Chemical Oxygen Demand Degradation Research Articles

Electronic structure regulation of Cu-based Ruddlesden-Popper perovskites by cobalt doping for enhanced degradation of oilfield fracturing wastewater in electrocatalytic peroxymonosulfate system

Purification of oilfield fracturing wastewater is the most challenging type of oilfield wastewater treatment. In this work, a heterogeneous electrocatalytic peroxymonosulfate (PMS) system was established to treat oilfield wastewater using Co-doping induced Cu-based Ruddlesden-Popper (RP) perovskites as catalysts. Characterization results illustrated that the obtained catalysts were generated the heterojunction of LaCoO3/La2CuO4 and the Co would transfer electrons to Cu, resulting in a higher chemical oxygen demand (COD) degradation efficiency (> 80 %) of oilfield fracturing wastewater under the neutral environment. Singlet oxygen (1O2) played the main function for COD removal with analysis results of reactive oxygen species (ROS). Experimental results and theoretical calculations indicated that the reduction effect of carbon felt (GF) cathode and the redox cycle of Cu(I)/Cu(II) and Co(II)/Co(III) accelerated the activation of PMS. Moreover, the lattice oxygen participated in the generation of ROS. Significantly, the LaCoO3/La2CuO4 heterojunction displayed a higher total density of states (TDOS) value near the Fermi level, implying their favorable electron transfer for PMS activation. This study opens new avenue for resolving the challenge of oilfield fracturing wastewater pollution.

Toxicological assessment of reactive blue 19 dye aqueous solutions under UV-LED light

Abstract The dye-contaminated industrial effluent causes serious health issues when it gets mixed with underground water without primary treatment. The current project was designed to treat reactive blue-19 dye aqueous solutions in the presence of hydrogen peroxide (H2O2) and titanium dioxide (TiO2) under UV-LED light. The characterization of the photocatalyst was carried out via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) for structure, purity, and surface study. The effect of various factors such as pH, TiO2 dose, UV-LED light exposure time, H2O2, and dye concentration, on the degradation rate and cytotoxicity reduction was evaluated and optimized through the Response Surface Methodology (RSM). The maximum degradation of dye solution and chemical oxygen demand (COD) reduction was achieved at 98.81 and 86.22 %, respectively for 50 ppm solution, using UV-LED/H2O2(3 %)/TiO2(6 g/L) hybrid process. The toxicity evaluation through the Allium cepa test demonstrated a 62.40, 65.2, and 56.97 % increase in root length (RL), root count (RC), and mitotic index (MI), respectively, following treatment with the UV-LED/H₂O₂/TiO₂ combined process for 150 min. The hemolytic and brine shrimp tests revealed a reduction in toxicity up to 92.18 and 84.08 %, respectively, after applying the same treatment. Additionally, the Ames test indicated up to 80.94 % reduction in mutagenicity for TA98 and an 84.04 % reduction for TA100 strain when dye samples were treated with UV-LED light in the presence of H₂O₂ and TiO₂ for 150 min. The findings suggested that UV-LED light in conjunction with H2O2 and TiO2 can be a useful tool for the degradation and detoxification of toxic pollutants found in textile wastewater.

Domestic wastewater treatment towards reuse by “self-supplied” microbial electrochemical system assisted UV/H2O2 process

Domestic wastewater is a potential source of water for non-potable reuse that may help address the global water, energy, and resource challenges. Herein, a “self-supplied” process through integrating microbial electrochemical system (MES) with UV/H2O2 was developed and investigated for wastewater treatment. H2O2 was “self-supplied” from MES while the MES catholyte was “self-supplied” from the final effluent of UV/H2O2. It was found that the MES accomplished > 80 % degradation of chemical oxygen demand (COD) through bioanode degradation, and produced 18 - 20 mg L−1 H2O2 via oxygen reduction reaction in the gas diffusion cathode. The MES effluent was further treated by the UV/H2O2 process, which achieved the complete removal of recalcitrant diclofenac and > 6 log inactivation of Escherichia coli. The enhanced treatment performance of UV/H2O2 was demonstrated via a comparison with the control experiments (UV or H2O2 treatment) and benefited from ·OH generation and sulfide removal. When treating the actual wastewater, the proposed system exhibited consistent treatment performance for the organic compounds and recalcitrant contaminants, and the quality of the treated water would meet the non-potable water reuse guidelines. The results of this study encourage the further exploration of emerging contaminant removal, system coordination, and use of renewable energy by the cooperation between MES and UV/H2O2.

Chemical structure dependent electrochemical degradation of antibiotics using Boron-doped Diamond Electrodes

The electrochemical degradation of Amoxicillin (AMOX), Ciprofloxacin (CIP), and Streptomycin (STR) utilizing Boron-Doped Diamond Electrodes (BDD) was explored under varying levels of applied electrical current density and initial buffer acidity. These pharmaceuticals were carefully selected to showcase the efficiency of electrochemical oxidation across different major chemical structure antibiotic families. The results demonstrated a positive correlation between higher applied current density and the elimination of antibiotics, as well as enhanced chemical oxygen demand (COD) removal rate. However, a negative impact was observed on the specific energy consumption (SEC). Notably, the highest antibiotics and COD removal efficiencies, along with the lowest SEC, were achieved at an applied current density of 45 mA/cm2. Furthermore, the investigation highlighted the significant influence of the chemical structure of the selected antibiotics on their degradation process. At a current density of 15 mA/cm2 and after 24 minutes of treatment, the degradation order was found to be AMOX > CIP > STR, with respective antibiotic removal efficiencies of 98.5 %, 87.8 %, and 81.1 %. Similarly, after 90 minutes of treatment, the COD degradation efficiency followed the order AMOX (50.4 %) > CIP (47.3 %) > STR (44.6 %), accompanied by decreasing levels of specific energy consumption, measuring 59, 61, and 67 kWh/kg COD, respectively, with an average current efficiency of 23–26 %. The pH had a significant effect on the streptomycin degradation rate, while it had a negligible impact on the degradation rate of ciprofloxacin. These findings shed light on the critical role of the pharmaceuticals' chemical structures and environmental conditions in governing the efficiency of their electrochemical degradation.

Comparative study on the effects of anionic, cationic, and nonionic polyacrylamide surface modified magnetic micro-particles (MMP) for anaerobic digestion treatment of vegetable waste water (VWW)

Anaerobic digestion provides a solution for the treatment of vegetable waste water (VWW), but there are currently limited targeted treatment methods available. Building upon previous studies, this research investigated the effects of polyacrylamide-modified magnetic micro-particles (MMP) on anaerobic digestion (AD) of VWW. Three variations of these particles were created by grafting anionic, cationic, and non-ionic polyacrylamide (PAM) onto the MMPs’ surfaces, resulting in aPAM-MMP, cPAM-MMP, and nPAM-MMP, respectively. In AD experiments, the addition of aPAM-MMP notably enhanced the degradation of chemical oxygen demand (COD) in VWW. COD decreased to 1290 mg/L in the reactor with aPAM-MMP by day 12 and remained low, while the other reactors had COD concentrations of 4137.5, 5510, and 3010 mg/L on the same day, decreasing thereafter. This modification also improved the production and utilization of hydrogen gas and volatile fatty acids (VFAs), along with the conversion of methane. When tested for bioaffinity using fluorescent GFP-E.coli bacteria, the aPAM-MMP, cPAM-MMP, and nPAM-MMP demonstrated increases in fluorescence intensity by 51.66%, 36.13%, and 37.02%, respectively, compared to unmodified MMP when attached with GFP-E.coli. Further analyses of microbial community revealed that the reactor with aPAM-MMP had the highest microbial richness and enriched bacteria capable of organic matter degradation, such as Bacteroidota, Synergistota, Chloroflexi, Halobacterota phyla, and Parabacteroides, Muribaculaceae, and Azotobacter genera. In conclusion, our experiment verifies that APAM-MMP promotes anaerobic treatment of VWW and provides a novel reference point for enhancing VWW degradation.

Biochar accelerates methane production efficiency from Baijiu wastewater: Some viewpoints considering direct interspecies electron transfer

The low pH of Maotai-flavor Baijiu wastewater (MFBW) adversely affects its anaerobic digestion (AD) performance, resulting in low AD efficiency. Here, coconut shell was used to produce biochar. The characteristics of biochar were regulated through acid, alkali, and magnetic modification, respectively. Biochar and modified biochars were applied to assist the AD of MFBW. The results showed that biochar could significantly increase methane yield by 220.8 %–241.7 % with the corresponding soluble chemical oxygen demand (sCOD) degradation increasing by 52.3 %–57.5 % (p < 0.05). Joint modification could significantly enhance the electron donating capacity from 0.0042 to 0.0095 mmol e−1/g (p < 0.05). The combined modification with magnetic alkali had the best stimulating effect on the AD process, which might be related to the conductive particles (Fe3O4) formed during magnetization processes. The modified biochar featured a high degree of surface roughness, a relatively large aperture, and strong electron donating ability, all of which were beneficial to the colonization and microbial growth. Supplementation with biochar resulted in the enrichment of Proteobacteria, Firmicutes, and Actinobacteria, especially for Syntrophomonas (rising from 0.013 % to 6.74 %–10.93 % of relative abundance). These microorganisms are related to the hydrolysis, acidification, and extracellular electron transfer. The enrichment of electroactive microorganism is a prerequisite for improving the direct interspecies electron transfer pathway. This study provides theoretical support for efficient MFBW treatment.

Manufacturing of Fe/C micro-electrolysis materials with the pyrite cinder towards the degradation of high-concentration organic wastewater

Large volumes of pyrite cinder (PyC) was produced about 12 million tons/a in China but the utilization rate is low. In this work, an innovate method has been developed to utilize the hazardous pyrite cinder for manufacturing Fe/C micro-electrolysis materials, which can be used to degrade high-concentration organic wastewater. The effects of preparation conditions on degradation performance of materials were investigated based on the removal rate of chemical oxygen demand (COD) from the simulated methylene blue wastewater containing 500 mg/L initial COD. The results demonstrated that the impressive COD degradation of ICMEM reached 94.37 % within 120 min under manufacturing at 950℃ for 75 min via carbothermal reduction of PyC pellets with 15 % carbon addition. The X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and chemical phase were used to reveal that the formation of Fe0 and Cu0 resulted in the creation of numerous galvanic cells with carbon and effectively facilitating the degradation of methylene blue. This research presents an innovative approach towards cost-effective PyC recycling and he degradation of methylene blue in wastewater.

Removal of metronidazole using a novel ZnO–CoFe2O4@Biochar heterostructure composite in an intimately coupled photocatalysis and biodegradation system under visible light

The intimate coupling of photocatalysis and biodegradation (ICPB) technology has received much attraction because of the advantages of both photocatalytic reaction and biological treatment. In this study, ZnO–CoFe2O4@BC (ZCFC) with p-n heterojunction was prepared and used in an ICPB system to degrade metronidazole (MNZ) wastewater. The microstructure, morphology, and optical behavior of heterojunctions in ZCFC were investigated using SEM, XRD, UV–vis, FTIR, and XPS techniques. The results showed that ZCFC inherited the advantages of bamboo biochar's large pore size, and its large pore structure could provide a habitat for bacterial colonization in ICPB, thus shortening the internal mass transfer distance. The degradation of MNZ and chemical oxygen demand (COD) by the ICPB system was 86.8% and 58.5%, respectively, which was superior to single photocatalysis (72.5% for MNZ and 43.8% for COD) and single biodegradation (23.5% for MNZ and 20.1% for COD). In ICPB, photocatalysis and biodegradation showed a synergistic effect in the removal of MNZ, and the order of the major reactive oxygen species (ROS) leading to reduced toxicity of MNZ to the biofilm was •OH > h+ > O2•-. High-throughput sequencing analysis showed continuous evolution of biofilm structures in ICPB enriched a variety of functional species, among which the electroactive bacteria Alcaligenes and Brevundimonas played an important role in the degradation of MNZ. In this study, we investigated the possible mechanism of photocatalytic and microbial synergistic degradation of MNZ in the ICPB system and proposed a new technology for degrading antibiotic wastewater that combines the advantages of photocatalysis and biodegradation.

Degradation of chemical oxygen demand, suspended solids and ammoniacal nitrogen from sewage by sweet potato peel coagulant under the influence of pH

Degradation of chemical oxygen demand, suspended solids and ammoniacal nitrogen from sewage by sweet potato peel coagulant under the influence of pH

Application of immobilized biological fillers for the hydrolytic acidification and denitrification of sulfide-containing tannery wastewater

This study investigated the application of immobilized biological fillers in the hydrolytic acidification (HA) and denitrification (DN) of actual sulfide-containing tannery wastewater (TWW) through pilot-scale systematic experiments, which provided technical insights for the engineering application of immobilized bio-filler in practical TWW treatment. HA fillers and DN fillers could effectively realize the enrichment and maintenance of functional flora even under long-term inhibition of high sulfide concentration. The HA fillers demonstrated efficient conversion of organic nitrogen. At a hydraulic retention time (HRT) in the range of 3–6 h, the HA reactor achieved an average organic nitrogen conversion concentration of about 100 mg/L, accounting for 56.2 %-68.5 % of the total organic nitrogen in the TWW. Under this condition, the highest average organic nitrogen conversion and mean chemical oxygen demand (COD) degradation efficiencies were achieved, at 32.95 mgNH4+-N/(L·h) and 179.42 mgCOD/(L·h), respectively. Free ammonia (FA) may contribute to pH stabilization in the HA reactor. Denitrification fillers could utilize the endogenous organic matter in the actual TWW hydrolyzed acidified solution, and realize stable biological nitrogen removal effect with no additional carbon source. The denitrification rate reached 76.3 mg NO3--N/(L·h) and the ΔC/ΔN of the denitrification ranged from 3 to 4.

Electrochemical preparation and characterization of a new configuration SnO2 anode and its application for treating petroleum refinery wastewater

In the present work, the feasibility of removing chemical oxygen demand (COD) from petroleum refiner wastewater (PRW) was examined through an anodic oxidation process using a SnO2-copper substrate anode in a prototype tubular batch electrochemical reactor. The SnO2 anode was prepared by cathodic deposition from a nitrate solution and characterized by techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). Effects of current density, [Sn2+]/[HNO3] molar ratio, and time on the properties of the prepared anode were investigated. The XRD results showed that main peaks corresponded to deposition of tetragonal SnO2. Besides, broad peeks were observed indicating that the deposits have a lower degree of crystallinity. The results confirmed that increasing current density higher than 10 mA/cm2 results in formation of a mixture of SnO2 and Sn deposits. Additionally, the results proved that [Sn2+]/[HNO3] molar ratio has the main effect on the electrodeposition process, where keeping this ratio lower than 0.33 is recommended to ensure pure SnO2 film deposition. The best conditions for electrodeposition of SnO2 as a compact film on a copper substrate were a current density of 10 mA/cm2, [Sn2+] of 25 mM, [HNO3] of 125 mM to make a molar ratio of 0.2, and 30 min to confirm the formation of deposits without cracks and having an atomic percent (Sn/O) of 20.6/65. The application of the prepared anode for removing of COD from PRW confirmed a good performance with a removal efficiency of 79 % at current density of 12 mA/cm2, pH of 7.8, and operating time of 150 min in which an energy consumption of 9.93 kWh/kg COD was required. The degradation of COD using the SnO2 electrode was found to obey a pseudo first-order kinetic. The application of anodic oxidation using the new configuration of the SnO2 anode can be considered an eco-friendly process for treating wastewater, featuring easy scale-up to an industrial scale at high removal efficiency and lower cost.

Low voltage electric field mediating gravity-driven membrane bioreactor in treating saline wastewater: removal improvement and membrane fouling control

Gravity-driven membrane bioreactor (GDMBR) endowed with low maintenance and energy consumption owing to its combinations between biological degradation and membrane rejection, however, has not been reported in treating the saline wastewater due to the potential biological inhibition. This study investigated the effects of salt on GDMBR performance, and introduced a novel low voltage electric field (eGDMBR) with hopes to mediate the biological activity and improve the filtration performance. The influence of different low voltage electric fields (0.25 V, 0.50 V, and 0.75 V) on the flux variations and contaminants removal of eGDMBR were investigated. The results demonstrated that integrating low voltage electric field into GDMBR would not impact the appearance of flux stabilization, but delivered a significant influence on its stabilized flux level, and 0.50 V was the optimized voltage, contributing to a substantial flux improvement of 47.10 % in eGDMBR-0.50. Moreover, with the assistance of low voltage electric fields, eGDMBR process obtained an effective removal of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N) and total phosphorus (TP), accounting for average removal efficiency of 54.01 %, 73.08 % and 25.74 %, respectively. Compared to the control, coupling 0.50 V voltage electric field to GDMBR was beneficial to engineer a loose, porous and heterogeneous structure of membrane biofilm and also reduce the accumulation of extracellular polymeric substance (EPS), significantly contributing to alleviating the membrane fouling. Furthermore, with the assistance of low voltage electric fields, the Proteobacteria was enriched by a relative abundance of 58.58 % in the membrane biofilm of eGDMBR-0.50, which was in favor of the degradation of COD and NH4+-N. Therefore, these findings indicated that eGDMBR conferred significant superiorities in treating the saline wastewater and mitigating membrane fouling.

Is water replenishment an effective way to improve lake water quality? Case study in Lake Ulansuhai, China

Lakes are an important component of the global water cycle and aquatic ecosystem. Lake water quality improvement have always been a hot topic of concern both domestically and internationally. Noncompliant outflow water quality frequently occurs, especially for lakes that rely mainly on irrigation return flow as their water source. External water replenishment to improve the water quality of lakes is gradually being recognized as a promising method, which however, is also a controversial method. Lake managers, in the case of constant controversy, hesitate about the appropriateness of lake water replenishing. Thus, taking Lake Ulansuhai in China as an example, this study aimed to construct a lake hydrodynamic and water quality model, under the constraint of multiple boundary conditions, that has sufficient simulation accuracy, and to simulate and analyze the changes in COD (Chemical Oxygen Demand) and TN (Total Nitrogen) concentrations in the lake area before and after water replenishment, and explore whether water replenishment was an effective method for improving lake water quality. The results showed that when the roughness value of Lake Ulansuhai was 0.02, the TN degradation coefficient K was 0.005/d, and the COD degradation coefficient K was 0.01/d; the simulation and measured values had the best fit, and the built model is reasonable and reliable can be used to simulate lake water quality changes. By external water replenishment lasting 140 days in the water volume of 4.925 × 108 m³, the COD and TN concentrations in Lake Ulansuhai could be stabilized at the Class V water quality requirement, which helped improve the self-purification ability of the lake area. Water replenishment was proved to be an effective method for improving the water quality of the lake, but water replenishment is only an emergency measure. Lake water replenishment is more applicable to areas with abundant water resources. External source control and internal source reduction of lake pollution and protection of lake water ecology are the main ways to improve lake water quality for water-deficient areas under the rigid constraints of water resources. In the future, key technologies for reducing and controlling pollution in irrigation areas, construction of lake digital twin platforms, and active promotion of lake legislation work should be the main research direction for managing the lake water environment.

Bench-scale supercritical and near-supercritical water oxidation assays to treat Propylene Oxide-Styrene Monomer (POSM) wastewater

Supercritical Water Oxidation is a promising technology to deal with the phenolic-benzoic nature of the wastewater from Propylene Oxide-Styrene Monomer processes. To assess its feasibility to meet discharge regulations for a continuous process, lab-scale assays were conducted with real wastewater. After a screening to maximize Chemical Oxygen Demand (COD) removal efficiency, a supercritical, four-hour duration test was run at 550 °C, 235 bar g, with 50% excess oxygen and residence time of 120 seconds. Though a successful COD degradation of 99.97 ± 0.01% was achieved, salt scaling and corrosion occurred. The key findings are that to redissolve salts and avoid corrosion, focus must be on the supercritical to subcritical transition location. Near-supercritical oxidation was also tested as a cost-effective alternative to avoid scaling. Residence times up to 192 min were required at 300 °C, 165 bar g and 40% excess oxygen to achieve similar degradation obtained to supercritical conditions.

Three-dimensional electro-Fenton system with steel-slag based particle electrode for the treatment of refinery spent caustic

Refinery spent caustic (RSC) is a highly contaminated wastewater originated from the petroleum refining industry with complicated chemistry and high toxicity. In this work, a novel three-dimensional electro-Fenton (3DEF) system assisted by electromagnetic induction was developed to treat an actual RSC with a chemical oxygen demand (COD) concentration of 27000–33000 mg/L. Industrial waste steel slag was used as both the particle electrode and the Fenton’s catalyst. Under optimal conditions, COD removal reached 93.6% within 90 min. Electromagnetic induction significantly enhanced COD degradation by promoting the corrosion of steel slag, inhibiting the electrode passivation, and enhancing the thermal activation of hydrogen peroxide. The reusability of steel slag was also enhanced by electromagnetic induction. Radical quenching tests demonstrate that hydroxyl radicals (•OH) played a main role in the pollutant degradation. The system is of good economic and environmental benefits with a total treatment cost of about 1.015 $/m3, achieving the objective of “treating waste with waste”.

A cathodic electro-fermentation system for enhanced methane production from high-concentration potato starch industrial wastewater

The high chemical oxygen demand (COD) concentration of potato starch industrial wastewater makes it very challenging for traditional anaerobic digestion (AD) to treat. Here we proposed to use the cathodic electro-fermentation system to enhance the methane production from potato starch industrial wastewater (7546 mg·L−1 COD). Compared with the traditional AD, the electro-fermentation system enhanced the maximum methane production rate more than three times and increased the cumulative methane production by 30 %. What's more, the lag phase of the AD was dramatically reduced, and the COD degradation rate was significantly improved in the electro-fermentation system. The better performance could be attributed to the fact the electro-fermentation system could avoid the accumulation of the intermediate metabolites (e.g. volatile fatty acids (VFAs)) and maintain a suitable pH for methanogens. Additionally, the applied potential at the cathode enhanced the acidification and methanation process and enabled a more stable microbial community. This study demonstrated that electro-fermentation is an efficient way to treat high-concentration potato starch industrial wastewater for methane production.

Effects of food wastes based on different components on digestibility and energy recovery in hydrogen and methane co-production

This study was conducted for four organic fractions (carbohydrates, proteins, cellulose, lipids) at an inoculum concentration of 30 % and a total solid (TS) of 8 % to investigate the effect of the main components of food waste on the performance of the two-stage anaerobic digestion. The results showed that the gas phase products were closely related to the composition of the substrate, with the carbohydrate and lipid groups showing the best hydrogen (154.91 ± 2.39mL/gVS) and methane (381.83 ± 12.691mL/gVS) production performance, respectively. However, the increased protein content predisposes the system to inhibition of gas production, which is mutually supported by changes in the activity of dehydrogenase and coenzyme F420. Butyric acid (53.19 %) dominated the liquid phase products in both stages, indicating that all four organic fractions were butyric acid-based fermentation and that the final soluble chemical oxygen demand degradation reached 72.97 %–82.86 %. The carbohydrate and cellulose groups achieved the best energy recovery performance, with conversion rates exceeding 65 %. The above results can provide a useful reference for the resource utilization of food waste.

Constructing bimetal, alloy, and compound-modified nitrogen-doped biomass-derived carbon from coconut shell as accelerants for boosting methane production in bioenergy system

Accelerants can enhance methane production in biomass energy systems. Single-component accelerants cannot satisfy the demands of anaerobic co-digestion (AcoD) to maximize overall performance. In this work, nitrogen-doped bio-based carbon derived from coconut shells, containing bimetallic Ni/Fe nanoparticles, FeNi3 alloys, and compounds (Fe2O3, FeN, and Fe3O4), was constructed as hybrid accelerants (Ni-N-C, Fe-N-C, and Fe/Ni-N-C) to boost CH4 production and CO2 reduction. The cumulative biogas yield (553.65, 509.65, and 587.76 mL/g volatile solids), methane content (63.58%, 57.90%, and 67.39%), and total chemical oxygen demand degradation rate (60.15%, 54.92%, and 65.38%) of AcoD with Ni-N-C (2.625 g/L), Fe-N-C (3.500 g/L), and Fe/Ni-N-C (2.625 g/L) were higher than control (346.32 mL/g volatile solids, 40.13%, and 32.03%), respectively. These digestates with Ni-N-C, Fe-N-C, and Fe/Ni-N-C showed excellent stability (mass loss: 22.97%-32.75%) and total nutrient content (4.43%-4.61%). Based on the synergistic effects of the different components of the hybrid accelerant, an understanding of the enhanced methanogenesis of AcoD was illustrated.

Fabrication of Ti/SnO2-Sb electrodes containing RuO2 interlayer for efficient electrocatalytic oxidation of caprolactam wastewater

The low effectiveness and poor endurance of the electrodes prevent electrocatalytic oxidation from being widely used to treat organic chemicals in wastewater.Here, the coating pyrolysis process was used to successfully create a Ti/SnO2-Sb containing an interlayer of RuO2. The Ti/RuO2/SnO2-Sb surpassed the conventional Ti/SnO2-Sb in both electrocatalytic activity and electroactive surface area. The Ti/RuO2/SnO2-Sb have higher oxygen evolution potential(OEP), better coverage, lower resistance, and less energy consumption with the introduction of RuO2 interlayer. Moreover, the Ti/RuO2/SnO2-Sb exhibited 1.88 times the rate constant of chemical oxygen demand(COD) degradation in caprolactam wastewater furthermore a 25 times rise in service life over conventional Ti/SnO2-Sb.

Removal of organic pollutants from sugarcane stillage using UV-assisted Fenton process

Stillage or distillery wastewater have been reported as industrial effluent that are difficult to be treated as its discharge in the water bodies presents contamination with recalcitrant and non-degradable pollutants. Due to their complicated structure, stillage treatment process using traditional methods such as adsorption, coagulation, and flocculation is challenging. Fenton reaction has been found as an effective method to degrade these contaminants through hydroxyl radicals. In this study, the removal of pollutants in stillage was investigated using UV-assisted Fenton process. Experiments was conducted for 60 minutes in a batch reactor with initial pH of stillage 4.5, UV lamp of 395-400 nm, and constant speed of 250 rpm, while the dosages of H2O2 and Fe (II) were kept constant at 3.3 g/L and 0.6 g Fe/L, respectively. The profile of chemical oxygen demand (COD) removal, pH, temperature, and oxidation-reduction potential (ORP) was evaluated under three dilution factors of raw stillage (1/10; 1/25; and 1/50) during treatment process to investigate the effects of these parameters on treatment efficiency. It has been observed that initial COD of stillage had considerable effect on the performance of UV-photo-Fenton treatment, as higher dilution factor increases the removal efficiency of COD from stillage. The degradation of COD by UV-assisted Fenton was found to be suitably described by the pseudo-first-order kinetics. The results obtained from this work indicated that UV-Fenton can be introduced as a successful advanced treatment process for efficient degradation of stillage.