Phenol Removal Efficiency Research Articles

Integration of carbon microcapsules with beef omasum like shells by interconnected Macropores for removal of phenol from aqueous solution

A bulk carbon adsorbent with a bionic structure was synthesized based on wrinkled silica microspheres colloidal crystal templates (WSMs-CCTs). As a result, the carbon microcapsules with the internal structure of beef omasum are closely integrated by interconnected macropores to form the bulk carbon adsorbent (ICM-BO). ICM-BO was further applied as a phenol adsorbent to achieve efficient phenol removal. Compared with the reported adsorbents, ICM-BO with excellent adsorption capacity and reusability are attributed to the hierarchical nanoscale needle-like structure of the inner walls, interconnected macropores, and the robust monolith nature. The isothermal adsorption process can be well described through the Liu model with a maximum proposed absorption value of 504. 8 mg g−1 at 318 K. In addition, the morphology of ICM-BO is maintained and the regeneration efficiency (RE) is relatively stable after 10 cycles, indicating that ICM-BO has excellent reusability. Notably, in the simulated industrial effluent experiment, the removal rate of phenolic compounds by ICM-BO reach 93.5%, indicating that the ICM-BO is hardly affected by other components and has excellent adsorption capacity, which is expected to be an ideal choice for the adsorption of phenols.

Multi-functional core-shell pomegranate peel amended alginate beads for phenol decontamination and bio-hydrogen production: Synthesis, characterization, and kinetics investigation

Phenolic compounds discharged from different industries comprise a great threatening to environmental system and human health. They are toxic even at a low concentration (<1.0 μg/L). Adsorption is attractive scenario for successful removal of phenolic compounds from wastewater. Herein, a facile strategy was employed to fabricate amended alginate beads based on pomegranate peel. The constructed beads were intensively scrutinized, and introduced for the remediation of phenol from wastewater under various operational parameters of pHi (e.g., 2.1–10.7), adsorbent dose (e.g., 0.5 – 5.0 g L−1), initial phenol concentrations (e.g., 10.0 – 500.0 mg L−1), and residence time (e.g., 5.0 – 270.0 min). Consequently, the efficacy of bio-hydrogen production via dark fermentative process of co-substrate metabolism of phenol and glucose in presence of beads was systematically inspected. Our findings revealed that the maximum adsorption capacity of beads was 119.048 mg g−1 at pH 7.2. Comfortingly, the fitting isotherms experiments expounded that the adsorption of phenol by beads conformed to the Langmuir model. The kinetics modelling findings matched with pseudo-second-order model. Otherwise, the as-prepared beads have remarkably improved anaerobic co-substrate fermentation process of glucose (synergism) and phenol removal efficiency (91.1–97.0%), with bio-hydrogen yield of 0.35 up to 2.65 mol-H2 mol−1 glucose. Overall, the present study illustrates an ample perspective of natural resources feasibility as a futuristic rational platform for wastewater decontamination and bio-hydrogen production.

Exploring the potential of metal oxides as cathodic catalysts in a double chambered microbial fuel cell for phenol removal and power generation

Detection of high phenol concentrations in industrial wastewater contributed to the need for more efficient wastewater treatment approaches. This study compared and investigated the different metal oxides as cathodic catalysts in a double chambered microbial fuel cell (MFC) for simultaneous phenol removal and bioelectricity generation. Metal oxides such as copper (II) oxide (CuO), manganese dioxide (MnO2) and tin (IV) oxide (SnO2) were synthesized and loaded on a carbon (C) plate, respectively, for application as cathode in the MFC. Results revealed that total chemical oxygen demand and phenol removal efficiency of MFC depleted in the order of CuO/C (96.69 and 100 %) > β-MnO2/C (90.93 and 94.41 %) > α-MnO2/C (84.69 and 90.17 %) > SnO2/C (80.25 and 84.84 %) > bare C (70.48 and 77.06 %) cathode due to the deterioration in the oxygen reduction reaction reactivity. Besides, the solution pH was crucial in determining the catalyst's surface charge properties. At pH 8, higher solution conductivity and stronger electrostatic attraction between positively charged CuO and anionic phenol molecules were favourable for the complete phenol removal. This phenomenon contributed to a 1.77-fold higher maximum power density attained at pH 8 (29.24 mW m−2) than that of pH 11 (16.52 mW m−2) due to more electrons could be utilized for electricity generation. This study provided valuable information on the facile fabrication of cost-effective cathodic catalysts in a double chambered MFC for wastewater treatment and bioelectricity generation.

Broadening the pH range of molecular oxygen activation for zero-valent aluminum by ball-milling surface modification

In the zero-valent aluminum (Al0)/O2 system, due to the oxide film covering the Al0 surface and secondary passivation occurring during the reaction, the drawbacks of long induction period (∼2 h) and requiring strong acidic conditions (pH < 4) limit its wide application. It is possible to achieve efficient activation of molecular oxygen over a wide pH range for Al0 by ball milling (BM) surface modification. In this study, a novel wide-pH-applicable and zero-induction-period Al0-based composite was synthesized with one-pot BM method by directly mixing solid-phase microscale Al0, ethylenediaminetetraacetic acid ferric sodium salt (FeEDTA) and carbon nanotubes (CNTs). The excellent performances under different reaction conditions and the characterizations of Al0-based composite were analyzed. At initial pH of 2–10, the removal efficiency of phenol by Al0-based composite was more than 95% under atmospheric conditions without any induction period. Through BM process, the oxide layer of Al0 was destroyed by FeEDTA and further activating Al0 surface and increasing its reactivity. Meanwhile, CNTs were attached on the fresh Al0 surface to prevent secondary passivation and catalyze the reduction reaction between inert Al0 and O2. This study provides a green and convenient strategy for realizing the extensive application of Al0/O2 system.

Enhanced carrier separation in g-C3N4/MoO3-x heterostructures towards efficient phenol removal

Two-dimensional (2D)/2D g-C3N4/MoO3-x heterojunctions were constructed for enhanced photocatalytic phenol removal. The oxygen vacancies in MoO3-x help to extend absorption in a full solar spectrum especially in near-infrared (NIR) region. Improved charge transfer path preserved photogenerated electrons and holes with powerful enough redox abilities, which simultaneously improved phenol photodegradation performance and photocatalytic activation efficiency of peroxydisulfate (PDS). In full solar spectrum activated PDS system, the phenol removal efficiency using g-C3N4/MoO3-x heterostructures reached 98% within 60 min. For the contribution of PDS activation process, active species trapping experiment and in-situ open-circuit potentials (OCP) measurement indicated that radical and non-radical pathways jointly promoted the elimination of phenol. The existence of oxygen vacancies promoted the formation of catalyst-PDS* complex and thus facilitated the electron transfer process, which exerted crucial effect as non-radical pathway. This result provided an ideal catalyst for photocatalytic persulfate activation system in the field of environmental remediation.

GO-Fe3O4-CeO2-CTAB nanocomposite as a high-performance adsorbent for removal of phenol from aqueous solutions

ABSTRACT This study aimed to assess GO-Fe3O4-CeO2-CTAB nanocomposite adsorption efficiency for removing the phenol molecules from the aqua solution. The researcher performed the batch investigations to estimate the percentage of phenol removal from wastewater with the variation of pH value from 3 to 10, adsorption time from 5.000 to 100.000 min, the adsorbent dose from 0.003 to 0.040 g, the phenol concentration from 20.000 to 440.000 mg L−1 and temperature from 25 to 60°C. The GO-Fe3O4-CeO2-CTAB nanocomposite produced by a Co-precipitation method was used to adsorb and remove phenol molecules from an aqueous solution. The synthesised nano-sorbent was investigated by different methods including FTIR, XRD, SEM, EDX, VSM and BET techniques. The gained data show that the best removal efficiency of phenol by GO-Fe3O4-CeO2-CTAB nanocomposite was obtained at pH = 8, the absorbent dosage of 400.000 mg L−1 (0.020 g), contact time = 60 min and temperature of 25°C. For the equilibrium study, based on the obtained coefficients correlation of definition from fitted models, the highest value is obtained for the Langmuir model, (KL = 0.048 L mg−1, qm = 492.000 mg g−1, RL = 0.509 and R2 = 0.992), so, phenol adsorption on the surfaces of GO-Fe3O4-CeO2-CTAB nanocomposite was a monomolecular adsorbed layer. Based on obtained R2 values, it can be concluded that the pseudo-second-order kinetic model seemed to be match well with the adsorption of phenol molecules at the surface of GO-Fe3O4-CeO2-CTAB nanocomposite in three concentrations of 50.000, 100.000 and 125.000 mg L−1 (qe2 = 52.080, 103.090 and 129.870 mg g−1, k2 = 0.005, 0.003 and 0.002 g mg−1 min−1, R2 = 0.999, 0.999 and 0.999 respectively).

Phenol removal by activation of persulfate using magnetic carbon generated from sludge and steel converter slag

We obtained the best sample of Steel Sludge Carbon-Sludge Carbon (SCS@SC0.5–800 °C), which was subsequently used as a catalyst to activate persulphate for the removal of phenol. The batch experimental results illustrate the phenol removal efficiency reached 98.8% and the constants were 0. 25515 min−1 in the optimal SCS@SC0.5–800 °C/persulfate system (SCS@SC0.5–800 °C = 0.4 g/L; persulfate = 2 mM; phenol = 20 mg/L; pH=7). Increasing the reaction temperature increases the effectiveness of the system in removing phenol, and cations have a slight inhibitory effect on the removal of phenol from the system. Repeatability tests showed that after the third cycle, the phenol removal rate decreased from 88.6% to 65.2%, and the kobs decreased from 0.12567 min−1 to 0.03105 min−1. These results may be explained by the fact that active ingredients such as Fe0 are constantly removed from the solution, reducing the efficiency of the degradation process. The removal mechanism suggests that phenol is enriched on the graphitic carbon surface and subsequently degraded by leaching Fe2+-activated persulfate to produce free radicals. This study details the preparation of optimal samples of this new green catalyst and broadens the scope and potential of the catalyst for practical applications.

A study on the efficiency of the sequential batch reactor on the reduction of wastewater pollution from oil washing.

Industrial pollution discharges from washing fuel oils pose severe problems for the environment, particularly for the marine environment receiving these discharges. This work evaluates the biological treatment performance of wastewater (90 m3/h) rich in organic matter with low biodegradability using a sequential batch reactor (SBR) on a laboratory scale. The test using SBR was carried out for 25days on a continuous cycle of 24h (30min of filling, 17h of aeration, 4h of anoxia, 2h of settling, and 30min of emptying). The feasibility of alternative sources of microorganisms from urban wastewater. The performance of the batch sequencing reactor was evaluated using turbidity, total suspended solids, chemical oxygen demand (COD), biological oxygen demand (BOD), ammonium, nitrate, and phenol as indicators. The results obtained showed that the COD/BOD ratio and the pollutant load vary from one campaign to another. The removal efficiency of COD, BOD, TSS (Total suspended solids), ammonium, nitrate, and phenol varies from 81%, 91%, 72%, 100%, 52%, and 63%. Thus, SBR-type treatment could be an interesting way to reduce pollution due to its simplicity, less space occupation, low energy consumption, and not requiring highly qualified personnel.

Coinstantaneous removal of nitrate and phenol by modified corncob and manganese dioxide based immobilized bioreactor: Enhancement and microbial synergistic mechanisms

In this study, polyvinyl alcohol (PVA), modified corncob powder and manganese dioxide (PCCM) cubes were prepared for entrapping Cupriavidus sp. ZY7 and Pantoea sp. MFG10 in the bioreactor. The denitrification and phenol removal efficiencies reached 89.38% and 89.17% at carbon to nitrogen (C/N) ratio of 1.0, hydraulic retention time (HRT) of 6 h, and the nitrate and phenol concentration of inflow was 15 and 1 mg L−1, respectively. Strain ZY7 could degrade cellulose in corncob to provide available carbon source in the bioreactor, and the enhancement effect was more obvious as C/N ratio increased. High-throughput data confirmed that Cupriavidus and Pantoea were the prevalent strains in the PCCM cubes bioreactor. The synergistic relationship between strains ZY7 and MFG10 was the key to the excellent pollutants removal ability of the bioreactor at low C/N ratio, which was important for the treatment of wastewater with complex contaminants.

Investigating the phenol removal from aqueous media by photocatalytic magnetized graphene oxide nanocomposite

AbstractAs a large and diverse group of secondary metabolites, phenolic compounds are one of the most common chemical pollutants present in water resources. these compounds can have toxic effects on ecosystems and humans. Therefore, their removal from water sources appears to be of great importance. In this study, a magnetic graphene oxide (MGO) photocatalyst was synthesized and used to remove phenol from water. The fabricated GO magnetic nanocomposites were determined by SEM and FTIR techniques. Afterward, these nanoparticles were used to remove phenol from aquatic media considering different operational parameters, including pH of the solution, initial concentration of phenol, contact time, and adsorbent dosage. The results showed that the magnetized GO nanoparticles could remove 90.83% of phenol molecules under the optimal conditions of solution pH = 3.0, initial phenol concentration of 20 mg/L, adsorbent concentration of 300 mg/L, and contact time of 120 min. additionally have compared the results of UV, Fe3O4/GO, and Fe3O4/GO/UV on the removal of phenol under optimum conditions. Accordingly, the phenol removal efficiencies for UV alone, Fe3O4/GO, and Fe3O4/GO/UV were obtained at 4.5, 65.73, and 90.83%, respectively. Based on the findings, the prepared magnetic GO nanoparticles have extended capabilities such as easy and rapid separation from sample and high potential in removing phenolic compounds, so, it can be introduced as an appropriate adsorbent for removal of this pollutant from water and wastewater.

CuBi2O4 surface-modified three-dimensional graphene hydrogel adsorption and in situ photocatalytic Fenton synergistic degradation of organic pollutants

A CuBi2O4/rGH composite catalyst was prepared by modifying CuBi2O4 on the surface of a three-dimensional graphene hydrogel (rGH) via a simple water bath method. The large specific surface area and particular surface adsorption properties of rGH were beneficial for adsorbing and enriching pollutant molecules and could then be further degraded by the in situ photocatalytic Fenton synergistic effect with the addition of H2O2. The introduction of graphene not only increases the surface area and improves the adsorption properties but also accelerates the transfer and separation efficiency of the interface photogenerated charge, thereby promoting the photocatalytic Fenton degradation performance. The adsorption performance and catalytic degradation performance of the 20 % CuBi2O4/rGH composite for phenol were 1.4 and 1.3 times higher than those of CuBi2O4, respectively. Meanwhile, the removal efficiency of phenol in the adsorption and in situ photocatalytic Fenton synergistic system was as high as 80 % within 20 min. In addition, the cross-linked network structure of the 3D graphene hydrogel could be better recycled, which has significant potential in practical applications. Quenching and EPR experimental results showed that hydroxyl radicals (·OH) were the most active species in the synergistic degradation process, and the mechanism of CuBi2O4/rGH adsorption and in situ photocatalytic Fenton degradation was proposed.

Preparation, performance and mechanism of metal oxide modified catalytic ceramic membranes for wastewater treatment.

Catalytic ceramic membranes (CMs) integrated with different metal oxides were designed and fabricated by an impregnation-sintering method. The characterization results indicated that the metal oxides (Co3O4, MnO2, Fe2O3 and CuO) were uniformly anchored around the Al2O3 particles of the membrane basal materials, which could provide a large number of active sites throughout the membrane for the activation of peroxymonosulfate (PMS). The performance of the CMs/PMS system was evaluated by filtrating a phenol solution under different operating conditions. All the four catalytic CMs showed desirable phenol removal efficiency and the performance was in order of CoCM, MnCM, FeCM and CuCM. Moreover, the low metal ion leaching and high catalytic activity even after the 6th run revealed the good stability and reusability of the catalytic CMs. Quenching experiments and electron paramagnetic resonance (EPR) measurements were conducted to discuss the mechanism of PMS activation in the CMs/PMS system. The reactive oxygen species (ROS) were supposed to be SO4˙- and 1O2 in the CoCM/PMS system, 1O2 and O2˙- in the MnCM/PMS system, SO4˙- and ·OH in the FeCM/PMS system, and SO4˙- in the CuCM/PMS system, respectively. The comparative study on the performance and mechanism of the four CMs provides a better understanding of the integrated PMS-CMs behaviors.

The Fragmented 3d-Covalent Organic Framework in Cellulose Acetate Membrane for Efficient Phenol Removal

The Fragmented 3d-Covalent Organic Framework in Cellulose Acetate Membrane for Efficient Phenol Removal

Influence of co-substrate existence, temperature, pH, and salt concentration on phenol removal, desalination, and power generation using microbial desalination cells

Microbial desalination cells (MDCs) exhibited an economical value with large promises as a useful desalination treatment solution. MDCs threefold applications to efficiently treat wastewater and to produce electricity and simultaneously accomplish desalination were investigated in this work. The study examined the influence of various performance parameters including co-substrate, temperature, pH, and salt concentrations on the response of three-chamber MDCs with respect to energy recovery and contaminant removal (Phenol). The system evaluation criteria encompassed chemical oxygen demand (COD), phenol removal efficiency, Coulombic efficiency, desalination efficiency, and other system parameters such as voltage generation and power density. The maximum COD and phenol removal efficiencies obtained at temperature = 37 °C, pH = 7, and salt concentration = 10,000 ppm, were 80% and 74%, respectively. The maximum Coulombic efficiency was 5.3% and was observed at temperature = 18 °C, pH = 7, and salt concentration = 10,000 ppm. The results show that the presence of a co-substrate improved power density; the maximum power density obtained was 52.9 mW/m2. The principal component analysis elucidated the impact of pH on COD and phenol removal rates. With our findings confirmed trends in the improvement of the voltage generation, COD and phenol removal efficiencies with the addition of a co-substrate, the temperature and pH increase.

High removal efficiency of volatile phenol from coking wastewater using coal gasification slag via optimized adsorption and multi-grade batch process

Abstract Powder adsorbent made by coal gasification slag (CGS) was used to adsorb pollutants from coking wastewater (CW). This study initially focused on the removal efficiency of volatile phenol, NH3–N, and chemical oxygen demand (COD) from CW. The removal rate of volatile phenol increased from 48.90% to 70.50% after acid precipitation of CW by 4.0 mL reagent of sulfuric acid (3.0 M) and optimization of adsorption process by central composite design-response surface methodology with optimized conditions. Volume ratio of liquid and solid adsorbent (V L/S) and pH were the significant factors in the adsorption process. Batch experiment improved the volatile phenol, NH3–N, and COD removal rate to 85.1%, 41.6%, and 77.3%, respectively. Multi-grade batch process in grade 3 made a further promotion of pollutants removal rate as 98.5%, 73.6%, and 80.5%, respectively. Scanning electron microscope-energy dispersive spectrum and Fourier-transform infrared spectrometer were used to confirm the adsorption effect. CGS-based adsorbent for CW treatment has potential advantages due to the features of good adsorption performance and low cost.

Phenol removal from aqueous environments by natural &amp; chemically modified kaolin clay

AbstractNatural, acid and base modified kaolin clays were studied for the sake of phenol and 4‐chlorophenol removal from aqueous environments and their application to real ground and industrial wastewater samples. Scanning electron microscope (SEM), infrared spectroscopy (IR), X‐ray diffraction (XRD), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), and Surface area analysis were employed for characterization of the adsorbents microstructure. Operating factors such as adsorbent dose, solution pH, initial phenol concentration, and contact time were studied. The experimental data displayed that the increase of the adsorbent dose, contact time, and pH value from 2 to 7 increases the efficiency of the removal process. Optimal conditions for phenolic removal were; contact time of 300 min, primary phenol solution of 25 mg/L, pH 7 and 2.5 g/L as an appropriate adsorbent dose using crude (natural), acid modified and base modified kaolin clays. The higher phenolic removal efficiencies were obtained at 5 mg/L as 90, 97, 96.2%, respectively, for the adsorbents in the previously mentioned order. The adsorption capacity in the removal of phenol and 4‐chlorophenol were 7.481 and 4.195, 8.2942 and 3.211, and 8.05185 and 18.565 mg/g, respectively, for the adsorbents in the same mentioned order. The adsorption equilibrium data were fitted and analyzed with four isotherm models, namely, Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. The adsorption process of phenol on studied adsorbents was exothermic, spontaneous and thermodynamically favorable proved by the negative values of their thermodynamic parameters ΔH° and ΔG°. The correlation coefficient (R2) for all concentrations was higher than 0.94, which indicates that in the studied system, the data suitably fit the first‐order kinetics. The % desorption capacity was amounted to 96%, 91.11%, and 87.06% of adsorbed phenol, respectively, for the adsorbents in the previous order using 0.1N NaOH and 10% V/V ethanol solutions as eluents at 25°C, indicating the reusability of the adsorbents. Kaolin and its modified forms can be introduced as eco‐friendly and low‐cost adsorbents in water remediation implementation.

Construction of magnetically recoverable MnZnFe2O4@Ag3PO4 Z-scheme photocatalyst for rapid visible-light-driven phenol degradation.

Visible-light-driven magnetic heterojunction as a promising photocatalysts has received much attention in environmental remediation. In this work, novel Z-scheme heterojunction MnZnFe2O4@Ag3PO4 (MZFO@APO) magnetic photocatalysts with excellent visible-light-driven photocatalytic activity are successfully constructed and characterized. The photocatalytic activity for phenol degradation is measured, and photodegradation mechanism is investigated with EPR, radical trapping experiments, and LC-MS. It turns out that the heterojunction introduced MZFO exhibits good adsorption effect on visible light and the direct Z-scheme bandgap alignment of MZFO and APO significantly improves charge separation and electron transfer, outperforming that of pure APO. MZFO@APO-40% with 40% APO content shows the rapid photodegradation performance, obtaining a 100% removal efficiency of phenol (25mg L-1) after 12-min visible light irradiation, and its kinetic constants are approximately 25.3 and 4.9 times higher than that of P25 TiO2 and pure APO, respectively. Especially, MZFO@APO-40% also possesses a high magnetic separation property and can be efficiently reused for 5 cycles. Additionally, EPR and radical trapping experiments confirm that h+, O2-, and 1O2 are the main active species in the photocatalytic process. Hydroquinone and small molecular organic acids such as maleic acid and oxalic acid are detected by LC-MS, which further indicates that the pathway of phenol degradation involves hydroxylation, open-ring reactions, and mineralization reactions. The novel addition of MZFO in photocatalyst construction has the potential to promote its application in environmental remediation.

Coupling phenol bioremediation and biodiesel production by Tetradesmus obliquus: Optimization of phenol removal, biomass productivity and lipid content

There is a growing interest for the utilization of microalgae in the bioremediation of organic pollutants and the use of biomass as a biofuel feedstock. This study investigated the influence of phenol exposure and culture conditions on the phenol removal efficiency, biomass productivity and lipid contents of Tetradesmus obliquus. Plackett-Burman design identified CaCl2, NaNO3, and initial phenol concentration as the most important variables affecting on phenol removal. The optimum conditions to maximize biomass productivity, phenol removal and lipid content were determined using the Box-Behnken experimental design as 150.1 mg L−1 phenol, 0.1 g L−1 NaNO3, and 0.03 g L−1 CaCl2. Under these conditions, phenol was completely removed from the optimized medium after 3 days and the biomass productivity and lipid content were 19.53 mg L−1 day−1 and 27.85% (w/w) after 10 days, respectively. Phenol treatment promoted algal biomass productivity to ∼1.3-folds and lipid productivity to ∼ 1.6-folds higher than the control treatment without adding phenol (negative control). Additionally, phenol altered the fatty acid methyl ester composition and increased the saturated and polyunsaturated fatty acid contents with concomitant decrease in the monounsaturated fatty acids. The predicted biodiesel characteristics viz. iodine value, cetane number, oxidation stability, kinematic viscosity, and flash point, in the presence of phenol were in accordance with the international standards. Accordingly, the present study indicated that phenol could be effectively bioremediated by T. obliquus with simultaneous promotion of the algal biomass and lipid productivity for biofuel production.

Syntrophic acetate oxidation having a key role in thermophilic phenol conversion in anaerobic membrane bioreactor under saline conditions

Phenol conversion under saline thermophilic anaerobic conditions requires the development and sustenance of a highly specialized microbial community. In the present research, an anaerobic membrane bioreactor (AnMBR) fed with an influent containing 0.5 g·L−1 phenol and 6.5 gNa+·L−1 was operated at 55 °C for 300 days. Phenol degradation was limited when phenol was the sole substrate. However, the phenol removal efficiency significantly (p < 0.001) increased to 80 % corresponding to a conversion rate of 29 mgPhenol·gVSS−1d−1 when acetate (0.5 gCOD·L−1) was simultaneously provided. Isotopic analysis using 1–13C labeled acetate and measuring 13CH4 revealed that acetate was first oxidized to hydrogen and CO2, prior to methanogenesis, resulting in an increased abundance of hydrogenotrophic methanogens. It is hypothesized that the latter is of crucial importance for achieving effective anaerobic oxidation of phenol and its metabolites. Remarkably, the phenol conversion rate in the membrane-associated biomass was three times higher than in the suspended biomass. The observed difference in the conversion rate could be explained by the presence of an increased abundance of hydrogenotrophic methanogens in the membrane-associated biomass confirmed by a microbial community analysis of Archaea. Benzoate was measured in the permeate suggesting that phenol degradation occurred via the benzoyl-CoA pathway. The results of the current study suggest that syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis, which results in the presence of an abundant electron sink, plays a key role in enhancing thermophilic phenol degradation. The obtained insights widen the application of anaerobic digestion to treat saline phenolic-rich wastewater at high temperatures.

Electro‐oxidation of pistachio processing wastewater using Ti/Pt mesh‐type anodes in batch system

AbstractIn this study, the treatment of pistachio processing wastewater (PPW) by electro‐oxidation method was investigated. Ti/Pt‐plated electrodes were used for the anode material, and stainless steel electrodes were used for cathode material. Experimental studies were carried out in batch mode. Stirring speed, supporting electrolyte species and concentration, initial pH value, current density, temperature and dilution ratio were selected as experimental parameters effecting removal efficiency. In Ti/Pt electrode experimental studies on the optimum conditions, chemical oxygen demand (COD), total organic carbon (TOC) and total phenols (TP) removal efficiencies were obtained, respectively, as 99.98%, 70.74% and 100%, and energy consumption value was obtained as 297.5 kW‐h/m3 (12.39 kW‐h/kg COD, 51.29 kW‐h/kg TOC and 64.68 kW‐h/kg TP). As a result of the experimental studies, the PPW can be treated by electro‐oxidation. Given the results of removal efficiency and energy consumption values, it was concluded the electro‐oxidation using Ti/Pt anode very appropriate treatment of PPW.