Maximum Phenol Removal Research Articles

Isolation and Characterization of Yarrowia lipolytica YQ22 from Diesel Samples for Phenol Biodegradation

Phenolic compounds have gained international interest due to their carcinogenic, toxic, and bioaccumulative properties, causing adverse effects in both animals and humans. As a result, there is a growing interest in finding alternative and eco-friendly treatment routes for phenol by exploring new microbial cultures with potential adaptation and biodegradation capabilities. In this study, the phenol removal efficiency of Yarrowia lipolytica YQ22 under laboratory conditions was determined. The YQ22 strain was obtained from diesel samples from a fuel station in Trujillo, Peru, isolated through serial dilutions on Sabouraud agar, and identified through its morphological characteristics using microscopy and molecular analysis by polymerase chain reaction of the ribosomal DNA internal transcribed spacer (ITS) and 5.8S regions. In the treatment, the effect of pH (5, 6 and 7) and temperature (25°C, 30°C and 35°C) on phenol removal with 2% (v/v) inoculum of Yarrowia lipolytica from 48-hour growth was evaluated. Phenol concentration was measured by high-performance liquid chromatography. A maximum phenol removal percentage of 61.18 was obtained for YQ22 at 30°C, pH 5 and 120 rpm during 48 hours. These findings demonstrate the ability of Yarrowia lipolytica to remove phenol and suggest its potential use in the field of bioremediation of phenolic compounds and their derivatives.

Sustainable waste utilization: Geopolymeric fly ash waste as an effective phenol adsorbent for environmental remediation

Rapid industrialization and urbanization generate significant waste, including fly ash, posing environmental challenges. Utilizing these materials is essential to mitigate impacts and promote sustainable development. This research paper focuses on the innovative application of geopolymeric fly ash (GEOFA) waste modified with titanium oxide (TiO2) (GEOFA-TiO2) as a promising adsorbent for the removal of phenol compounds from contaminated water. Analysis showed that the modification process resulted in the formation of functional groups such as -OH, which aided in the adsorption process. Adsorption studies were conducted to evaluate the influence of pH, temperature, and concentration on phenol removal. The maximum percentage removal of phenol was achieved at optimum conditions of pH 6 and a temperature of 25 °C, with an adsorption capacity of 166.7 mg/g. The adsorption process followed the Langmuir model, suggesting a monolayer adsorption mechanism and the thermodynamic studies revealed that the phenol adsorption onto GEOFA-TiO2 was an endothermic process with a promising affinity between phenol and the adsorbent. This study demonstrates the effective use of modified fly ash-based adsorbents to remove phenolic contaminants. By repurposing waste materials, this research addresses waste management challenges and promotes sustainable practices, reveling their potential for environmental remediation.

Intensifying of phenol removal from aqueous solutions using ACTF as a hybrid carbon nanostructure: Isotherms, kinetics and thermodynamics study

Activated carbon thin film (ACTF) was prepared via a single-step mixing method through thermal fabrication that was utilized for the removal of phenol in the batch aqueous media. The prepared adsorbent was characterized using TEM, XRD, FTIR, BET, EDX, Raman, and TGA analyses. Batch adsorption experiments were studied by using the effects of different parameters such as pH, temperature, dose, contact time, and initial concentration of phenol solution on adsorption. The maximum phenol removal by ACTF was approximately 89.5% at pH 4, adsorbent dose of 1 g/L, and 50 ppm for the initial concentration of phenol at room temperature through 150 min. Adsorption data were modeled using four adsorption isotherm models (Langmuir, Freundlich, Temkin, and D-R) and three kinetic models (pseudo first order, pseudo second order, and Intraparticle diffusion) using linear and non-linear regression methods. The chi-square (X 2) and the correlation coefficient (R 2) were both used as error analysis techniques to find the best-fitting equations. The results showed that phenol adsorption on ACTF adsorbent fitted more accurately with nonlinear regression models, which is consistent with Freundlich isotherm and pseudo-second order form. Also, thermodynamic results demonstrated that attachment of phenol onto ACTF adsorbent was spontaneous (negative value of ΔG) and exothermic (negative value of ΔH) with decreasing temperature from 55 °C to 25 °C. Synthesized ACTF showed good regeneration capacity with 0.1 M NaOH as the eluent, making it an appropriate adsorbent for the elimination of phenol. This study evidenced the efficacy of ACTF as a phenol adsorbent.

Phenol adsorption properties and microstructural changes of organically modified bentonite

Phenolic compounds are prevalent organic contaminants in aquatic and soil environments. To address the issue of phenolic waste water treatment, bentonite can be utilised as an effective adsorbent through organic modification. The present study focuses on using sodium bentonite, which was modified with cetyltrimethylammonium bromide (CTMAB), to remove phenol from an aqueous solution. The influence of various factors such as adsorption time, initial phenol concentration and CTMAB–bentonite dosage on phenol adsorption was thoroughly investigated. In addition, the microstructural changes during the adsorption process, adsorption kinetics and adsorption isotherms of the organically modified bentonite (OMB) were analysed. The results indicated that the adsorption equilibrium time of OMB was longer compared with that of sodium bentonite. The amount of phenol adsorbed by OMB was found to be positively correlated with the initial phenol concentration and CTMAB–bentonite dosage. The maximum phenol adsorption capacity and removal rate achieved were 3.00 mg/g and 43.74%, respectively. The study also revealed that a quasi-second-order kinetic model was appropriate for describing the phenol adsorption process of OMB, and the adsorption isotherm was found to conform with the Freundlich isotherm model. These findings demonstrate the potential of OMB as an efficient and effective adsorbent for phenolic waste water treatment.

Characterization and Biodegradation of Phenol by Pseudomonas aeruginosa and Klebsiella variicola Strains Isolated from Sewage Sludge and Their Effect on Soybean Seeds Germination.

Phenols are very soluble in water; as a result, they can pollute a massive volume of fresh water, wastewater, groundwater, oceans, and soil, negatively affecting plant germination and animal and human health. For the detoxification and bioremediation of phenol in wastewater, phenol biodegradation using novel bacteria isolated from sewage sludge was investigated. Twenty samples from sewage sludge (SS) were collected, and bacteria in SS contents were cultured in the mineral salt agar (MSA) containing phenol (500 mg/L). Twenty colonies (S1 up to S20) were recovered from all the tested SS samples. The characteristics of three bacterial properties, 16S rDNA sequencing, similarities, GenBank accession number, and phylogenetic analysis showed that strains S3, S10, and S18 were Pseudomonas aeruginosa, Klebsiella pneumoniae, and Klebsiella variicola, respectively. P. aeruginosa, K. pneumoniae, and K. variicola were able to degrade 1000 mg/L phenol in the mineral salt medium. The bacterial strains from sewage sludge were efficient in removing 71.70 and 74.67% of phenol at 1000 mg/L within three days and could tolerate high phenol concentrations (2000 mg/L). The findings showed that P. aeruginosa, K. pneumoniae, and K. variicola could potentially treat phenolic water. All soybean and faba bean seeds were germinated after being treated with 250, 500, 750, and 1000 mg/L phenol in a mineral salt medium inoculated with these strains. The highest maximum phenol removal and detoxification rates were P. aeruginosa and K. variicola. These strains may help decompose and detoxify phenol from industrial wastewater with high phenol levels and bioremediating phenol-contaminated soils.

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.

Enhancement of Phenol degradation, using of novel Z-scheme Bi2WO6/C3N4/TiO2 composite: Catalyst and operational parameters optimization

A novel Z-scheme Bi2WO6/C3N4/TiO2 ternary heterojunction was successfully synthesized by the sol–gel / hydrothermal method. The photocatalytic activity of Bi2WO6/C3N4/TiO2 was investigated by the phenol degradation under simulated sunlight illumination. The Bi2WO6/C3N4/TiO2 ternary Z-scheme involving 30 wt% of TiO2, while Bi2WO6 to C3N4 mass ratio resulted in 65 to 35, was realized as an optimal composite and exhibited the best photocatalytic activity compared with individual g-C3N4, Bi2WO6/C3N4 and Bi2WO6/C3N4/TiO2 with different mass percentage ratios. The optimum amount of operating parameters were determined as: initial phenol concentration = 10 mg/L, pH = 7, catalyst dose = 1.5 g/L and irradiation time = 180 min. The maximum phenol removal efficiency in the presence of Bi2WO6/C3N4/TiO2 reached 84.7% at optimum conditions. The photocatalytic phenol degradation mechanism followed the first-order kinetic and the reaction rate of the ternary photocatalyst was around 2.18 and 1.34 times, higher than those of Bi2WO6 and Bi2WO6 / C3N4, respectively. In addition, all of the OH●, O2– ●, h+, and e- active species efficiently promoted the photocatalytic process. Complete mineralization took a place almost after 7.5 h from the beginning of the phenol photodegradation the synthesized Z-scheme exhibited excellent chemical constancy and reusability next to the five cycles of utilizations.

Promising Low-Cost Adsorbent from Waste Green Tea Leaves for Phenol Removal in Aqueous Solution.

Phenol is the most common organic pollutant in many industrial wastewaters that may pose a health risk to humans due to its widespread application as industrial ingredients and additives. In this study, waste green tea leaves (WGTLs) were modified through chemical activation/carbonization and used as an adsorbent in the presence of ultrasound (cavitation) to eliminate phenol in the aqueous solution. Different treatments, such as cavitation, adsorption, and sono-adsorption were investigated to remove the phenol. The scanning electron microscope (SEM) morphology of the adsorbent revealed that the structure of WGTLs was porous before phenol was adsorbed. A Fourier Transform Infrared (FTIR) analysis showed an open chain of carboxylic acids after the sono-adsorption process. The results revealed that the sono-adsorption process is more efficient with enhanced removal percentages than individual processes. A maximum phenol removal of 92% was obtained using the sono-adsorption process under an optimal set of operating parameters, such as pH 3.5, 25 mg L−1 phenol concentration, 800 mg L−1 adsorbent dosage, 60 min time interval, 30 ± 2 °C temperature, and 80 W cavitation power. Removal of chemical oxygen demand (COD) and total organic carbon (TOC) reached 85% and 53%. The Freundlich isotherm model with a larger correlation coefficient (R2, 0.972) was better fitted for nonlinear regression than the Langmuir model, and the sono-adsorption process confirmed the pseudo-second-order reaction kinetics. The findings indicated that WGTLs in the presence of a cavitation effect prove to be a promising candidate for reducing phenol from the aqueous environment.

Efficient treatment of phenol wastewater by co-culture of Chlorella vulgaris and Candida tropicalis

The increased water contamination with phenolic compounds has emerged as an important environmental concern due to their considerable ecotoxicities and associated health issues. Here, a co-cultured microalgae/microorganism system, Chlorella vulgaris and Candida tropicalis, has been developed for efficient treatment of phenol and microalgal biomass accumulation. Our results show that the C. vulgaris and C. tropicalis co-culture system can achieve the highest phenol removal rate as 233.3 mg/L/d and the total chlorophyll accumulation as 23.0 mg/L with the initial volume ratio of C. vulgaris and C. tropicalis at 1:3, which are 5.2 and 7.2 times higher than that of C. vulgaris monoculture respectively. The maximum phenol removal ability of the constructed co-culture system was tested as 1500 mg/L within 6 days. Transcriptome analysis suggested that the co-cultured C. vulgaris/C. tropicalis can utilize phenol as carbon source for its growth and metabolism, and the removal mechanism of phenol was mainly due to the biodegradation process other than bio-absorption. Simulated wastewater experiment shows that the co-culture system can not only efficiently remove the phenol compounds, also can significantly decrease the ammonia nitrogen (NH3−N), total phosphorus (TP) and chemical oxygen demand (COD) of wastewater with removal efficiencies as high as 93%, 92%, 80% and 100%, respectively. Our work provided a promising way for the treatment of phenol compounds and then promoting the growth of C. vulgaris using phenol containing wastewater.

Fenton like oxidative degradation of toxic water pollutants by iron nanoparticles synthesized via facile green route using waste iron rust as the iron precursor

Corrosion of iron by oxidation is a global problem that affects the economy and gives rise to environmental pollution. Iron rust is oxide or hydroxide of iron, it can be used as a secondary iron source which will lead to its management as well as reduce the pressure on primary iron sources. In the present study, waste iron rust was used as the precursor of iron for the synthesis of iron nanoparticles via the green route using extract of dried Jatropha leaf. Synthesized nanoparticles were characterized using different instrumental techniques. Synthesized iron nanoparticles bear an extremely large specific surface area of 190.2 m2/g. The catalytic potential of synthesized nanoparticles was tested for the degradation of toxic organic pollutants phenol and p-nitrophenol (PNP) in an aqueous solution. Both the pollutants were removed rapidly in the initial 30 minutes of the reaction time. Optimization of the removal process was done by varying different variables. Maximum removal of phenol (~98%) and PNP (~95%) was achieved at 0.1 g/L concentration of nanoparticles. The degradation reaction rate was determined by pseudo-first-order and pseudo-second-order kinetics and the data was found to be followed best by the pseudo-first-order kinetics.

Phenol removal by enhanced electrocoagulation process with persulfate salt

Introduction. Phenol is classified as priority pollutant. Phenol and its derivatives are stable in water, environmental contamination, and health concerns that are used as raw material in many chemical industries. This study investigated the removal of phenol by the reactivity of free sulfate radicals (SO4•–), activated by electrochemically generated Fe2+/Fe3+ ions which furthermore are evaluated to destroy phenol in aqueous solution.
 
 Materials and methods. In the present experimental study, electrocoagulation reactor by iron electrodes is used in the pre­sence of persulfate ions to phenol removing from aqueous solutions. In this regard, the effect of four independent variables including pH, electric current, persulfate dosage, and initial phenol concentration were studied on phenol removal.
 
 Results. The study determined the optimum conditions for maximum phenol removal using electro-persulfate process (EPS) as pH 3, 7.4 mM persulfate dosage, 27.78 mA/cm2 current density, and 100 mg/L initial phenol concentration at 30-min reaction time. The results showed that the efficiency of phenol removal was directly related to the initial persulfate dosage. In addition, the pH values, less than the phenol pKa, has slight effect onto the phenol removal. However, it was inversely correlated with a highly alkaline pH and higher phenol concentration.
 
 Conclusions. The study concluded that electro-persulfate process is an effective and robust process that can be used for handling of phenol containing wastewater.

Hybrid Photo-Fenton oxidation and biosorption for petroleum wastewater treatment and optimization using Box–Behnken Design

This study investigates the treatment of petroleum wastewater (PWTP) effluent using hybrid techniques (photo-Fenton oxidation and adsorption) to remove organic pollutants such as chemical oxygen demand (COD) and phenol. All the experiments were carried out in batch mode. The effects of pH, ferrous salt (Fe 2＋ ), and H 2 O 2 oxidation factors on the photo-Fenton process were studied. The response surface methodology (RSM) approach for experiment design and optimization yielded maximum COD and phenol removal at Fe 2＋ , H 2 O 2 , pH of 20 mM, 400 mM, and 3.8, respectively. In this optimal scenario, phenol reduction from the initial value of COD 12654.6 mg/L, phenol 213.0 mg/L was accomplished by 69.97% and 95.66%, respectively. Response surface methodology (RSM) photofenton based modeling and optimization was done using a Box–Behnken. The high coefficient of regression R 2 = 0 . 97 and 0.98 for COD and phenol oxidation is suggested by variance analysis (ANOVA). The PWTP effluent treated by Fenton oxidation with COD 4139.1 mg/L and phenol 70.1 mg/L was treated with Phragmites australis. Phragmites australis was chosen as an adsorbent. Phragmites australis was analyzed and characterized using several techniques, including Fourier transform infrared spectroscopy, Scanning Electron Microscopy, Zeta potential, and particle size distribution. The adsorption process step followed the photo-Fenton treatment process. The adsorption process achieved 69.04 % and 95.80% for COD and phenol removal. Kinetic studies showed that the statistics match very well in the nonlinear pseudo-first and second-order models based on the correlation coefficients (R 2 = 0 .999) and (R 2 = 0 .996), respectively, for COD and phenol removal in the adsorption phase. The severe adsorption potential for COD and phenol removal is 14421.97 mg/g and 374.90 mg/g, respectively. Finally, as a natural material, P. australis is a promising adsorbent material. • Box–Behnken Experimental Design (BBD) was used to determine the optimal removal efficiency for both COD and phenol for the photo-Fenton process. • Statistical analysis of the data indicated that H 2 O 2 significantly affected COD, phenol degradation for petroleum wastewater. • The optimum conditions for pH, Fe +2 , H 2 O 2 are 3.8, 20 mM, 400 mM for 69.97% COD, and 95.66% Phenol. • Phragmites australis was used as an adsorbent in the adsorption step. P. australis showed remarkable surface characteristics and adsorption ability. • The maximum adsorption capacity to remove COD and phenol of 14421.97, 374.90 mg/g, removal ratio 69.04%, and 95.80%, and the data fits very well in the nonlinear pseudo-first and second-order models.

Degradation Effect of UV Synergistic Biomass Activated Carbon Materials on Phenol Pollutants in Water

The purpose of the study is to purify the water containing phenol pollutants. The degradation effect of phenol pollutants in water is studied through the combined action of UV and biomass-activated carbon. First, the phenol solution is prepared in the laboratory to simulate the polluted water. Second, the phenol adsorption effects of UV synergistic biomass activated carbon, biomass activated carbon and ordinary industrial activated carbon under different influencing factors are compared by experiments. Finally, the results are analyzed and the conclusions are drawn. The results show that the UV synergistic biomass activated carbon has the strongest degradation ability for phenol, and the highest removal rate is 66.5% when the shaking time is 65 minutes. The adsorption ability of the industrial activated carbon for phenol is the worst. When the initial concentration of phenol is 25mg/L, the maximum phenol removal rate is 96.8%. The maximum phenol removal rate of biomass activa ted carbon appears in the initial concentration of phenol and the phenol removal rate is 60 mg/L. The reaction temperature has little effect on the phenol removal rate of UV synergistic biomass activated carbon and biomass activated carbon. The phenol removal ability of UV synergistic biomass activated carbon and biomass activated carbon reaches the highest when the dosage of activated carbon is 2.0 g, and the rates are 96.4% and 91.1%, respectively. When the pH of the solution is 7, the removal rate of UV synergistic biomass activated carbon reaches a maximum of 97%. When the pH of the solution is 6, the removal rate of biomass-activated carbon reaches the maximum. When the pH of the ordinary industrial activated carbon is 7, the removal rate is the maximum. Due to different influencing factors, UV synergistic biomass activated carbon has the strongest phenol degradation ability. This study provides a reference for the purification of polluted water.

Application of clayware ceramic separator modified with silica in microbial fuel cell for bioelectricity generation during rice mill wastewater treatment.

Ceramic separators have recently been investigated as low-cost, robust, and sustainable separators for application in microbial fuel cells (MFC). In the present study, an attempt was made to develop a low-cost MFC employing a clayware ceramic separator modified with silica. The properties of separators with varying silica content (10%-40% w/w) were evaluated in terms of oxygen and proton diffusion. The membrane containing 30% silica exhibited improved performance compared to the unmodified membrane. Two identical MFCs, fabricated using ceramic separators with 30% silica content (MFCS-30) and without silica (MFCC), were operated at hydraulic retention time of 12 h with real rice mill wastewater with a chemical oxygen demand (COD) of 3,200 ± 50 mg/L. The maximum volumetric power density of 791.72 mW/m3 and coulombic efficiency of 35.77% was obtained in MFCS-30, which was 60.4% and 48.5%, respectively, higher than that of MFCC. The maximum COD and phenol removal efficiency of 76.2% and 58.2%, respectively, were obtained in MFCS-30. MFC fabricated with modified ceramic separator demonstrated higher power generation and pollutant removal. The presence of hygroscopic silica in the ceramic separator improved its performance in terms of hydration properties and proton transport.

Modeling of phenol removal from water by NiFe2O4 nanocomposite using response surface methodology and artificial neural network techniques

This study demonstrates the synthesis, characterization, and modeling of nickel ferrite nanocomposite, NiFe2O4 (NFC) as an adsorbent for the phenol contaminated aqueous environment. The characterization of the prepared NFC was performed with X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) techniques. The optimization and modeling of phenol removal using NFC was done through central composite design (CCD) and effective parameters of CCD were measured as input variables including the amount of NFC, pH, contact time and initial phenol concentration. The predicted results showed that the adsorption process using NFC as adsorbent had the maximum phenol removal (~99%) under predicted optimal conditions (pH = 7.67, NFC dosage = 0.15 g at room temperature), which also corresponded to the experimental values. In addition, a multilayer feed-forward artificial neural network (ANN) model was used to obtain a speculative phenol removal model. The network was trained for six replications after selection of the best neuron number for hidden layer. The value of MSE trained network was found to be 6.01718e-3 along with regression coefficient (R2 = 0.9934) that indicated satisfactory relationship. Isothermal modeling of phenol adsorption onto NFC was performed using well-known Temkin, Freundlich and Langmuir models and it was clear from the higher R2 value of 0.961 that the Langmuir model was significantly followed by experimental data. The maximum Langmuir adsorption capacity was found to be 274.72 mg/g at the optimal conditions. The obtained results prove that NFC could be an effective adsorbent for elimination of phenol contaminant from aqueous environment.

Anaerobic mixed consortium (AMC) mediated enhanced biosynthesis of silver nano particles (AgNPs) and its application for the removal of phenol

In this research, silver nano particle (AgNP), was synthesized through a novel anaerobic mixed consortium mediation method and applied for the removal of phenol. The best operating conditions for the fabrication of silver nanoparticles were identified through response surface methodology (RSM) and the maximum yield was found to be 2.65 g/100 ml of anaerobic mixed consortium at optimal conditions of pH-8.6, temperature-90 °C, silver nitrate concentration-3 mg/ml and inoculum volume-3 ml. The synthesized nano particle exhibited a maximum phenol removal of 87.65% was achieved at pH:5.8. The synthesized silver nanoparticles were characterized by superior surface area (19.26 m2/g) and the stability was confirmed by thermo gravimetric analysis (upto 500 °C). The surface morphology was well explained using High Resolution Transmission Emission Microscopy (HR-TEM) and Scanning Electron Microscope with EDS (SEM-EDS) techniques. X-ray Diffraction (XRD) analysis confirmed the changes in crystalline structure due to the adsorption of phenol. Kinetic experiments fitted well with the intra-particle diffusion model. The nature of adsorption of phenol was confirmed as monolayer by the goodness of fit with Langmuir isotherm (R2 > 0.9969).

Development of MWCNTs/TiO2 nanoadsorbent for simultaneous removal of phenol and cyanide from refinery wastewater

The continuous discharge of untreated refinery wastewater containing pollutants into the water bodies have raised enormous concern on the safety of human, aquatic species and therefore calls for concerted efforts towards developing effective and sustainable treatment method. This study focused on the development of MWCNTs/TiO2 nanoadsorbent for the removal of phenol and cyanide from refinery wastewater. MWCNTs was prepared via cracking of acetylene gas on nickel ferrites nanoparticles in a long tubular reactor. The MWCNTs and MWCNTs/TiO2 nanoadsorbent were characterized for surface properties. HR-SEM and HR-TEM results revealed successive dispersion of TiO2 on the pores of MWCNTs with average crystallite size of 37.32 nm and surface area of 360.66 m2/g. The batch adsorption process revealed maximum removal of cyanide and phenol onto MWCNTs/TiO2 adsorbent at 70 min, 0.3 g and 40 °C contact time, adsorbent dosage and temperature respectively. The experimental data were better described by Freundlich Isotherm and Pseudo second order kinetic model, an indication of multilayer adsorption. The values of the free energy change, (ΔG) were negatives which suggested the existence of strong bond formation between the adsorbates and the adsorbents. The study demonstrated that the developed MWCNTs/TiO2nanoadsorbent is an excellent material for the sequestration of phenol and cyanide from refinery wastewater.

A holistic Fenton oxidation-biodegradation system for treatment of phenol from coke oven wastewater: Optimization, toxicity analysis and phylogenetic analysis

In this study, the efficacy of a hybrid treatment approach by integrating Fenton’s oxidation with biological treatment for removal of phenol from synthetic coke oven wastewater was investigated. Central composite design using response surface methodology was applied to optimize the dose of FeSO4 and H2O2 with maximum phenol removal and minimum toxicity. Results indicate that 6.3 mM and 20 mM of FeSO4 and H2O2 respectively, were capable of 74 % degradation of 1000 mg/L phenol, 99.99 % of 100 mg/L of cyanide with 10 % residual toxicity, which was acceptable for the next biological treatment step. On the basis of biodegradation studies it was found that a mixed consortium of three isolated bacterial strains namely BSPS_CN, BSPS_PHE and BSPS_PHE2 were capable of 98.8 % degradation of 300 mg/L phenol, which was remaining after the Fenton treatment. BSPS_PHE2 was found to be the most efficient with 92.45 % phenol removal efficiency. Phylogenetic analysis of cultures indicated that isolates BSPS_PHE and BSPS_PHE2 were genetically most closely related to Pseudomonas species, whereas BSPS_CN was found to be closely related to Enterobacter sp. The 2-step sequential treatment was capable of achieving 99.3 % degradation of 1000 mg/L phenol and complete removal of cyanide (100 mg/L) from coke oven wastewater. Harmonization of Fenton’s oxidation with biodegradation makes the treatment method more economical and was found to be an efficient method for removal of recalcitrant compounds from coke oven wastewater.

Hydrodynamics and phenol adsorption studies in continuous counter current liquid-solid settling column

Adsorption is a cost-efficient and a well-established method to treat a large volume of wastewater. Most of the adsorption studies have been carried out in batch and continuous (packed and fluidized bed column) reactors. In most of the continuous operations, a solid adsorbent is held in batch mode and the liquid phase is continuous. In a counter-current liquid-solid adsorber, both the liquid and solid phase will be continuous. In this study, synthetic wastewater containing phenol of 200 ppm is treated in a counter-current liquid-solid adsorber using activated carbon as the adsorbent. The adsorption kinetics and the effect of size and mass of adsorbent were studied in batch operation. Thermodynamic properties including Gibbs' free energy, standard enthalpy and entropy change were calculated and the feasibility of the process is confirmed. In the continuous counter-current liquid-solid settling column, the effects of liquid flow rate, particle size and solid flow rate on hydrodynamics and mass transfer have been studied. From the range of flow rates studied in this work, liquid flowrate of 10 lph and solids (of diameter 0.5 mm) flow rate of 24 g/s gave the maximum phenol removal. An empirical equation has been proposed to predict the mass transfer coefficient for the range of continuous process.

Collective removal of phenol and ammonia in a moving bed biofilm reactor using modified bio-carriers: Process optimization and kinetic study

The performance of a moving bed biofilm reactor (MBBR) with bio-carriers made of polypropylene-polyurethane foam (PP-PUF) was evaluated for the collective removal of phenol and ammonia. Three independent variables, including pH (5.0–8.0), retention time (2.0–12.0 h), and airflow rate (0.8–3.5 L/min) were optimized using central composite design (CCD) of response surface methodology (RSM). The maximum removal of phenol and ammonia was obtained to be 92.6, and 91.8%, respectively, in addition to the removal of 72.3% in the chemical oxygen demand (COD) level at optimum conditions. First-order and second-order kinetic models were analyzed to evaluate the pollutants removal kinetics in a MBBR. Finally, a second-order model was found to be appropriate for predicting reaction kinetics. The values of second-order rate constants were obtained to be 2.35, 0.25, and 1.85 L2/gVSS gCOD h for phenol, COD, and ammonia removal, respectively.