Synthetic Phenolic Wastewater Research Articles

Biodegradation of Phenol in Synthetic Wastewater Using a Fixed Bed Reactor With up Flow Sludge Blanket Filtration (FUSBF).

In the present study, the removal of phenol from synthetic wastewater was evaluated in a fixed bed reactor with up flow sludge blanket filtration (FUSBF) in comparison with a typical USBF system. At hydraulic retention time (HRT) of 24 hours and solid retention time (SRT) of 20 day, the effect of initial concentration of phenol (260-1020 mg/L) on phenol and chemical oxygen demand (COD) removal efficiency (%) was investigated in both systems. The effect of the presence of fixed bed was determined throughout the operational period.The results showed that the FUSBF system had a better ability than the typical USBF system in terms of phenol and COD removal. The average phenol and COD removal at phenol concentration of 312 mg/L was 97.52% and 92.82% for the FUSBF system and 92.80% and 82.18% for the typical USBF system, respectively. At HRT of 24 h and organic loading rate (OLR) of 30 g/m-3.h-1, the amount of phenol removal was 82.1%. At OLR of 30 g/m-3.h-1, role of fixed bed in phenol and COD removal was 25.01% and 29.3%, respectively, overall, the FUSBF system has a higher efficiency and ability than that of typical USBF and can be used for the purification of industrial wastewater containing refractory organic compounds such as phenol.

Application of Artificial Neural Networks for Prediction of Photocatalytic Reactor

In this paper, forecasting of kinetic constant and efficiency of photocatalytic process of TiO2 nano powder immobilized on light expanded clay aggregates (LECA) was investigated. Synthetic phenolic wastewater, which is toxic and not easily biodegradable, was selected as the pollutant. The efficiency of the process in various operation conditions, including initial phenol concentration, pH, TiO2 concentration, retention time, and UV lamp intensity, was then measured. The TiO2 nano powder was immobilized on LECA using slurry and sol-gel methods. Kinetics of photocatalytic reactions has been proposed to follow the Langmuir-Hinshelwood model in different initial phenol concentration and pH. Several steps of training and testing of the models were used to determine the appropriate architecture of the artificial neural network models (ANNs). The ANN-based models were found to provide an efficient and robust tool in predicting photocatalytic reactor efficiency and kinetic constant for treating phenolic compounds.

Primary sewage sludge-derived activated carbon: characterisation and application in wastewater treatment

The present study deals with the characterization of primary sewage sludge-derived activated carbons which were used for phenol adsorption from the synthetic wastewater. The waste-derived adsorbents were prepared by a two-step process: chemical activation (with ZnCl2 and KOH) followed by pyrolysis. The mesoporous adsorbents were found to have BET surface area comparable to commercial activated carbon (surface area = 495–515 m2/g). The adsorption runs were performed in orbital shaker with synthetic phenolic wastewater (phenol concentration = 50–250 mg/L) to investigate the effect of various reaction parameters. The equilibrium phenol adsorption data could be described by Redlich–Peterson isotherm model and the pseudo first-order kinetic model exhibited the best fit to time-based adsorption data. The phenol adsorption was endothermic for all adsorbents. The performance of the thermally regenerated waste-derived adsorbents in the wastewater treatment was found to reduce significantly.

Continuous multi-cell electrochemical reactor for pollutant oxidation

Degradation of organic pollutants using electrochemical method has obtained great attentions in recent years. Up to now, most works have focused on electrode property improving and pollutant degradation efficacy examining, but very few efforts have been paid to the electrochemical reactor investigation. This article presents a novel continuous multi-cell electrochemical reactor, which consists of ten serially connected cells using PbO2/Ti anode and stainless steel cathode with a short electrode gap of only 2mm. Hydraulic characteristics of the reactor were investigated using the residence time distribution (RTD) studies. The low dispersion number, 0.06, and Morrill dispersion index (MDI), 1.91, indicate that the reactor is close to a plug-flow reactor (PFR). Electrolysis of 50mg/L synthetic phenol wastewater was conducted using the multi-cell reactor at a current density of 10mA/cm2, a retention time of 100min and an electrolyte conductivity of 2.5mS/cm, and the chemical oxygen demand (COD) of the effluent was only 16mg/L. During the electrolysis process, the applied voltage in each cell kept stable at a low value of 3.4V. A comparison between the multi-cell reactor and the conventional single cell reactor for wastewater treatment under the same operating conditions showed that the multi-cell reactor performed much better than the single-cell reactor. For treating 500mg/L phenol wastewater, the effluent COD of the single-cell reactor was 534mg/L, with a current efficiency of only 19.9%. On the contrary, the effluent COD of the multi-cell reactor was 242mg/L and the current efficiency could reach 71.8%.

Phenolic wastewater treatment by an electrocatalytic membrane reactor

An electrocatalytic membrane reactor (ECMR) constituted by TiO2 loading carbon membrane named TiO2/carbon electrocatalytic membrane as an anode and a stainless steel mesh as a cathode has been employed to treat phenolic wastewater. A synthetic phenol wastewater as the feed was prepared by mixing phenol and electrolyte (Na2SO4) with the concentration of 15g/L. FESEM, XPS, cyclic voltammetry (CV) and high-performance liquid chromatography (HPLC) were used to characterize and analyze the electrocatalytic membrane, phenol concentration and degraded intermediates. The results showed that the removal rate of phenol and TOC reached approximately 99.4 and 86.3% after 2h treatment at 2.0mM phenolic wastewater by ECMR, respectively. The main intermediate products of phenol degradation included benzoquinone and organic acids. The efficiency and the degraded intermediates could be controlled by the main parameters of ECMR such as residence time, current density, etc. During the ECMR operation under the conditions of 10.0mM phenolic wastewater, pH of 6, current density of 0.3mA/cm2 and residence time of 5.2min, the achieved phenol removal rate and complete mineralization fraction were 99.96 and 72.4%, respectively. The high efficiency and phenol removal obtained are related to the synergistic effect of the electrochemical oxidation and separation in the reactor.

Extraction of peroxidase from waste Brassica oleracea used for the treatment of aqueous phenol in synthetic waste water

In this study, peroxidase was extracted from waste cauliflower stem and leaf and was partially purified. Peroxidase activity of cauliflower stem extract was found to be greater than that in leaf extract. Optimal temperature, pH and ionic strengths for cauliflower stem extract were found to be using pyrogallol/H2O2 substrate and used to catalyze the oxidation and polymerization of phenolic compounds in synthetic waste water. Further, the effect of H2O2, enzyme concentration, initial phenol and polyethylene glycol (PEG) concentrations was investigated on the phenol removal process. In the presence of PEG the phenol removal increased dramatically from 35% to >90% and FT-IR study on phenol samples before and after the peroxidase treatment showed the phenol radical formation and a decrease in phenol concentration.

Fabrication of catalytic membrane contactors based on polyoxometalates and polyvinylidene fluoride intended for degrading phenol in wastewater under mild conditions

A novel catalytic membrane contactor (CMC) has been designed and constructed by incorporating polyoxometalates (POMs) onto polymeric polyvinylidene fluoride (PVDF) micro-porous hollow fiber membranes which were fabricated by a dry–jet wet spinning process. A simple chemical deposition method was utilized to anchor the Keggin-type polyoxometalate H5[PV2Mo10O40] (PV2Mo10) on the outer surface of the PVDF hollow fiber, which was confirmed by the measurements of field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). The degradation of phenol in synthetic wastewater was carried out using air as green oxidant under room conditions using the CMC. A gas-catalyst-liquid interface was successfully built up to enhance the catalytic efficiency. It was observed that the pressure of the gas flow played an important role and a low pressure is preferable. The long-term stability of the CMC was also preliminarily studied. This novel and facile CMC with PV2Mo10 as catalyst potentially provides a feasible pathway for wastewater treatment under mild conditions.

Degradation of Organic Pollutants by Wet Air Oxidation Using Nonnoble Metal-Based Catalysts

AbstractPhenol is a major organic pollutant found in wastewater streams generating from several industries. The presence of excess phenol makes the wastewater unsuitable for conventional biological treatment. The present study was performed to treat synthetic phenolic wastewater by catalytic wet air oxidation (CWAO) at low operating conditions (90–150°C temperature and 0.5 MPa total air pressures). In addition, the degradation of two major intermediates (acetic acid and oxalic acid) was also observed under similar operating conditions. The reaction was performed in a stainless steel (SS-316) high-pressure reactor. Among all homogeneous (CuSO4 and FeSO4) and heterogeneous catalysts (CuO/CeO2 in different proportions: 100/0, 80/20, 60/40, and 50/50), CuSO4 exhibited the best performance with more than 90% reductions in phenol and total organic carbon (TOC) at 120°C temperature within 4 h. CuSO4 showed good capability for the removal of oxalic and acetic acids (TOC reductions were 81% and 67%, respectively)....

Enhancement of Photocatalytic Activity of ZnO/SiO2by Nanosized Pt for Photocatalytic Degradation of Phenol in Wastewater

ZnO- nanoparticles were synthesized by a sol-gel technique from and tetraethyl orthosilicate (TEOS). The synthesized samples were further modified by nanosized Pt from H2PtCl6solution through photoassisted deposition (PAD) and impregnation (Img) routes. The obtained samples were characterized by a series of techniques including X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, N2adsorption, extended X-ray absorption fine structure (EXAFS), and transmission electron microscopy (TEM). The photocatalytic activity of the Pt-ZnO/ was evaluated by photocatalytic degradation of phenol in synthetic wastewater under UV-irradiation. Results obtained revealed that the surface area and the photocatalytic activity of the prepared samples were increased in the order ZnO/ < PAD: Pt-ZnO/ < img: Pt-ZnO/. The surface area decreased from 480 to 460 and 450 m2/g, while the efficiency of the phenol degradation increased from 80 to 85 and 100%, with the ZnO/, Img: Pt-ZnO-, and PAD: Pt-ZnO- samples, respectively.

10.2478/s11814-009-0242-3

Anaerobic and aerobic biodegradation were integrated in an internal airlift loop reactor (IALR) by adding porous microbial carriers. In this bioreactor, aerobic activated sludge was suspended in the liquid bulk, while the anaerobic microbes were attached within the core of carriers. The integrated IALR was applied to the treatment of synthetic phenol wastewater. After 50 days’ acclimation according to co-substance strategy, the influent COD decreased from 3,700 mg/L to 400 mg/L (phenol removal rate was over 99%) with the residence time of 24 h. High performance could be achieved under the operation condition of superficial gas flow rate higher than 0.07 cm/s, temperature beyond 15°C and the microbial carrier volume fraction larger than 5%. Integration of anaerobic/aerobic biodegradation in IALR enhanced the synergetic effects between aerobic and anaerobic degradation; therefore, it has great potential in the treatment of phenol wastewater and other wastewater containing hard biodegradable organics.

Anaerobic treatment of phenolic wastewater: Effect of phosphorous limitation

Synthetic phenolic wastewater representing an industrial synthetic wastewater was supplemented with varying amount of phosphorous (P) and treated in upflow anaerobic sludge blanket (UASB) reactor. The variation of chemical oxygen demand COD:P from 300:1 to 300:0.1 did not influence the conversion of phenol COD to methane COD. The concentration of P in the influent was reduced from 2.5 to 0.25 mg/L respectively. However, on further reducing the COD:P in the feed from 300:0.1 to 300:0 the (i) CH4-COD decreased from 90 to 40%, and (ii) cell yield reduced to 25–50%. The average cell yield was 3.5%. Percent P in cells varied from 0.6 to 2.4% respectively. The activity of the sludge assessed as specific methanogenic activity (SMA) was found in the range of 0.15–0.66 g CH4-COD/g VSS d−1. The optimum COD: P for synthetic phenolic wastewater has been estimated to be 300:0.1.

Integrated anaerobic/aerobic biodegradation in an internal airlift loop reactor for phenol wastewater treatment

Anaerobic and aerobic biodegradation were integrated in an internal airlift loop reactor (IALR) by adding porous microbial carriers. In this bioreactor, aerobic activated sludge was suspended in the liquid bulk, while the anaerobic microbes were attached within the core of carriers. The integrated IALR was applied to the treatment of synthetic phenol wastewater. After 50 days’ acclimation according to co-substance strategy, the influent COD decreased from 3,700 mg/L to 400 mg/L (phenol removal rate was over 99%) with the residence time of 24 h. High performance could be achieved under the operation condition of superficial gas flow rate higher than 0.07 cm/s, temperature beyond 15°C and the microbial carrier volume fraction larger than 5%. Integration of anaerobic/aerobic biodegradation in IALR enhanced the synergetic effects between aerobic and anaerobic degradation; therefore, it has great potential in the treatment of phenol wastewater and other wastewater containing hard biodegradable organics.

CuO impregnated activated carbon for catalytic wet peroxide oxidation of phenol

This paper presents an original approach to the removal of phenol in synthetic wastewater by catalytic wet peroxide oxidation with copper binding activated carbon (CuAC) catalysts. The characteristics and oxidation performance of CuAC in the wet hydrogen peroxide catalytic oxidation of phenol were studied in a batch reactor at 80 °C. Complete conversion of the oxidant, hydrogen peroxide, was observed with CuAC catalyst in 20 min oxidation, and a highly efficient phenol removal and chemical oxygen demand (COD) abatement were achieved in the first 30 min. The good oxidation performance of CuAC catalyst was contributed to the activity enhancement of copper oxide, which was binding in the carbon matrix. It can be concluded that the efficiency of oxidation dominated by the residual H 2O 2 in this study. An over 90% COD removal was achieved by using the multiple-step addition in this catalytic oxidation.

Electrochemical catalytic treatment of phenol wastewater

The slurry bed catalytic treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. In this paper, the electrochemical oxidation of phenol in synthetic wastewater catalyzed by ferric sulfate and potassium permanganate adsorbed onto active bentonite in slurry bed electrolytic reactor with graphite electrode has been investigated. In order to determine the optimum operating condition, the orthogonal experiments were devised and the results revealed that the system of ferric sulfate, potassium permanganate and active bentonite showed a high catalytic efficiency on the process of electrochemical oxidation phenol in initial pH 5. When the initial concentration of phenol was 0.52 g/L (the initial COD 1214 mg/L), up to 99% chemical oxygen demand (COD) removal was obtained in 40 min. According to the experimental results, a possible mechanism of catalytic degradation of phenol was proposed. Environmental estimation was also done and the results showed that the treated wastewater have little impact on plant growth and could totally be applied to irrigation.

Combined effect of plate pulsation parameters and phenol concentrations on the phenol removal efficiency of a pulsed plate bioreactor with immobilized cells

Continuous aerobic biodegradation of phenol in synthetic wastewater with phenol at different concentrations (200, 300, 500, 800 and 900 ppm) was carried out in a pulsed plate column, which is used as a bioreactor with immobilised cells of Nocardia hydrocarbonoxydans (NCIM 2386) at a dilution rate of 0.4094 h(-1) and amplitude of 4.7 cm at various frequencies of pulsation (0, 0.25, 0.5, 0.75 and 1 s(-1)). The effect of frequency of pulsation on the steady state performance of the bioreactor for phenol biodegradation at different influent concentrations was studied. Percentage degradations were observed to be a combined effect of volumetric phenol loading, reactor residence time, mass transfer limitations and phenol inhibition effect. At 500 ppm influent phenol concentration the effect of frequencies of pulsation on the steady state percentage degradation at different amplitudes was studied. The percentage degradation increased with increase in frequency and almost 100% degradation was achieved at 0.75 s(-1), 0.5 s(-1) or 0.25 s(-1), with 3.3, 4.7 or 6.0 cm amplitudes respectively and hence the vibrational velocity (amplitude*frequency) was found to influence the steady state performance of the reactor. It was found that optimum vibrational velocities need to be fixed for maximum removal efficiency of the bioreactor depending on the influent phenol concentration.

Abatement of the Inhibitory Effect of Chloride Anions on the Photo-Fenton Process

The inhibition of the photo-Fenton (Fe2+/Fe3+, H2O2, UV light) degradation of synthetic phenol wastewater solutions by chloride ions is shown to affect primarily the photochemical step of the process, having only a slight effect on the thermal or Fenton step. Kinetic studies of the reactions of oxoiron (IV) (FeO2+) with phenol indicate that, if FeO2+ is formed in the photo-Fenton degradation, its role is probably minor. Finally, it is shown that, for both a synthetic phenol wastewater and an aqueous extract of Brazilian gasoline, the inhibition of the photo-Fenton degradation of the organic material in the presence of chloride ion can be circumvented by maintaining the pH of the medium at or slightly above 3 throughout the process, even in the presence of significant amounts of added chloride ion (0.5 M).

Micellar enhanced ultrafiltration of phenol in synthetic wastewater using polysulfone spiral membrane

The micellar enhanced ultrafiltration (MEUF) of phenol in synthetic wastewater using two polysulfone spiral membranes of 6- and 10-kDa molecule weight cut-off (MWCO) and cetylpyridinium chloride (CPC) as cationic surfactant was studied. The effects on the permeate flux, permeate and retentate concentrations of phenol and CPC of various factors in the practical application of MEUF were studied, including surfactant and phenol concentrations, retentate flux, operating pressure, temperature and electrolyte. It was found that these two membranes could adsorb free phenol so the concentration of permeate phenol was lower than that of free phenol. The retentate phenol concentration kept increasing, then decreased slightly with the increase of the feed CPC concentration. Retentate flux and temperature had great effect on the performance of MEUF, and operating pressure did not. The addition of sodium carbonate (Na 2CO 3) could increase the retentate phenol concentration and decrease the permeate concentrations of phenol and CPC significantly.

Biological phenol removal using immobilized cells in a pulsed plate bioreactor: Effect of dilution rate and influent phenol concentration

The continuous aerobic biodegradation of phenol in synthetic wastewater was carried out using Nocardia hydrocarbonoxydans immobilized over glass beads packed between the plates in a pulsed plate bioreactor at a frequency of pulsation of 0.5 s −1 and amplitude of 4.7 cm. The influence of dilution rate and influent phenol concentration on start up and steady state performance of the bioreactor was studied. The time taken to reach steady state has increased with increase in dilution rate and influent phenol concentration. It was found that, as the dilution rate is increased, the percentage degradation has decreased. Steady state percentage degradation was also reduced with increased influent phenol concentration. Almost 100% degradation of 300 and 500 ppm influent phenol could be achieved at a dilution rate of 0.4094 h −1 and more than 99% degradation could be achieved with higher dilution rates. At a higher dilution rate of 1.0235 h −1 and at concentrations of 800 and 900 ppm the percentage degradation has reduced to around 94% and 93%, respectively. The attached biomass dry weight, biofilm thickness and biofilm density at steady state were influenced by influent phenol concentration and dilution rate.

Evaluation of sequencing batch reactor performance with aerated and unaerated FILL periods in treating phenol-containing wastewater

Performance of the sequencing batch reactor (SBR) treating synthetic phenolic wastewater at influent phenol concentrations from 100 to 1000 mg/L was evaluated. Two identical SBRs were built and operated with FILL, REACT, SETTLE and DRAW periods in the ratio of 4:6:1:1 for a cycle time of 12 h. One of the reactors was operated with aerated FILL (R1) and the other with unaerated FILL (R2). The treated effluent quality and the rate of degradation during REACT were the criteria for evaluating performance of the two reactors. The results showed that the FILL mode had no significant influence on the treatment efficiency of phenol and COD for the entire range of influent phenol concentrations investigated. However, reactor R1 required a relatively shorter REACT time for phenol removal as compared to R2. This meant that R1 had the advantage of providing treatment at a higher organic loading rate.

Electrochemical catalytic treatment of wastewater by metal ion supported on cation exchange resin

The electrochemical oxidation of phenol in synthetic wastewater and paper mill wastewater catalyzed by metal ion supported on cation exchange resin in suspended bed electrolytic reactor with graphite electrode has been investigated. The catalyst was characterized by SEM and XPS spectra and the effects of pH, the different metal ion and NaCl on the efficiency of the electrochemical oxidation phenol process were also studied. It was found that the catalyst containing Fe 3+ had the highest electrochemical catalytic activity for the electrochemical oxidation of phenol. When the initial concentration of phenol was 200 ppm, up to 90% chemical oxygen demand (COD) removal was obtained in 10 min. When the catalyst containing Fe 3+ was used to the paper mill wastewater, it still showed high efficiency. The COD removal could get to 75% in 60 min.