Fenton Pretreatment Research Articles

Comparison of Fenton and bismuth ferrite Fenton-like pretreatments of sugarcane bagasse to enhance enzymatic saccharification

This study compared enzymatic saccharification of sugarcane bagasse (SCB) after application of two different pretreatment methods, Fenton pretreatment (FP) and BiFeO3 Fenton-like pretreatment (BFP). The composition, morphology and structural properties of SCB with different pretreatments were analyzed. Results showed that, after BFP, the yield of reducing sugar of SCB under enzymatic saccharification for 72 h was 25.8%, and the sugar conversion rate was 36.6%, which were 2.2 and 2.4-fold those of the FP, respectively. Moreover, the removal of hemicellulose and delignification in the BFP was more severe than that in the FP. The determination of hydroxyl radical (OH) in the two different Fenton processes revealed that the OH generated in the BiFeO3 Fenton-like system was higher in concentration and longer in action time than that in the Fenton system, which was likely key to the stronger effect of BFP than FP on the enzymatic saccharification of SCB.

Effect of Fenton Pretreatment on C1 and C6 Oxidation of Cellulose and its Enzymatic Hydrolyzability

Cellulose oxidation plays an important role in improving enzymatic hydrolysis by making cellulose more accessible. To determine whether C1 or C6 oxidation in Fenton pretreatment can boost hydrolysi...

Improving dewaterability and filterability of waste activated sludge by electrochemical Fenton pretreatment

The electrochemical Fenton (electro-Fenton) pretreatment was explored as an attractive dewatering method for excess sludge produced in municipal wastewater treatment plants (MWTPs). The effects of initial pH, applied current density, zero valent iron (ZVI) dosage, and H2O2 concentration on sludge dewaterability and filterability were demonstrated by measuring water content (WC) and capillary suction time (CST) of conditioned sludge, respectively. Using radical scavenging tests, the significantly reduced WC and CST values in the electro-Fenton pretreatment compared to unconditioned sludge were attributed to both surface-bound OH and aqueous OH responsible for attacking and degrading extracellular polymeric substances (EPS). The component of tightly bound EPS (TB–EPS) was degraded to a greater extent as compared to soluble EPS (S–EPS) and loosely bound EPS (LB–EPS), resulting in the release of bound water to the aqueous phase. Protein and polysaccharide measurements in EPS fractions, together with FT–IR spectra, confirmed the preference of protein oxidation by OH. On the other hand, in the electro-Fenton process, ZVI was first electro-oxidized to Fe2+ for use in the Fenton reaction, then to Fe3+ that was subsequently reduced to Fe2+ under the applied electrical field, thereby leading to the cycle of iron (Fe2+ → Fe3+ → Fe2+). Moreover, ZVI/Fe3+ acted as scaffolds for agglomeration of flocs into large and compact particles for improved filterability. Results of this study could provide a basis to optimize the sludge dewatering process using the electro-Fenton pretreatment in MWTPs.

Reducing ultrafiltration membrane fouling during recycled paper mill wastewater treatment using pretreatment technologies: a comparison between coagulation and Fenton

AbstractBACKGROUNDUltrafiltration (UF) technology is efficient in treating wastewater. However, membrane fouling during filtration process affects the performance of UF to a large extent. Pretreatment prior to UF is important for enhancing membrane performance, reducing membrane fouling and extending the membrane lifetime.RESULTSIn this study, two pretreatment technologies, including coagulation and Fenton, were applied individually before UF for treating secondary effluent (SE) from recycled paper mill. Results exhibited that direct membrane filtration got the highest flux loss and worst membrane fouling compared with performances of those conducting pretreatments. Compared to coagulation + UF, Fenton + UF had superior performance in reducing dissolved organics with a COD rejection of 91.81%, and mitigating membrane fouling with a stable flux of 133 J m−2 h−1. GPC results further showed that Fenton pretreatment degraded macromolecules into smaller organic compounds. In addition, the classical blocking filtration laws were employed to scrutinize the fouling alleviation mechanism of pretreatments.CONCLUSIONPretreatments prolonged the transition from pore blocking to cake filtration, thereby reducing fouling. Among them, Fenton was a promising pretreatment method prior to UF for treating recycled paper SE. © 2018 Society of Chemical Industry

Efficient pretreatment of lignocellulosic biomass with high recovery of solid lignin and fermentable sugars using Fenton reaction in a mixed solvent

BackgroundPretreatment of biomass to maximize the recovery of fermentable sugars as well as to minimize the amount of enzyme inhibitors formed during the pretreatment is a challenge in biofuel process. We develop a modified Fenton pretreatment in a mixed solvent (water/DMSO) to combine the advantages of organosolv and Fenton pretreatments. The hemicellulose and cellulose in corncob were effectively degraded into xylose, glucose, and soluble glucose oligomers in a few hours. This saccharide solution, separated from the solid lignin simply by filtration, can be directly applied to the subsequent enzymatic hydrolysis and ethanol fermentation.ResultsAfter the pretreatment, 94% carbohydrates were recovered as soluble monosaccharide (xylose and glucose) and glucose oligomers in the filtrates, and 87% of solid lignin was recovered as the filter residue. The filtrates were directly applied to enzymatic hydrolysis, and 92% of raw corncob glucose was recovered. The hydrolysates containing the glucose and xylose from the enzymatic hydrolysis were directly applied to ethanol fermentation with ethanol yield equals 79% of theoretical yield. The pretreatment conditions (130 °C, 1.5 bar; 30 min to 4 h) are mild, and the pretreatment reagents (H2O2, FeCl3, and solvent) had low impact to environment. Using ferrimagnetic Fe3O4 resulted in similar pretreatment efficiency and Fe3O4 could be removed by filtration.ConclusionsA modified Fenton pretreatment of corncob in DMSO/water was developed. Up to 94% of the carbohydrate content of corncob was recovered as a saccharide solution simply by filtration. Such filtrate was directly applied to the subsequent enzymatic hydrolysis and where 92% of the corncob glucose content was obtained. The hydrolysate so obtained was directly applied to ethanol fermentation with good fermentability. The pretreatment method is simple, and the additives and solvents used have a low impact to the environment. This method provides the opportunity to substantially maximize the carbohydrate and solid lignin recovery of biomass with a comparatively green process, such that the efficiency of biorefinery as well as the bioethanol production process can be improved. The pretreatment is still relatively energy intensive and expensive, and further optimization of the process is required in large-scale operation.

Improvement of anaerobic digestion of sewage mixed sludge using free nitrous acid and Fenton pre-treatment

BackgroundRecently, it has been indicated that free nitrous acid (FNA) and Fenton pre-treatment of waste activated sludge can enhance methane production in anaerobic digestion of waste activated sludge. In addition, it has been revealed that the substances used in these pre-treatments are both eco-friendly and economically attractive because not only are they produced in anaerobic digestion, but they are also low priced. Since primary sludge and waste activated sludge are mixed prior to anaerobic digestion in the majority of wastewater treatment plants, this study aims to assess the influence of combined FNA and Fenton on the anaerobic digestion of mixed sludge.ResultsAccording to this study’s results, methane generation from anaerobic digestion of mixed sludge was enhanced when using FNA and Fenton pre-treatment, affirming the effectiveness of the individual and combined pre-treatments in anaerobic digestion of mixed sludge. The enhanced methane production was significant in combined pre-treatments (up to 72%), compared with FNA and Fenton pre-treatment alone (25% and 27%, respectively). This corroborates the positive synergistic effect of the combined pre-treatments on methane production. The enhanced methane can be attributed to augmented soluble fractions of organic matter in addition to increased readily biodegradable organic matter, caused by the pre-treatments. Additionally, the amount of chemical oxygen demand (COD) was assessed during anaerobic digestion, and it was revealed that COD decreased considerably when the pre-treatment strategies were combined.ConclusionsThis study reveals that the pre-treatments are potentially applicable to full-scale wastewater treatment plants because a mixture of primary sludge and waste activated sludge was used for the pre-treatments. Additionally, combined FNA and Fenton pre-treatments prove more effective in enhancing methane production and organic removal than these pre-treatments alone. The enhanced methane production is important for two reasons: a higher amount of renewable energy could be generated from the enhanced methane production and the COD of digested sludge reduces in such a way that facilitates application of the sludge to agricultural lands and reduces sludge transport costs.

Enhancing Effect of Residual Lignins from D. Sinicus Pretreated with Fenton Chemistry on Enzymatic Digestibility of Cellulose

AbstractTo screen and evaluate possible functional factors in the bamboo lignin moiety that could block non‐productive adsorption of enzyme proteins on lignin, milled wood lignin (MWL) and Fenton oxidized lignin (FOLs) were prepared and incorporated in the enzymatic hydrolysis of Avicel. The addition of MWL decreased the 72 h glucose yields of cellulose from 57.1 % to 45.3 %, while FOLs effectively improved the enzymatic digestibility up to 69.5 %, which was 22 % higher than the system without the use of FOLs. The adsorption affinity and binding strength of cellulase with FOLs were lower than that with MWL. After Fenton pretreatment, hydrophilicity of lignins increased due to formation of C−O− and O−C=O bonds. Furthermore, high surface negative charges on FOLs resulted in strong electrostatic repulsion against the negatively charged cellulases. Finally, analysis of FOLs with 13C and 2D‐HSQC NMR indicated that the cleavage of β‐O‐4 linkages and demethoxylation occurred, and that less condensed structures at the Cβ and Cγ positions were observed. These oxidation reactions of the bamboo lignin lead to the formation of functional factors to alleviate irreversible adsorption of cellulase onto FOLs, and thus were responsible for promoting enzymatic digestibility efficiency.

A bionic system with Fenton reaction and bacteria as a model for bioprocessing lignocellulosic biomass

BackgroundThe recalcitrance of lignocellulosic biomass offers a series of challenges for biochemical processing into biofuels and bio-products. For the first time, we address these challenges with a biomimetic system via a mild yet rapid Fenton reaction and lignocellulose-degrading bacterial strain Cupriavidus basilensis B-8 (here after B-8) to pretreat the rice straw (RS) by mimicking the natural fungal invasion process. Here, we also elaborated the mechanism through conducting a systematic study of physicochemical changes before and after pretreatment.ResultsAfter synergistic Fenton and B-8 pretreatment, the reducing sugar yield was increased by 15.6–56.6% over Fenton pretreatment alone and 2.7–5.2 times over untreated RS (98 mg g−1). Morphological analysis revealed that pretreatment changed the surface morphology of the RS, and the increase in roughness and hydrophilic sites enhanced lignocellulose bioavailability. Chemical components analyses showed that B-8 removed part of the lignin and hemicellulose which caused the cellulose content to increase. In addition, the important chemical modifications also occurred in lignin, 2D NMR analysis of the lignin in residues indicated that the Fenton pretreatment caused partial depolymerization of lignin mainly by cleaving the β-O-4 linkages and by demethoxylation to remove the syringyl (S) and guaiacyl (G) units. B-8 could depolymerize amount of the G units by cleaving the β-5 linkages that interconnect the lignin subunits.ConclusionsA biomimetic system with a biochemical Fenton reaction and lignocellulose-degrading bacteria was confirmed to be able for the pretreatment of RS to enhance enzymatic hydrolysis under mild conditions. The high digestibility was attributed to the destruction of the lignin structure, partial hydrolysis of the hemicellulose and partial surface oxidation of the cellulose. The mechanism of synergistic Fenton and B-8 pretreatment was also explored to understand the change in the RS and the bacterial effects on enzymatic hydrolysis. Furthermore, this biomimetic system offers new insights into the pretreatment of lignocellulosic biomass.

Application of Fenton pretreatment on the degradation of rice straw by mixed culture of Phanerochaete chrysosporium and Aspergillus niger

The rice straw (RS) is a kind of recalcitrant lignocellulosic material. The Fenton reaction has been widely used for the degradation of organic compounds and toxic chemicals. Therefore, applying it to pretreatment straw seems to have good potential. This study was to investigate the degradation of the pretreated RS by the mixed solid-state culture with Phanerochaete chrysosporium and Aspergillus nigert. The results showed that the degree of delignifition was 15.01% by using an optimized Fenton reagent (6 g/L of FeSO4·7H2O and 15% concentration of H2O2) at a solids loading of 5% (w/v) and a moderate temperature for 15 h. The analysis of the Fenton pretreated RS by Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) showed significant changes in physicochemical structure, favoring the subsequently susceptibility of ligninolytic enzymes. The volatile organic compounds collected from the mixed solid-state culture implied the degradation degree of the lignocellulose to some extent. In conclusion, Fenton pretreatment could effectively disrupt the recalcitrant structure of RS and accelerate its biodegradation, which has high potential application in the energy conversion and utilization of lignocellulose.

The Effect of Advanced Oxidation Pre-Treatment on the Membrane Filtration Parameters of Dairy Wastewater

Abstract The dairy industry generates wastewater characterised by high levels of biological and chemical oxygen demands representative of their high degree of organic content; mainly carbohydrates, proteins and fats that originate from milk. Several investigations have been conducted into the reuse of dairy wastewater, e.g. membrane processes are a promising method to treat such wastewater. Earlier works have proven that with membrane filtration an appropriate degree of retention can be achieved and the permeate can be reused. However, membrane fouling is a limiting factor in these processes. Advanced oxidation processes (AOPs) are widely used in the fields of water and wastewater treatments and are known for their capability to mineralise a wide range of organic compounds. AOPs also exhibit some other effects on the filtration process, e.g. the microflocculation effect of ozone may play a significant role in increasing the elimination efficiency and causing a decreased level of irreversible fouling. By comparing ozone and Fenton pre-treatment (FPT) processes it can be shown that the fouling propensity of pre-treated pollutants does not depend on the pre-treatment method, while FPT was proven to be more efficient in improving the level of flux.

Electrochemical nitrate reduction by using a novel Co3O4/Ti cathode

Co3O4 film coated on Ti substrate is prepared using sol-gel method and applied as cathode material for electrochemical denitrification in this research. Preparation conditions including precursor coating times and calcination temperature are optimized based on NO3−-N removal, NO2−-N generation, NH4+-N generation and total nitrogen (TN) removal efficiencies. The influences of electrolysis parameters such as current density and NO3−-N initial concentration are also investigated. In comparison with other common researched cathodes (Ti, Cu and Fe2O3/Ti), Co3O4/Ti exhibits better NO3−-N removal and NH4+-N generation efficiencies. In order to remove NO3−-N completely from water, Cl− is added to help further oxidize NH4+-N to N2. TN removal after 3 h treatment increases from 65% to 80%, 90% and 96% with the increase of Cl− from 0 mg L−1 to 500, 1000 and 1500 mg L−1, respectively. The mechanisms of NO3−-N reduction on cathode and NH4+-N oxidation on anode in the absence and presence of Cl− are investigated in a double-cell reactor. Actual textile wastewater containing both NO3− and Cl− is also treated and the Co3O4/Ti cathode exhibits excellent stability and reliability. It is interesting to find out that FeCl2-H2O2 Fenton pretreatment is needed to remove extra COD and provide more Cl− to help oxidize NH4+-N to N2 at the same time.

Effect of Fenton pretreatment on anaerobic digestion of olive mill wastewater and olive mill solid waste in mesophilic conditions

ABSTRACTThe olive mill waste (OMW) generated from olive oil extraction process constitutes a major environmental concern owing to its high organic and mineral matters and acidic pH. Anaerobic digestion (AD) is a main treatment for reducing the organic matter and toxic substances contained in OMW and generating at the same time, energy in the form of biogas. AD of OMW that contains lignocellulose is limited by the rate of hydrolysis due to their recalcitrant structure. This study is devoted to the effect of Fenton process (FP) pretreatment on olive mill wastewater (OMSW) /olive mill solid waste (OMWW) co-digestion to improve their digestibility and in this way the biogas production. The FP pretreatment was performed in batch mode at 25°C, various H2O2/[Fe2+] ratios (100–1200), catalyst concentration ([Fe2+]) ranging from 0.25 to 2 mM, reaction time varying from 30 to150 min, and different pH (3–11). The best performance was obtained with H2O2/[Fe2+] = 1000, [Fe2+] = 1.5 mM, 120 min, and pH 3. Biochemical methane potential (BMP) tests conducted in batch wise digester and at mesophilic conditions (37 °C) showed that cumulative biogas and methane production were higher without FP treatment, and correspond to 699 and 416 mL/g VS, respectively. However, pre-treated OMSW results into an increase of 24% of methane yield. After 30 days of AD, the methane yield was 63%, 54%, and 48%, respectively, for OMSW treated without iron precipitation, with iron precipitation and untreated OMSW sample.

Fenton pre-treatment of rice straw with citric acid as an iron chelate reagent for enhancing saccharification

Rice straw was pre-treated by Fenton action with citric acid for chelation; the pre-treated rice straw was saccharified byRuminiclostridium thermocellumM3.

Evaluation and optimization of Fenton pretreatment integrated with granulated activated carbon (GAC) filtration for carbamazepine removal from complex wastewater of pharmaceutical industry

The bulk manufacturing of carbamazepine (CBZ) by pharmaceutical manufacturing industries leads to generation of huge amount of wastewater containing this recalcitrant compound. This necessitates the application of advanced oxidation processes (AOPs) as a pretreatment strategy for the treatment of such complex industrial wastewaters. Therefore, in the present study, effect of Fenton treatment was investigated for removal of CBZ from real wastewater containing higher CBZ concentrations. The preliminary studies were conducted to assess the significant factors in Fenton treatment and pH, Fenton dose and time were found to be statistically significant parameters affecting the Fenton process. Based on these results, further experimental trials were designed statistically using Central Composite Design in MINITAB 16 software. The process conditions were optimized using Response Surface Optimizer Tool in MINITAB 16 and pH=3.5 and H2O2 concentration of 8.5g/L was obtained as optimum condition leading to 49.39±0.93% CBZ removal from pharmaceutical wastewater containing higher CBZ concentrations. The detoxification of Fenton-treated wastewater through granulated activated carbon (GAC) column resulted in an overall CBZ removal of 99.51±0.02%. The detoxification was further corroborated through seed germination test which demonstrated a potential reduction in toxicity post-detoxification using GACs.

Improved treatment approach for the removal of aromatic compounds using polymeric beads in Fenton pretreatment and biological oxidation.

An improved approach based on the use of iron-doped polymeric beads (IPB) as Fenton catalyst in the pretreatment and biomass-doped polymeric bead (BPB) in the biological oxidation has been reported for the removal of different aromatic mixtures present as pollutants in the aqueous solutions. Degradation has been investigated at fixed loading of IPB as 2.5% weight basis and varying loading of hydrogen peroxide so as to understand the effect of oxidant loading on the extent of degradation. It has been observed that the maximum removal efficiency as 75.5, 81.4, and 59.1% was obtained for the benzene-toluene-naphthalene-xylene (BTNX), benzene-toluene-ethylbenzene-xylene (BTEX), and benzene-toluene-naphthalene-p-nitrophenol (BTNp-NP) mixtures, respectively, at a 40-min pretreatment and optimum pH of 3.5. The biodegradability index was also observed in the favorable range of 0.4 to 0.5 after the pretreatment at optimum H2O2 loading of 1.5gL-1. Maximum COD removal efficiency of 99.2, 99.3, and 99.6% was obtained using the biological oxidation treatment for 40h for the case of BTNX, BTEX, and BTNp-NP mixtures, respectively. Analysis of kinetic models revealed that degradation followed three distinct stages based on fitting of the three-stage model and BPB was found to be more efficient as compared to the primary activated sludge (PAS) and modified activated sludge (MAS). Reusability studies confirmed that both IPB and BPB were effective over many cycles giving stable performance during degradation without leaching of Fe3+ ions into the solution.

Enhanced Enzymatic Hydrolysis of Poplar after Combined Dilute NaOH and Fenton Pretreatment

Five types of pretreatment processes were investigated to confirm the enhancement of the enzymatic hydrolysis of poplar. These processes included a hot water pretreatment, a calcium oxide pretreatment, NaOH extraction at low temperature, a Fenton reaction, and a combined dilute NaOH and Fenton pretreatment. The combined dilute NaOH and Fenton pretreatment was found to be the most effective pretreatment process. After enzymatic hydrolysis for 72 h, 74% of the cellulose recovery yield was obtained when the poplar substrates were pretreated with 2% NaOH at 75 °C for 3 h, followed by 20 mmol/g of H2O2 (30%) and 0.2 mmol/g of FeSO4·7H2O for a Fenton reaction period of 12 h. The cellulose recovery yield was approximately five-fold greater than that of the untreated sample directly processed by enzymatic hydrolysis. Furthermore, microscopic observations of changes in the surface structure of the pretreated residue were correlated with the enhancement of the enzymatic hydrolysis of cellulose. In conclusion, the combined dilute NaOH and Fenton pretreatment shows high potential for future application.

A comparative study of enzymatic and Fenton pretreatment applied to a birch kraft pulp used for MFC production in a pilot scale high-pressure homogenizer

Microfibrillated cellulose (MFC) was produced in pilot scale from a bleached birch (Betula verrucosa) kraft pulp that was pretreated with either Fenton’s reagent or with a combined mechanical and enzymatic method used at the Centre Technique du Papier (CTP; Grenoble, France). The change in fiber fibrillation during the homogenization treatment was monitored by analyzing the fiber and the fines content, size fractionation, rheological properties and visualization by light- and scanning electron microscopy (SEM). The Fenton pretreatment resulted in MFC suspensions that contained a high amount of small sized elements. After five passes through the highpressure homogenizer, the amount of particles smaller than 20 μm was 37% for the Fenton pretreated MFC compared to 13% for the enzymatically (endoglucanase) pretreated MFC. Altogether, the Fenton pretreatment enabled preparation of MFC with a higher degree of fibrillation after the same number of passes through the high-pressure homogenizer. Another option is to produce MFC of the same amount of fibrillation as after an enzymatic stage, but at significantly lower energy consumption.

Enhancement of activated sludge disintegration and dewaterability by Fenton process

Municipal and industrial wastewater treatment plants produce large amounts of sludge. This excess sludge is an inevitable drawback inherent to the activated sludge process. In this study, the waste activated sludge was obtained from the campus wastewater treatment plant at Universiti Teknologi PETRONAS (UTP), Malaysia. Fenton pretreatment was optimized by using the response surface methodology (RSM) to study the effects of three operating conditions including the dosage of H2O2 (g H2O2/kg TS), the molar ratio of H2O2/Fe2+ and reaction time. The optimum operating variables to achieve MLVSS removal 65%, CST reduction 28%, sCOD 11000 mg/L and EPS 500 mg/L were: 1000 g H2O2/kg TS, H2O2/Fe2+ molar ratio 70 and reaction time 45 min. Fenton process was proved to be able to enhance the sludge disintegration and dewaterability.

Enhancing enzymolysis and fermentation efficiency of sugarcane bagasse by synergistic pretreatment of Fenton reaction and sodium hydroxide extraction

A study on the synergistic pretreatment of sugarcane bagasse (SCB) using Fenton reaction and NaOH extraction was conducted. The optimized process conditions for Fenton pretreatment were 10% (w/w) of H2O2, 20mM of Fe2+, pH 2.5, pretreatment time 6h, and pretreatment temperature 55°C. Sequential pretreatments were performed in combination with NaOH extraction (NaOH 1% (w/w), 80°C, 5% of solid loading, 1h). Among all the pretreatments, Fenton pretreatment followed by NaOH extraction had the highest efficiency of 64.7% and 108.3% for enzymolysis and simultaneous saccharification fermentation (SSF) with an ethanol concentration of 17.44g/L. The analyses by the scanning electron microscopy, X-ray diffraction and confocal laser scanning microscopy revealed that Fenton pretreatment disrupts the structure of SCB to facilitate the degradation of lignin by NaOH. The overall data suggest that this combinatorial strategy is a promising process for SCB pretreatment.

Performance of passive aerated immobilized biomass reactor coupled with Fenton process for treatment of landfill leachate

The passive aerated immobilized biomass (PAB) reactor was investigated for the treatment of landfill leachate. Reactor performance was affected by hydraulic retention time (HRT), organic loading rate (OLR), volatile suspended solids to total suspended solids ratio (VSS/TSS) and CODtotal/NH4-N ratio. CODtotal and NH4-N removal efficiency dropped from 55 ± 6 to 33 ± 2% and from 93 ± 8 to 80 ± 11%, when the HRT was decreased from 16 to 4 h, respectively. Ammonia oxidation increased from 69 to 94% at decreasing the VSS/TSS ratio from 0.54 to 0.24, respectively. Fenton pre-treatment substantially improved the removal efficiency of CODtotal (83 ± 4%) and CODsoluble (83 ± 5%). The simple empirical model designed to assess the performance of PAB reactor treating landfill leachate showed good agreement between predicted and experimental parameter values.