Treatment Of Petroleum Refinery Wastewater Research Articles

Treatment of vegetable oil refinery wastewater using alumina ceramic membrane: optimization using response surface methodology

New regulations in environment protection and increasing market demands for “green” companies are forcing the industry to consider finding new and sustainable methods of wastewater treatment. The valuable information regarding treatment of the wastewater from the edible oil industry is presented in this research. The obtained results confirm a promising application of the third generation membranes, comprised of ceramic material (aluminium oxide), in treatment of wastewater from the edible oil industry. Positive results regarding chemical oxygen demand reduction and turbidity removal were noticed. Permeate flux values were used for process optimization in order to achieve a cost-effective process. Response surface methodology was used for the experimental design. The effects of wastewater temperature, transmembrane pressure, and feed-flow rate on the microfiltration model fit were studied. The experiments showed that microfiltration of this type of wastewater is a convenient technique for a possible large scale industrial application as a secondary step in treating wastewater from the oilseed processing facilities.

Oil Refinery Wastewater Treatment by Using Membrane Bioreactor (MBR)

In this work, a new hollow fiber membrane was fabricated for the treatment of industrial wastewater in Al-Daura refinery in Baghdad using the submerged membrane bioreactor (MBR) technique with a new membrane-type module. The hollow fiber characterization seems to be within the range of ultrafiltration membranes, and the fabricated hollow fibers have a skinless porous outer surface. The effects of mixed liquor suspended solids (MLSS) concentration (i.e., 500 and 1000 mg/l) and preheating temperatures of the effluent wastewater (i.e., 25, 45, and 55 °C) at different preheating periods (i.e., 15, 30, and 45 min) on the performance of MBR and removal efficiency of COD, BOD, oil content, phenol, and turbidity were investigated. It was found that the removal efficiency of COD, BOD, oil content, phenol, and turbidity were enhanced by increasing of MLSS concentration. This efficiency was significantly enlarged by applying different preheating temperatures and times. For example, at 45 min preheating time, the removal efficiency of COD, BOD, oil content, and phenol at 1000 mg/l, and 55 °C were measured to be 71, 60 and 100 %, respectively. In fact, the obtained results confirmed that the initial wastewater preheating followed by the submerged MBR can be offered a possibility of alternative process for oily wastewater treatment, especially when reuse of oily wastewater is taken into account.

Toxicity and biogas production potential of refinery waste sludge for anaerobic digestion

Two waste streams from an oil refinery wastewater treatment system, float from a dissolved air flotation unit (DAF sludge) and waste activated sludge (WAS), were investigated to determine toxicity and biogas production potential for anaerobic digestion through batch testing methods. Ozonation as a pretreatment was investigated to observe the impacts of waste solubilization on both toxicity and biodegradability. Anaerobic toxicity assays resulted in no detectible inhibition from WAS, neither with nor without ozonation. Untreated DAF sludge exhibited inhibition that amplified with the increases in DAF sludge inclusion. Ozone treatment effectively reduces this inhibition. The biodegradability of WAS, measured by biochemical methane potential tests, doubled with low dose ozonation. DAF sludge biodegradability was negligible prior to treatment and was successfully enhanced through ozonation.

A real petroleum refinery wastewater treatment using hollow fiber membrane bioreactor (HF-MBR)

In this paper, the capability of hollow-fiber membrane bioreactor (HF-MBR) for real petroleum refinery wastewater treatment was studied. A pilot immersed HF-MBR was designed, and the treatment investigated under various hydraulic retention time (HRT), flux, temperature, and different operational conditions. The bioreactor included an ultrafiltration membrane (UF) and Arak refinery wastewater used as the influent stream. The HF-MBR was running throughout 160 days. The result indicated that average elimination efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD5), total suspended solids (TSS), volatile suspended solids (VSS) and turbidity were attained 82%, 89%, 98%, 99%, and 98%, respectively. Furthermore, the mixed liquor-suspended solid (MLSS) and mixed liquor volatile-suspended solids (MLVSS) concentration raised from minimal concentration to about 6.6 and 6.1g/L, respectively.

An alternative anaerobic treatment process for treatment of heavy oil refinery wastewater containing polar organics

Heavy oil is an important part of energy sources, but the refining wastewater is difficult to treat by the conventional anaerobic process, which has low efficiency and poor ability to resist impact load. In this study, an up-flow anaerobic sludge bed (UASB) reactor was applied to treat heavy oil refinery wastewater containing large amounts of polar organics. Through a progressive increase of hydraulic conditions, the average removal efficiencies of COD and total oil reached 70% and 72%, respectively, at an organic loading rate (OLR) of 3.44kg COD/m3d. GC–MS analysis revealed that more biodegradable organic acids and alcohols were generated and macromolecular polar organics were degraded into small molecular intermediates after UASB treatment. The morphology observation of the sludge demonstrated that granular sludge with an average particle size of 1mm was formed. Moreover, the predominant species and microbial community shift could reflect the performance of the reactor. The long-term operation of UASB exhibited excellent polar organic removal efficiency. The study demonstrated the potential of UASB as an alternative for high-efficiency anaerobic treatment of heavy oil refinery wastewater.

Preparation of multi-walled carbon nanotube-doped TiO2 composite and its application in petroleum refinery wastewater treatment

Electron–hole recombination is the most important factor limiting the efficiency of TiO2-based photocatalysts. In this work, multi-walled carbon nanotube (MWCNT) was used to suppress the electron–hole recombination and enhance the photocatalytic efficiency of titanium dioxide (TiO2) nanoparticles. Primarily, nanocomposite of MWCNT/TiO2 as a hybrid photocatalyst with different weight ratio of TiO2 and MWCNT (from 0.95:0.05 to 0.75:0.25) was produced and characterized. The composites were characterized by a series of analytical techniques including SEM, TEM, XRD, and UV–vis to reveal the textural, crystallographic, and optical properties of the composites. These techniques indicated a uniform, mesoporous, and well-defined nanometer scale anatase titania (TiO2) layer on individual MWCNT. Secondly, significantly enhanced photocatalytic activity of TiO2 was systematically studied by introducing MWCNT in the photocatalytic oxidation and mineralization of petroleum refinery wastewater (PRW) in a batch circulating photocatalytic reactor. The results showed that when the proportion ratio of TiO2 and MWCNT reached 0.8:0.2, the synthesized MWCNT/TiO2 nanocomposite demonstrated the maximum photocatalytic efficiency on PRW treatment. The increase in the removal efficiency with increase in MWCNT/TiO2 ratio was due to great capability of MWCNT in the adsorption of organic molecules and charge separation.

Occurrences and behaviors of naphthenic acids in a petroleum refinery wastewater treatment plant.

Naphthenic acids (NAs) are one class of compounds in wastewaters from petroleum industries that are known to cause toxic effects, and their removal from oilfield wastewater is an important challenge for remediation of large volumes of petrochemical effluents. The present study investigated occurrences and behaviors of total NAs and aromatic NAs in a refinery wastewater treatment plant, located in north China, which combined physicochemical and biological processes. Concentrations of total NAs were semiquantified to be 113-392 μg/L in wastewater from all the treatment units, and the percentages of aromatic NAs in total NAs was estimated to be 2.1-8.8%. The mass reduction for total NAs and aromatic NAs was 15±16% and 7.5±24% after the physicochemical treatment, respectively. Great mass reduction (total NAs: 65±11%, aromatic NAs: 86±5%) was observed in the biological treatment units, and antiestrogenic activities observed in wastewater from physicochemical treatment units disappeared in the effluent of the activated sludge system. The distributions of mass fractions of NAs demonstrated that biodegradation via activated sludge was the major mechanism for removing alicyclic NAs, aromatic NAs, and related toxicities in the plant, and the polycyclic NA congener classes were relatively recalcitrant to biodegradation, which is a complete contrast to the preferential adsorption of NAs with higher cyclicity (low Z value). Removal efficiencies of total NAs were 73±17% in summer, which were higher than those in winter (53±15%), and the seasonal variation was possibly due to the relatively high microbial biotransformation activities in the activated sludge system in summer (indexed by O3-NAs/NAs). The results of the investigations indicated that biotransformation of NA mixtures by the activated sludge system were largely affected by temperature, and employing an efficient adsorbent together with biodegradation processes would help cost-effectively remove NAs in petroleum effluents.

Numerical Analysis of Petroleum Refinery Wastewater Treatment Using Electro-Fenton Process

Abstract The important parameters in mineralization treatment of petroleum refinery wastewater by electro-Fenton process were successfully simulated by Computational Fluid Dynamics (CFD). The effects of H2O2/PRW (ratio of mole of H2O2 per petroleum refinery wastewater volume), H2O2/Fe2+ molar ratio, current density, pH and reaction time were numerically investigated. Materials distribution in the electrochemical cell was studied and CFD results demonstrated that distance between electrodes had no significant effect on the Chemical oxygen demand (COD) removal. Furthermore, the results were compared with the experimental data. The simulated data showed that maximum COD removal was around 82.55% at H2O2/PRW of 0.04, H2O2/Fe2+ molar ratio of 2.75, pH of 3.5, current density of 52.5 mA/cm2 and reaction time of 90 min while the experimental data obtained from the literature showed maximum COD removal of 77% in the same operating conditions. The simulated data showed a good agreement with the experimental ones.

Treatment of petroleum refinery wastewater containing heavily polluting substances in an aerobic submerged fixed-bed reactor

Petroleum refineries produce large amount of wastewaters, which often contain a wide range of different compounds. Some of these constituents may be recalcitrant and therefore difficult to be treated biologically. This study evaluated the capability of an aerobic submerged fixed-bed reactor (ASFBR) containing a corrugated PVC support material for biofilm attachment to treat a complex and high-strength organic wastewater coming from a petroleum refinery. The reactor operation was divided into five experimental runs which lasted more than 250 days. During the reactor operation, the applied volumetric organic load was varied within the range of 0.5–2.4 kgCOD.m−3.d−1. Despite the inherent fluctuations on the characteristics of the complex wastewater and the slight decrease in the reactor performance when the influent organic load was increased, the ASFBR showed good stability and allowed to reach chemical oxygen demand, dissolved organic carbon and total suspended solids removals up to 91%, 90% and 92%, respectively. Appreciable ammonium removal was obtained (around 90%). Some challenging aspects of reactor operation such as biofilm quantification and important biofilm constituents (e.g. polysaccharides (PS) and proteins (PT)) were also addressed in this work. Average PS/volatile attached solids (VAS) and PT/VAS ratios were around 6% and 50%, respectively. The support material promoted biofilm attachment without appreciable loss of solids and allowed long-term operation without clogging. Microscopic observations of the microbial community revealed great diversity of higher organisms, such as protozoa and rotifers, suggesting that toxic compounds found in the wastewater were possibly removed in the biofilm.

Design and performance study of hybrid photocatalytic reactor-PVDF/MWCNT nanocomposite membrane system for treatment of petroleum refinery wastewater

This study focuses on the design and performance of a hybrid system consisting of a photocatalytic reactor and a membrane permeation cell. Initially, an ultraviolet lamp was installed in the photocatalytic reactor to decompose the organic pollutants in the presence of 200ppm titanium-dioxide (TiO2). Individual hydrocarbon pollutants were identified by gas chromatography–mass spectrometry (GC–MS) analysis of wastewater samples. Polyvinylidene fluoride (PVDF)/multi-walled carbon nanotube (MWCNT) nanocomposite membranes were fabricated to enhance the rejection, flux and fouling resistance for full filtration of pollutants from photocatalytic reactor such as decomposed refinery wastewater and TiO2 photocatalyst. The nanocomposite membranes were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TiO2 cross-over during permeation was detected by using an atomic adsorption spectrometer, which proved that TiO2 rejection was more than 99% for oxidized MWCNT nanocomposite membranes. Furthermore, GC–MS analysis was concluded over 90% decomposition which occurred by photocatalytic reaction and practically all pollutants were removed by ultrafiltration permeation cell. The nanocomposite membrane with 1.0wt.% of oxidized MWCNTs incorporated in PVDF matrix was found to be the best nanocomposite membrane among all of the fabricated membranes for the filtration purposes, due to the over 99% rejection and excellent anti-fouling property.

Treatment of vegetable oil refinery wastewater by sorption of oil and grease onto regranulated cork – A study in batch and continuous mode

The feasibility of a novel sorption treatment using regranulated cork granules for oil and grease (O&G) removal from real vegetable oil refinery wastewaters (VORW) was investigated and compared to similar treatment of oil-in-water emulsions.O&G sorption from real VORW onto regranulated cork particles was studied at different pH and ionic strength conditions. Only wastewater acidification was able to effectively destabilize the O&G emulsion in the wastewater, enhancing the sorption process (efficiency over 80% at pH 2.0).A 3-factor, 3-level (33) Box–Behnken experimental design was used to examine the effect of pH, ionic strength and soap/oil ratio on O&G removal efficiency in oil-in-water emulsions. All effects were significant (p<0.05) when considered individually, but no significant interactions were observed. pH was found to have the strongest effect, supporting the initial observations in real VORW.The treatment of a simulated wastewater (60% soap/oil ratio, 0.2M NaCl and pH 2.0) was completed in batch and continuous mode. Freundlich and linear partitioning models were used to describe O&G sorption equilibria. Continuous treatment was successfully carried out in a stirred-tank reactor using a cork dosage of 3.4gL−1, a stirring speed of 250rpm and a flowrate of 10mLmin−1. The reactor was fed for 8h with simulated wastewater (205±30mgL−1 O&G) yielding an effluent with an O&G content below 15mgL−1 (discharge limit defined in Portuguese legislation). A mass transfer model was applied to describe the O&G sorption kinetics in batch and continuous stirred-tank reactors.

Fenton oxidative treatment of petroleum refinery wastewater: process optimization and sludge characterization

Good sedimentation and compaction properties of the Fenton generated sludge shows its easy handling.

Treatment of the petroleum refinery wastewater using combined electrochemical methods

This study explores the performance of electrochemical and combined oxidation methods for the treatment of petroleum refinery wastewater (PRW). The electrocoagulation operating parameters studied includes reaction time and applied voltage. In situ hydrogen peroxide treatments at different dosages and hybrid electrochemical systems (ECEO, ECS25, ECS33, ECEO + US33) have been studied. The efficacy of the treatment system has been evaluated in terms of reduction of phenols, COD, TOC, oil, and grease. The most effective method for PRW treatment is ECEO + US33 where the maximum % removal of phenols, TOC, COD, oil, and grease are reported to be 98, 92, 92, and 92%, respectively. The results demonstrate the technical feasibility of using hybrid electrochemical process as a possible and reliable methods for the treatment of PRW.

Treatment of Petroleum Refinery Wastewater Using Extended Aeration Activated Sludge

The petroleum refinery wastewater biological treatment is widely investigated because of the potential complete mineralization and environmental aspect. In this study, petroleum refinery wastewater was treated in an extended aeration activated sludge (EAAS) reactor A, operated in parallel with EAAS reactor B as a control, fed with municipal wastewater. The chemical oxygen demand (COD) organic loading rate (OLR) of the refinery wastewater in reactor B was approximately 0.057 kg COD/m3·d compared to reactor A of 0.004 kg COD/m3·d throughout the study period. The flowrate for both reactors was maintained at 21.4 L/day. Food to microorganism (F/M) ratio, COD, mixed liquor suspended solids (MLSS), and mixed liquor volatile suspended solids (MLVSS) were monitored throughout the study period. The result indicated high removal efficiency of organic matter of approximately 87% as COD with 2582 mg/L of the petroleum refinery wastewater as influent and 140 mg/L as effluent.

A combination of solvent extraction and freeze thaw for oil recovery from petroleum refinery wastewater treatment pond sludge

A combination of solvent extraction and freeze thaw was examined for recovering oil from the high-moisture petroleum refinery wastewater treatment pond sludge. Five solvents including cyclohexane (CHX), dichloromethane (DCM), methyl ethyl ketone (MEK), ethyl acetate (EA), and 2-propanol (2-Pro) were examined. It was found that these solvents except 2-Pro showed a promising oil recovery rate of about 40%, but the recycling of DCM solvent after oil extraction was quite low. Three solvents (CHX, MEK and EA) were then selected for examining the effect of freeze/thaw treatment on improving the quality of recovered oil. This treatment increased the total petroleum hydrocarbon (TPH) content in recovered oil from about 40% to 60% for both MEK and EA extractions, but little effect was observed for CHX extraction. Although the solid residue after oil recovery had a significantly decreased TPH content, a high concentration of heavy metals was observed, indicating that this residue may require proper management. In general, the combination of solvent extraction with freeze/thaw is effective for high-moisture oily hazardous waste treatment.

Hybrid of Fenton and sequencing batch reactor for petroleum refinery wastewater treatment

The treatment of high-strength petroleum refinery effluent (PRE) with [BOD5]/[COD]0=0.14 was investigated using combined Fenton–sequencing batch reactor (SBR). The effect of [H2O2]:[COD]0 molar ratio on biodegradability enhancement was investigated. Fenton optimal conditions were: [H2O2]:[COD]0 of 6, [H2O2]:[Fe0] of 10 and pH=3.0 that could remove 76.5%, 45% and 96% of COD, TOC and phenol and increased biodegradability ratio to 0.37. The pretreated PRE subjected to SBR for one single cycle of 10h. The results revealed the effectiveness of hybrid Fenton–SBR system in treating PRE where the complete treatment of the PRE was attained by this system.

Prediction model development for petroleum refinery wastewater treatment

Multi-stage biological treatment of petroleum refinery wastewater using different biological conditions (anaerobic–anoxic–aerobic) has many advantages over other biological methods. It can result in maximum treatment for type of complex wastewater. In this study, raw data obtained from two multi-stage biological reactors (MSBR) used for treatment of different loads of petroleum refinery wastewater was used for developing mathematical model that could predict the process trend. The data consists of 160 entries and were gathered over approximately 180 days from two MSBR reactors that were continuously operated in parallel. A Matlab code was written with two configurations of artificial neural network. The configurations were compared and different number of neurons at the hidden layer were tested for optimum model that represent the process behavior under different loads. The tangent sigmoid transfer function (Tansig) at hidden layer and a linear transfer function (Purelin) at output layer with 6 neurons were selected as the optimum best model. The model was then used for prediction; highest removal efficiency observed was 98% which was repeatedly recorded for various loads. Effluent concentration below 100mg/L as chemical oxygen demand (COD) was recorded for influent concentration ranged between 900 and 3600mg COD/L.

Process modeling and evaluation of petroleum refinery wastewater treatment through response surface methodology and artificial neural network in a photocatalytic reactor using poly ethyleneimine (PEI)/titania (TiO2) multilayer film on quartz tube

In this study, poly ethyleneimine (PEI)/Titania (TiO2) multilayer film on quartz tubes have been successfully fabricated via a layer-by-layer (LbL) self-assembly method. Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area analysis were carried out for characterization of the layers on quartz tube. The SEM pictures showed that the film surface is smooth and uniform. The BET characterization verified the formation of multilayer thin film. The photocatalytic activity of the PEI/TiO2 multilayer deposited on the quartz tubes was evaluated in the treatment of raw petroleum refinery wastewater (PRW) under UV light irradiation in three annular photocatalytic reactors. This study examined the impact of initial chemical oxygen demand (COD) concentration, H2O2 concentration, pH and reaction time on the PRW treatment and the results were used to generate both a response surface methodology (RSM) model and an artificial neural network (ANN) model. Maximum COD removal (98 %) was achieved at the optimum conditions (initial COD concentration of 300 mg/l, hydrogen peroxide concentration of 8.8 mM, pH of 5 and reaction time of 120 min). A comparison between the model results and experimental data gave a high correlation coefficient (R ANN 2 = 0.9632, R RSM 2 = 0.943) and showed that two models were able to predict COD removal from PRW by PEI/TiO2/UV process. However, ANN model was superior to RSM model with higher value of coefficient of determination (0.9632ANN > 0.94RSM) and the lower root mean square error (RMSE) (3.377AAN < 3.569RSM). The average percentage error for ANN and RSM models was 0.18 and 0.73, respectively, indicating the superiority of ANN in capturing the nonlinear behavior of the system. It was clear that the best networks were able to predict the experimental responses more accurately than the multiple regression analysis.

Aerobic degradation of petroleum refinery wastewater in sequential batch reactor

The aim of the present work was to study the effect of various parameters affecting the treatment of raw petroleum refinery wastewater (PRW) having chemical oxygen demand (COD) of 350 mg L−1 and total organic carbon (TOC) of 70 mg L−1 in sequential batch reactor (SBR). Effect of hydraulic retention time (HRT) was studied in instantaneous fill condition. Maximum COD and TOC removal efficiencies were found to be 80% and 84%, respectively, for fill phase of 2 h and react phase of 2 h with fraction of SBR being filled with raw PRW in each cycle being 0.4. Effect of parameters was studied in terms of settling characteristic of treated slurry. Kinetics of treatment process has been studied. FTIR and UV-visible analysis of PRW before and after treatment have been performed so as to understand the degradation mechanism.

Preparation of poly ethyleneimine (PEI))/nano titania (TiO2) multilayer film on quartz tube by layer-by-layer self-assembly and its applications for petroleum refinery wastewater treatment

Poly ethyleneimine (PEI)/titania (TiO2) multilayer film on quartz tubes have been successfully fabricated via a layer-by-layer (LbL) self-assembly method. scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) surface area analysis were carried out for characterization and determination of the morphology and roughness of the prepared thin films on quartz tube. AFM and SEM images indicated that the film surface is smooth and uniform, and thickness of the film was estimated to be around 120nm. The BET characterization proved the formation of multilayer thin film. The photocatalytic activity of the PEI/TiO2 multilayer deposited on the quartz tubes was evaluated in the treatment of raw petroleum refinery wastewater (PRW) under UV light irradiation in three annular photocatalytic reactors. Our preliminary study showed that the most significant variables on the PRW treatment in these photoreactores are initial chemical oxygen demand (COD) concentration, H2O2 concentration, pH and reaction time. Thus, further experiments and optimization were performed using response surface methodology (RSM) based on three-level central composite design to evaluate process conditions. Maximum COD removal (98%) was achieved at the optimum conditions (initial COD concentration of 200mg/L, Hydrogen peroxide concentration of 8.8mM, pH of 6 and reaction time of 120min).