihydrate indicated that the aqueous antibiotic substance can be completely eliminated after 40 min advanced oxidation applying photo-Fenton's reagent (pH = 3; Fe(2+):H2O2 molar ratio = 1:20) and alkaline ozonation (at pH = 11.5), respectively.     

Integrated treatment of olive mill wastewater (OMW) by the combination of Fenton's reaction and anaerobic treatment

The use of an integrated treatment scheme consisting of wet hydrogen peroxide catalytic oxidation (WHPCO) followed by two-stage upflow anaerobic sludge blanket (UASB) reactor (10l each) for the treatment of olive mill wastewater was the subject of this study. The diluted wastewater (1:1) was pre-treated using Fenton's reaction. Optimum operating conditions namely, pH, H(2)O(2) dose, Fe(+2), COD:H(2)O(2) ratio and Fe(+2):H(2)O(2) ratio were determined. The UASB reactor was fed continuously with the pre-treated wastewater. The hydraulic retention time was kept constant at 48h (24h for each stage). The conventional parameters such as COD, BOD, TOC, TKN, TP, TSS, oil and grease, and total phenols were determined. The concentrations of polyphenolic compounds in raw wastewater and effluents of each treatment step were measured using HPLC. The results indicated a good quality final effluent. Residual concentrations of individual organic compounds ranged from 0.432 mg l(-1) for rho-hydroxy-benzaldhyde to 3.273 mg l(-1) for cinnamic acid.     

A kinetic study on the degradation of p-nitroaniline by Fenton oxidation process

A detailed kinetic model was developed for the degradation of p-nitroaniline (PNA) by Fenton oxidation. Batch experiments were carried out to investigate the role of pH, hydrogen peroxide and Fe(2+) levels, PNA concentration and the temperature. The kinetic rate constants, k(ap), for PNA degradation at different reaction conditions were determined. The test results show that the decomposition of PNA proceeded rapidly only at pH value of 3.0. Increasing the dosage of H(2)O(2) and Fe(2+) enhanced the k(ap) of PNA degradation. However, higher levels of H(2)O(2) also inhibited the reaction kinetics. The k(ap) of PNA degradation decreased with the increase of initial PNA concentration, but increased with the increase of temperature. Based on the rate constants obtained at different temperatures, the empirical Arrhenius expression of PNA degradation was derived. The derived activation energy for PNA degradation by Fenton oxidation is 53.96 kJ mol(-1).     

Use of Fenton oxidation to improve the biodegradability of a pharmaceutical wastewater

The applicability of Fenton's oxidation to improve the biodegradability of a pharmaceutical wastewater to be treated biologically was investigated. The wastewater was originated from a factory producing a variety of pharmaceutical chemicals. Treatability studies were conducted under laboratory conditions with all chemicals (having COD varying from 900 to 7000 mg/L) produced in the factory in order to determine the operational conditions to utilize in the full-scale treatment plant. Optimum pH was determined as 3.5 and 7.0 for the first (oxidation) and second stage (coagulation) of the Fenton process, respectively. For all chemicals, COD removal efficiency was highest when the molar ratio of H(2)O(2)/Fe(2+) was 150-250. At H(2)O(2)/Fe(2+) ratio of 155, 0.3M H(2)O(2) and 0.002 M Fe(2+), provided 45-65% COD removal. The wastewater treatment plant that employs Fenton oxidation followed by aerobic degradation in sequencing batch reactors (SBR), built after these treatability studies provided an overall COD removal efficiency of 98%, and compliance with the discharge limits. The efficiency of the Fenton's oxidation was around 45-50% and the efficiency in the SBR system which has two reactors each having a volume of 8m(3) and operated with a total cycle time of 1 day, was around 98%, regarding the COD removal.     

Olive mill wastewater degradation by Fenton oxidation with zero-valent iron and hydrogen peroxide

The degradation of olive mill wastewater (OMW) with hydroxyl radicals generated from zero-valent iron and hydrogen peroxide has been investigated by means of chemical oxygen demand (COD) and phenolic compounds analyses. The effects of the H2O2 dose, the pH and the organic matter concentration have been studied. The optimal experimental conditions were found to have continuous presence of iron metal, acid pH (2.0-4.0), and relatively concentrated hydrogen peroxide (9.5M). Coloration of OMW disappeared and phenolic compound decreased to 50% of initial concentration after 3h reaction time. The application of zero-valent Fe/H2O2 procedure permitted high removal efficiencies of pollutants from olive mill wastewater. The results show that zero-valent Fe/H2O2 could be considered as an effective alternative solution for the treatment of OMW or may be combined with a classical biological process to achieve high quality of effluent water.     

Treatment of landfill leachate by Fenton's reagent in a continuous stirred tank reactor

The treatment of landfill leachate by Fenton process was carried out in a continuous stirred tank reactor (CSTR). The effect of operating conditions such as reaction time, hydraulic retention time, pH, H(2)O(2) to Fe(II) molar ratio, Fenton's reagent dosage, initial COD strength, and temperature on the efficacy of Fenton process was investigated. It is demonstrated that Fenton's reagent can effectively degrade leachate organics. Fenton process reached the steady state after three times of hydraulic retention. The oxidation of organic materials in the leachate was pH dependent and the optimal pH was 2.5. The favorable H(2)O(2) to Fe(II) molar ratio was 3, and organic removal increased as dosage increased at the favorable H(2)O(2) to Fe(II) molar ratio. Temperature gave a positive effect on organic removal.     

Kinetics of 2,6-dimethylaniline degradation by electro-Fenton process

A new approach for promoting ferric reduction efficiency using a different electrochemical cell and the photoelectro-Fenton process has been developed to degrade organic toxic contaminants. The use of UVA light and electric current as electron donors can efficiently initiate the Fenton reaction. 2,6-Dimethylaniline (2,6-DMA) was the target compound in this study. Effects of initial pH (pH(i)), Fe(2+) loading, H(2)O(2) concentration and current density were determined to test and to validate a kinetic model for the oxidation of organic compound by the electro-Fenton process. Kinetic results show evidence of pseudo-first-order degradation. When reaction pH was higher than 2, amorphous Fe(OH)(3(s)) was generated. Increasing ferrous ion concentration from 1.0 to 1.5 mM increased the hydroxyl radicals and then promote the degradation efficiency of 2,6-DMA. The optimal H(2)O(2) concentration for 2,6-DMA degradation in this study was 25 mM. The degradation of 2,6-DMA was increased with the increase of current density from 3.5 to 10.6 A/m(2). Oxalic acid was the major detected intermediate of 2,6-DMA degradation. The final TOC removal efficiencies were 10%, 15%, 60% and 84% using the electrolysis, Fenton, electro-Fenton and photoelectro-Fenton processes, respectively.     

Kinetic and mechanistic investigations of mesotrione degradation in aqueous medium by Fenton process

In this work, chemical oxidation of mesotrione herbicide by Fenton process in acidic medium (pH 3.5) was investigated. Total disappearance of mesotrione and up to 95% removal of total organic carbon (TOC) were achieved by Fenton's reagent under optimized initial concentrations of hydrogen peroxide (H(2)O(2)) and ferrous iron (Fe(2+)) at pH 3.5. The time-dependent degradation profiles of mesotrione were satisfactorily fitted by first-order kinetics. Competition kinetic model was used to evaluate a rate constant of 8.8(± 0.2) × 10(9)M(-1) s(-1) for the reaction of mesotrione with hydroxyl radicals. Aromatic and aliphatic intermediates of mesotrione oxidation were identified and quantified by high performance liquid chromatography (HPLC). It seems that the degradation of mesotrione by Fenton process begins with the rupture of mesotrione molecule into two moieties: cyclohexane-1,3-dione derivative and 2-nitro-4-methylsulfonylbenzoic acid. Hydroxylation and release of sulfonyl and/or nitro groups from 2-nitro-4-methylsulfonylbenzoic acid lead to the formation of polyhydroxylated benzoic acid derivatives which undergo an oxidative opening of benzene ring into carboxylic acids that end to be transformed into carbon dioxide.     

A simple methodology to evaluate influence of H2O2 and Fe(2+) concentrations on the mineralization and biodegradability of organic compounds in water and soil contaminated with crude petroleum

Simple measurements of H2O2 concentration or CO2 evolution were used to evaluate the effectiveness of the use of Fenton's reagent to mineralize organic compounds in water and soil contaminated by crude petroleum. This methodology is suitable for application in small treatment and remediation facilities. Reagent concentrations of H2O2 and Fe(2+) were found to influence the reaction time and temperature, as well as the degree of mineralization and biodegradability of the sample contaminants. Some H2O2/Fe(2+) combinations (H2O2 greater than 10% and Fe(2+) greater than 50mM) resulted in a strong exothermic reaction, which causes peroxide degradation and violent gas liberation. Up to 75% TOC removal efficiency was attained in water and 70% in soil when high H2O2 (20%) and low Fe(2+) (1mM) concentrations were used. Besides increasing the degree of mineralization, the Fenton's reaction enhances the biodegradability of petroleum compounds (BOD5/COD ratios) by a factor of up to 3.8 for contaminated samples of both water and soil. Our experiments showed that low reagent concentrations (1% H2O2 and 1mM Fe(2+)) were sufficient to start the degradation process, which could be continued using microorganisms. This leads to a decrease in reagent costs in the treatment of petroleum-contaminated water and soil samples. The simple measurements of H2O2 concentration or CO2 evolution were effective to evaluate the Fenton's reaction efficiency.     

Removal and degradation pathway study of sulfasalazine with Fenton-like reaction

The Fenton-like degradation of sulfasalazine solution is studied in this work. The effects of reaction parameters such as Fe(3+) concentration, initial H(2)O(2) dosage and the reaction temperature are evaluated. For sulfasalazine of 100mg/L, the removal of sulfasalazine, chemical oxygen demand (COD) and total organic carbon (TOC) reached 99.5%, 84.2% and 41% in 60 min with 0.20mM Fe(3+) and 16 mM H(2)O(2) at 35°C, respectively. The complexed Fe(3+) presents a reaction constant of 0.062 min(-1)mM(-1) while that of free Fe(3+) is 2.526 min(-1)mM(-1) for sulfasalazine degradation. LC-MS technology was used to analysis the possible degradation intermediates. The degradation of sulfasalazine principally begins with the attack of hydroxyl radical on the azo-group as well as the sulfanilamido group. Both intramolecular rearrangement and bimolecular reaction occur simultaneously after the hydroxyl radical attack. Further attack of the active oxidative species results in the cleavage of the aromatic rings and the production of CO(2). The degradation of industrial sulfasalazine wastewater with a COD of 3425 mg/L has also been achieved by Fenton reaction with different dosage of H(2)O(2). Relatively better removal efficiency is observed at moderate Fe/H(2)O(2) molar ratio from 1/5 to 2/5 for industrial sulfasalazine wastewater treatment.     

Photo-Fenton process as an efficient alternative to the treatment of landfill leachates

Advanced oxidation processes (AOPs), namely photo-Fenton, Fenton-like, Fenton and UV/H(2)O(2), have been investigated in the removal of organic matter and colour from landfill leachates. The leachate was characterised by high COD, low biodegradability and intense dark colour. Evaluation of COD removal as a function of the operation variables (H(2)O(2), Fe(2+), Cu(2+), UV) led to results that ranged between 30% and 77% and it was observed that the removal efficiencies decreased in the order: photo-Fenton>Fenton-like>Fenton>UV/H(2)O(2)>UV. Thus, a detailed experimental analysis was carried out to analyse the effect of the hydrogen peroxide and iron concentrations and the number of reagent additions in the photo-Fenton process, observing that: (i) the COD removal ranged from 49% to 78% depending on the H(2)O(2) dose, (ii) the total amount of organic matter removed was increased by adding the reagent in multiple steps (86%), (iii) iron concentration corresponding to a Fe(2+)/COD mass ratio=0.33 was found to be the most favourable and, (iv) after a neutralization step, the colour and residual concentrations of iron and H(2)O(2) were practically negligible in the final leachate solution.     

A comparative study among different photochemical oxidation processes to enhance the biodegradability of paper mill wastewater

Advanced oxidation processes including UV, UV/H(2)O(2), Fenton reaction (Fe(II)/H(2)O(2)) and photo-Fenton process (Fe(II)/H(2)O(2)/UV) for the treatment of paper mill wastewater will be investigated. A comparison among these techniques is undertaken with respect to the decrease of chemical oxygen demand (COD) and total suspended solids (TSS) and the evolution of chloride ions. Optimum operating conditions for each process under study revealed the effect of the initial amounts of Fe(II) and hydrogen peroxide. Of the tested processes, photo-Fenton process was found to be the fastest one with respect to COD and TSS reduction of the wastewater within 45 min reaction time under low amounts of Fe(II) and hydrogen peroxide of 0.5 and 1.5mg/L, respectively, and amounted to 79.6% and 96.6% COD and TSS removal. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD(5)/COD, was low 0.21. When the effluent was submitted to the different types of AOPs used in this study, the biodegradability increases significantly. Within 45 min of reaction time, the photo-Fenton process appears as the most efficient process in the enhancement of the biodegradability of the organic matter in the effluent and the BOD(5)/COD ratio increased from 0.21 to 0.7.     

Photo-assisted Fenton type processes for the degradation of phenol: a kinetic study

In this study the application of advanced oxidation processes (AOPs), dark Fenton and photo-assisted Fenton type processes; Fe(2+)/H(2)O(2), Fe(3+)/H(2)O(2), Fe(0)/H(2)O(2), UV/Fe(2+)/H(2)O(2), UV/Fe(3+)/H(2)O(2) and UV/Fe(0)/H(2)O(2), for degradation of phenol as a model organic pollutant in the wastewater was investigated. A detail kinetic modeling which describes the degradation of phenol was performed. Mathematical models which predict phenol decomposition and formation of primary oxidation by-products: catechol, hydroquinone and benzoquinone, by applied processes were developed. The study also consist the modeling of mineralization kinetic of the phenol solution by applied AOPs. This part, besides well known reactions of Fenton and photo-Fenton chemistry, involves additional reactions which describe removal of iron from catalytic cycle through formation of ferric complexes and its regeneration induced by UV radiation. Phenol decomposition kinetic was monitored by HPLC analysis and total organic carbon content measurements (TOC). Complete phenol removal was obtained by all applied processes. Residual TOC by applied Fenton type processes ranged between 60.2 and 44.7%, while the efficiency of those processes was significantly enhanced in the presence of UV light, where residual TOC ranged between 15.2 and 2.4%.     

Color, TOC and AOX removals from pulp mill effluent by advanced oxidation processes: a comparative study

Pulp mill effluent containing toxic chemicals was treated by different advanced oxidation processes (AOPs) consisting of treatments by hydrogen peroxide, Fenton's reagent (H2O2/Fe2+), UV, UV/H2O2, photo-Fenton (UV/H2O2/Fe2+), ozonation and peroxone (ozone/H2O2) in laboratory-scale reactors for color, total organic carbon (TOC) and adsorbable organic halogens (AOX) removals from the pulp mill effluent. Effects of some operating parameters such as the initial pH, oxidant and catalyst concentrations on TOC, color, AOX removals were investigated. Almost every method used resulted in some degree of color removal from the pulp mill effluent. However, the Fenton's reagent utilizing H2O2/Fe2+ resulted in the highest color, TOC and AOX removals under acidic conditions when compared with the other AOPs tested. Approximately, 88% TOC, 85% color and 89% AOX removals were obtained by the Fenton's reagent at pH 5 within 30 min. Photo-Fenton process yielded comparable TOC (85%), color (82%) and AOX (93%) removals within 5 min due to oxidations by UV light in addition to the Fenton's reagent. Fast oxidation reactions by the photo-Fenton treatment makes this approach more favorable as compared to the others used.     

Physical and oxidative removal of organics during Fenton treatment of mature municipal landfill leachate

Municipal landfill leachate, especially mature leachate, may disrupt the performance of moderately-sized municipal activated sludge wastewater treatment plants, and likewise tend to be recalcitrant to biological pretreatment. Recently, Fenton methods have been investigated for chemical treatment or pre-treatment of mature leachate. In this paper, the results of laboratory tests to determine the roles of oxidation and coagulation in reducing the organic content of mature leachate during Fenton treatment are presented. The efficiencies of chemical oxygen demand (COD) oxidation and coagulation were tested, and the ratio of COD removal by oxidation to that by coagulation was assessed, under various operating conditions. Low initial pH, appropriate relative and absolute Fenton reagent dosages, aeration, and stepwise addition of reagents increased COD removal by oxidation and the importance of oxidation relative to coagulation. Simultaneous aeration and stepwise reagent addition allowed comparable treatment without initial acidification pH, due to the generation of acidic organic intermediates and the continuous input of CO2. On the other hand, high COD oxidation efficiency and low ferrous dosage inhibited COD removal by coagulation. At significantly high oxidation efficiency, overall COD reduction decrease slightly due to low coagulation efficiency. Under the most favorable conditions (initial pH 3, molar ratio [H(2)O(2)]/[Fe2+]=3, [H2O2]=240 mM, and six dosing steps), 61% of the initial COD was removed, and the ratio of COD removal oxidation to coagulation was 0.75. Results highlighted the synergistic roles of oxidation and coagulation in Fenton treatment of mature leachate, and the role of oxidation in controlling the efficiency of removal of COD by coagulation.     

Importance of H(2)O(2)/Fe(2+) ratio in Fenton's treatment of a carpet dyeing wastewater

The effectiveness of the Fenton's reagent (H(2)O(2)/Fe(2+)) in the treatment of carpet dyeing wastewater was investigated under different operational conditions, namely, H(2)O(2) and FeSO(4) concentrations, initial pH and temperature. Up to 95% COD removal efficiency was attained using 5.5 g/l FeSO(4) and 385 g/l H(2)O(2) at a pH of 3, temperature of 50 degrees C. The H(2)O(2)/Fe(2+) ratio (g/g) was found to be between 95 and 290 for maximum COD removal. It was noteworthy that, keeping H(2)O(2)/Fe(2+) ratio constant within the range of 95-290, it became possible to decrease FeSO(4) concentration to 1.1 g/l and H(2)O(2) concentration to 96.3 g/l, still achieving nearly the same COD removal efficiency. The relative efficiencies of Fenton's oxidation and coagulation stages revealed that Fenton's coagulation removed organic compounds which were not removed by Fenton's oxidation, indicating that the Fenton's coagulation acted as a polishing step.     

Alkydic resin wastewaters treatment by fenton and photo-Fenton processes

Advanced oxidation processes are an emerging option to treatment of the painting industry effluents. The aim of this study was to compare the effectiveness of the Fenton and photo-Fenton processes in chemical oxygen demand (COD), total organic carbon (TOC) and phenolic compounds removal from wastewaters generated during alkydic resins manufacture. The optimized treatment conditions are the following: pH 3.0, 15.15x10(-3)molL(-1) FeSO(4) and 0.30molL(-1) H(2)O(2) for a reaction time of 6h. photo-Fenton experiments were carried out in the presence of sunlight or artificial radiation and complementary additions of H(2)O(2) were made for all experiments. The best results were obtained with photo-Fenton process assisted with solar radiation, with reductions of 99.5 and 99.1% of COD and TOC levels, respectively. Fenton and photo-Fenton (with artificial irradiation) processes presented lower but not insignificant removals, within 60-80% reduction for both COD and TOC. In addition, an excellent removal (95%) of total phenols was obtained using photo-Fenton process assisted with artificial irradiation. This study demonstrated that the use of photo-Fenton process on alkydic resins wastewater treatment is very promising especially when solar light is used.     

A kinetic model for the decolorization of C.I. Acid Yellow 23 by Fenton process

The decolorization of azo dye C.I. Acid Yellow 23 (AY23) by Fenton process was investigated. The decolorization rate is strongly dependent on the initial concentrations of the Fe(2+) and H(2)O(2). The optimum operational conditions were obtained at pH 3. A kinetic model has been developed to predict the decolorization of AY23 at different operational conditions by Fenton process. The model allows to simulate the system behavior involving the influence of hydrogen peroxide, Fe(II) and dye concentrations.