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The present study aims to investigate the feasibility of implementing the electrocoagulation (EC) process to treat Algiers refinery effluent. The electrocoagulation was performed by using scrap aluminum plate electrodes in monopolar-parallel mode. Several parameters, namely current density, reaction time, the electrolyte dose, and the initial chemical oxygen demand (COD) concentration were studied. The maximum removal of COD achieved was found to be 78.55%. Operating conditions at which maximum COD removal efficiencies were achieved at current density 8 mA/cm2, electrolyte dose 1 g/L, with 360 mg/L of initial COD concentration at working time of 40 min. An artificial neural network (ANN) was also utilized to determine predicted responses using neural networks for the 4-10-1 arrangement. The responses predicted by ANN were in alignment with the experimental results. The values of the determination coefficient (R2 = 0.978) and the root mean square error (RMSE = 21.28) showed good prediction results between the model and experimental data. Hence, the ANN model as a predictive tool has a great capacity to estimate the effect of operational parameters on the electrocoagulation process. HIGHLIGHTS Electrocoagulation treatment of petroleum refinery wastewater using Al electrode to remove COD, turbidity, and TSS.; Treated effluent concentration after EC treatment met standards discharge Algeria.; The ANN-based statistical model indicates the well-fitting and viability of the process.; Lower energy consumption depicts EC as a cheap (0.383 US$m−3) and accessible technology to treat petroleum refinery wastewater.;

The present work investigated the electrochemical performance of a 3D-printed lab-scale electrochemical cell frame doped with turbulent cylindrical promoters at the inlet using as a case study the treatment of Algiers refinery effluent. Residence time distribution (RTD) experiments were conducted to characterize the flow developed in the reaction environment. A kinetic study of chemical oxygen demand removal of the effluent was aimed to access the reaction rates. Results indicated that the experimental data from RTD fitted well the axially dispersed plug flow (AD-PFR) model with semi-infinite boundary conditions, whereas the kinetic response showed an agreement with a pseudo-first-order model. The mean residence time, the Peclet number (Pe) and the axial dispersion were estimated at 2.07s, 8.36 and 0.0012 m2/s, respectively. Interestingly, the results revealed a high dispersion for relatively low Reynolds number (Re) in the channel. This reflected the applicability of the proposed inlet design to treat low-loaded feeds at higher currents. Finally, the species residence time and the drag forces interaction on the electrode passivation was discussed and future implementation of the proposed inlet design was emphasized. [ABSTRACT FROM AUTHOR]

A synthetic wastewater based on Algiers refinery real effluent was prepared and treated using anodic oxidation. Full factorial plan design was used to conduct the statistical analysis of the results. The aim of the study was to assess the interaction between current density (CD) and stirring degree (SD), and quantify their effects on chemical oxygen demand (COD) removal and electric energy specific consumption (EESC). With an initial COD of 487 mg/L, pH of 5.5 and 0.05 M of Na2SO4 as supporting electrolyte, it was found that a 55 rpm stirring degree variation led to a substantial gain in COD removal and energy consumption: 6% and 8.5 KWh/kg, respectively. Current density was found to have a different effect on removal efficiency within the applied stirring domain, and mass transport coefficient (km) is inversely correlated to energy consumption. A theoretical model describing the process was reviewed and the relation between concentration, hydrodynamics and applied current was emphasized. HIGHLIGHTS A simple empirical modeling to assess charge rate and mass transport rate balance (i.e. operating regime).; Lead anode was first applied for electro-oxidation of toluene.; Perspectives on the up-scaling approach taken and comparative data were discussed.; Theoretical modeling review.;

Objectives:This comparative study investigated various methods of advanced oxidation processes (AOPs) that were separately conducted for treating raw petroleum refinery effluent regarding chemical oxygen demand (COD) removal. Methods:Fenton, photo-Fenton, TiO2, ZnO, TiO2/Ultra violet (UV), and ZnO/UV were performed individually for measuring the effect of light irradiation, treatment time, pH, catalysts dosage, and light source on the profile of COD values. Results and Discussion:The experimental data of this work showed that the dependency on the light exposure in heterogeneous photo-catalytic reaction using TiO2 and ZnO is higher than that of homogeneous photo-Fenton technique. The optimum operating conditions in heterogeneous system occurred at 100 min of oxidation time, pH 5, and catalyst dosage 1 g/L that resulted in 21.8, 20.68, 60.9, and 55.17% of COD removal for TiO2, ZnO, TiO2/UV, and ZnO/UV, respectively. In contrast, both Fenton and photo-Fenton experienced their highest performance at pH 4 by obtaining 44.2 and 59.77% of COD removal, respectively. Eventually, kinetic study indicated that COD degradation can be well expressed by second-order pattern that reached higher correlation coefficient values by 0.999 and 0.998 for TiO2/UV and TiO2, respectively. Conclusions:Overall, it could be assumed that AOPs are reliable techniques to purify raw and complex raw industrial effluents.

Petroleum crude oil is transported on a global scale through marine vessels and barges by the sea route. Oil spills into the marine environment are known to cause long term effects on the health of marine life and human beings in addition to harming the eco-system. In this study, petroleum refinery effluent samples were collected and analyzed for their physico-chemical properties. Thirty two bacterial strains were isolated by direct isolation and post enrichment in crude oil. Among these, fourteen isolates could utilize petroleum hydrocarbons as sole carbon source on Bushnell Hass Agar plates supplemented with crude oil within 2 days. Out of these fourteen strains, four could decolorize 2,6-dichlorophenol indophenol within 36 h completely. They were identified as Bacillus cereus WD22, Pseudomonas aeruginosa WD23 and WDE11 (2 strains) and Acinetobacter baumannii OCB1 by 16sRNA sequencing. All four strains could tolerate salinity up to 4.0%w/v. The reduction in total petroleum hydrocarbons in sea water spiked with crude oil (1.0%v/v) supplemented with trace amounts of glucose and yeast extract was studied by gravimetric analysis. P. aeruginosaWD23 degraded 27.25% of supplied petroleum crude oil under limited nutrient conditions in seawater in 15 days.

Ultrasonic irradiation is one of the advanced oxidation methods used in wastewater treatment. In this study, ultrasonic treatment of petroleum refinery effluent was examined. An ultrasonic homogenizator with a 20 kHz frequency and an ultrasonic bath with a 42 kHz frequency were used as a source for ultrasound. The effects of parameters such as ZnO amount, ozone saturation time, and type of ultrasound source on the degradation of petroleum refinery effluent were investigated. The degradation of petroleum refinery effluent was measured as a change in initial chemical oxygen demand (COD) and with time. According to the results, degradation increased with the addition of ZnO in an ultrasonic probe. There was also a positive effect of ozone saturation before sonication then applying ultrasound on the degradation for an ultrasonic probe. It was observed that there was no positive effect of ZnO addition and ozone saturation on degradation for an ultrasonic bath.

Catalytic thermolysis of petroleum refinery wastewater was investigated as a pretreatment process. Effects of various parameters like temperature, pH, dose of catalyst and time were investigated for chemical oxygen demand (COD), turbidity, and element reduction. CuSO4, FeSO4, FeCl3, and 1:1 ratio (v:v) mixture of CuSO4 and FeCl3 were used as a catalyst. The maximum reduction of COD and turbidity were 90 and 98% by mixture (1:1) of CuSO4 and FeCl3 at 70 °C, 7 pH, 1.0 kg/m3 dose in 90 min reaction time. The removal of an element like Cr, Mn, Ni, and Pb was analyzed by ICP-OES. The sludge precipitated after catalytic thermolysis was characterized using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), Fourier transform infrared (FTIR) and thermo-gravimetric analysis (TGA)/derivative thermal analysis (DTA) analyses. Sludge from CuSO4 and mixture of CuSO4 and FeCl3 treatment has a compact structure with irregular granule which favors adsorption. [ABSTRACT FROM AUTHOR]

Petroleum crude oil is transported on a global scale through marine vessels and barges by the sea route. Oil spills into the marine environment are known to cause long term effects on the health of marine life and human beings in addition to harming the eco-system. In this study, petroleum refinery effluent samples were collected and analyzed for their physico-chemical properties. Thirty two bacterial strains were isolated by direct isolation and post enrichment in crude oil. Among these, fourteen isolates could utilize petroleum hydrocarbons as sole carbon source on Bushnell Hass Agar plates supplemented with crude oil within 2 days. Out of these fourteen strains, four could decolorize 2,6-dichlorophenol indophenol within 36 h completely. They were identified as Bacillus cereus WD22, Pseudomonas aeruginosa WD23 and WDE11 (2 strains) and Acinetobacter baumannii OCB1 by 16sRNA sequencing. All four strains could tolerate salinity up to 4.0%w/v. The reduction in total petroleum hydrocarbons in sea water spiked with crude oil (1.0%v/v) supplemented with trace amounts of glucose and yeast extract was studied by gravimetric analysis. P. aeruginosa WD23 degraded 27.25% of supplied petroleum crude oil under limited nutrient conditions in seawater in 15 days. [ABSTRACT FROM AUTHOR]

This study aims to evaluate membrane bioreactor (MBR) performance in a pilot scale to treat petroleum refinery effluent, and has been primarily focused on (1) investigation of dynamics of organic matter removal; (2) characterization of membrane fouling under real hazardous events; (3) evaluation of the effect of fouling on membrane lifetime; and (4) estimate the membrane lifetime. The results have shown that the MBR was able to effectively reduce COD, NH-N, turbidity, color, phenol and toxicity, and bring them to the levels required to meet disposal and non-potable water reuse standards. The FTIR results showed that organic matter was removed by biological oxidation and/or retained by adsorption in the biological sludge, or retention in the UF membrane, and that SMP was produced during the treatment. In terms of membrane permeability, the results showed that soluble fraction of mixed liquor contributed significantly to membrane fouling. And finally, considering the concept of lifetime based on permeability decline, a membrane lifetime of 7 years is expected. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) being an emerging technology have been the research focus of increasing interest due to their sustainable capacity for wastewater treatment together with electricity generation. This study investigated the potential use of pure culture Bacillus cereus and Clostridium butyricum as inoculums in MFCs for simultaneous bioelectricity generation and treatment of petroleum refinery effluent. Double-chambered MFCs was used for the study and operated over four-batch cycles for 30 cumulative days but with different external resistances. The influent concentrations of chemical oxygen demand (COD) and total organic compound (TOC) in the petroleum refinery effluent was 970 mg/l (ppm) and 156 g/l, respectively. Experimental results indicated that the MFCs with the use of Bacillus cereus as biocatalyst achieved its maximum COD removal, TOC degradation and coulombic efficiencies of 70%, 88.7% and 19.21%, respectively; while with the use of Clostridium butyricum, it achieved the highest COD removal, TOC degradation and coulombic efficiencies of 54.2%, 68.7% and 17.84%, respectively. A maximum voltage of 450 mV and highest power density of 17066.67 mW/m2 with a maximum current density of 1.270 mA/m2 was obtained in regard to the external resistor of 1000 Ω using Bacillus cereus as biocatalyst. Similarly, using Clostridium butyricum as biocatalyst the maximum voltage of 370 mV and highest power density of 8816.17mW/m2 with a maximum current density of 0.913 mA/m2 was achieved. The study demonstrated that both Bacillus cereus and Clostridium butyricum has strong potentials to be used as inoculums for simultaneous bioelectricity generation and treatment of petroleum refinery effluent in MFCs. [ABSTRACT FROM AUTHOR]

The petroleum refinery industry generates a significant amount of wastewater that contains a high level of organic matter, which calls for effective and costly treatments. In this research, the effectiveness of the petroleum refinery effluent (PRE) treatment with physicochemical process of combined adsorption and coagulation was evaluated. The effects of initial pH, hydraulic condition , and combined sequence of treatment process, different treating reagent types and dosages on the chemical oxygen demand (COD) removal were investigated. Additionally, the elimination efficiency of pollutant wastewater was monitored by gas chromatography–mass spectrometry (GC–MS), and Fourier transformed infrared (FT-IR) spectrophotometer was adopted to describe the structure of the wastewater. Wooden activated carbon was chosen as adsorbent at the dosage of 10 g/L as a primary treatment, and 1500 mg/L polymeric magnesium ferric sulfate was used in coagulation. Results showed that adsorption and subsequent coagulation displayed the best performance when initial pH was 9 at shear rates (G) of G1 = 65 s−1and G2 = 20 s−1, which reached maximal removal rate of COD and total organic carbon GC–MS testing result revealed that adsorption was effective in phenols and iso-alkanes removal, whereas coagulation was good at removing esters andn-alkanes. [ABSTRACT FROM PUBLISHER]

In this study, an upflow anaerobic sludge blanket (UASB) bioreactor at the mesophilic temperature (38ºC) was successfully used for the treatment of petroleum refinery effluents. Response surface methodology (RSM) was applied for the design and analysis of experiments to predict the behavior of the initial COD and the hydraulic retention time (HRT) in the bioreactor. A statistical analysis indicated that the models adequately represented the experimental data. At the optimal conditions, the effluent COD was 120 mg/L, the VSS effluent was 0.4 mg/L and the biogas rate was 0.025 L biogas/L feed. day. The Monod, First-order, Grau and modified Stover-Kincannon models were applied to determine the substrate removal kinetics in the reactor. The results obtained were described the best by the modified Stover-Kincannon model. The kinetic of methane production was also studied. The product yield coefficient, YM, was 0.69 LCH4/g CODremoved. [ABSTRACT FROM AUTHOR]

The toxicity of phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol on Pseudomonas, Bacillus and Escherichia species isolated from petroleum refinery wastewater was assessed via inhibition of dehydrogenase enzyme activity. At low concentrations, 2-nitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol stimulated dehydrogenase activity and at sufficient concentrations, phenolic compounds inhibited dehydrogenase activities. Generally, phenol is less toxic than substituted phenols. Estimations of the degree of inhibition/stimulation of dehydrogenase activities showed significant dose-dependent responses that are describable by logistic functions. The toxicity thresholds varied significantly (P < 0.05) among the bacterial strains and phenolic compounds. The median inhibitory concentrations (IC50s) ranged from 4.118 ± 0.097 mg.L-1 for 4-nitrophenol against Pseudomonas sp. DAF1 to 1407.997 ± 7.091 mg.L-1 for phenol against Bacillus sp. DISK1. This study suggested that the organisms have moderate sensitivity to phenols and have the potential to be used as indicators for assessment of chemical toxicity. They could also be used as catalysts for degradation of phenols in effluents.

We investigated a novel wastewater treatment method for the remediation of crude oil refinery effluents with large number of recalcitrant organic compounds. The treatment system consists of an up-flow anaerobic sludge blanket (UASB) reactor and an aerobic packed-bed biofilm reactor (PBBR) in combinatory pattern to increase the efficiency of treatment and to remove polycyclic aromatic hydrocarbons (PAHs) of the wastewater. The mean chemical oxygen demand (COD) removal efficiency in the UASB reactor and PBBR over 118 days of sampling was 68.48% and 38.28%, respectively. The total COD removal efficiency of the system was 81.07%. The GC-MS abundance and area values for each of the substances in the effluent decreased greatly from the corresponding value in the influent. Specifically, the PAHs were totally removed during the treatment process. This study presents a feasible technology for the treatment of refinery effluents. [ABSTRACT FROM AUTHOR]

Petroleum refinery effluents (PREs) are wastewaters characterised by high values of chemical oxygen demand (COD) and total organic carbon (TOC). Mineralisation of PRE is not commonly reported. For Fenton oxidation, in particular, reported PRE mineralisation is low. In this paper, treatability of a petroleum refinery effluent using a Fenton-like oxidative reaction is described. A statistically designed experimental matrix was used to evaluate the individual and combined effects of process variables based on a five-level central composite design (CCD). Response surface methodology (RSM) was employed to optimise the parameters of interest (COD and TOC), and response surface equations were subsequently developed. These parameters were optimised from studies of the independent variables, for reaction time [tr] = 30-240 min, molar ratio of hydrogen peroxide to the organic wastewater [H2O2]:[PRE] = 2-12 and mass ratio of hydrogen peroxide to catalyst [H2O2]:[Fe3+] = 5-20. The COD and TOC of the PRE at an initial pH of 7 were 1343 mg O2/L and 398 mg C/L, respectively. Under optimal conditions, maximal TOC and COD reduction achieved within 30 min of oxidation reaction were 70% and 98.1%, respectively. The obtained models had correlation coefficients (R2 and Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed) of 0.9984 and 0.9916 for TOC and 0.9636 and 0.8835 for COD. At a pH of 3, corresponding optimal oxidation conditions were found to be [H2O2] = 1008.0 mM and [Fe3+] = 686.0 mg, that is, a molar ratio of [H2O2]:[PRE] = 12 and mass ratio of [H2O2]:[Fe3+] = 5. [ABSTRACT FROM AUTHOR]

Abstract: An upflow anaerobic sludge blanket (UASB) bioreactor was successfully used for the treatment of petroleum refinery effluent. Before optimization, chemical oxygen demand (COD) removal was 81% at a constant organic loading rate (OLR) of 0.4kg/m3 d and a hydraulic retention time (HRT) of 48h. The rate of biogas production was 559mL/h at an HRT of 40h and an influent COD of 1000mg/L. Response surface methodology (RSM) was applied to predict the behaviors of influent COD, upflow velocity (V up) and HRT in the bioreactor. RSM showed that the best models for COD removal and biogas production rate were the reduced quadratic and cubic models, respectively. The optimum region, identified based on two critical responses, was an influent COD of 630mg/L, a V up of 0.27m/h, and an HRT of 21.4h. This resulted in a 76.3% COD removal efficiency and a 0.25Lbiogas/Lfeedd biogas production rate. [Copyright &y& Elsevier]

Abstract: Petroleum refineries release wastewater, which is rich in organic pollutants and cannot be treated easily. This study presents the treatment of petroleum refinery wastewater using nanoscale zero valent iron (NZVI) in the presence of ultrasonication. NZVI characteristics were analyzed using SEM and XRD. The influence of NZVI dosage and initial pH on % chemical oxygen demand (COD) reduction was studied. From the results, it can be inferred that a dosage of 0.15g/l and an initial pH are optimum for the effective degradation of effluents. The degradation data were found to follow first order kinetics. The results indicate that using NZVI in combination with ultrasonication is an efficient method for the treatment of petroleum refinery wastewater. [Copyright &y& Elsevier]

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Abstract: Removal efficiency of organic contaminants and reduction of toxicity (Microtox) in the secondary petroleum refinery and pulp mill effluents using two freezing processes, unidirectional downward freezing (UDF) and the spray freezing, was evaluated in this experimental study. The effect of the freezing temperature, initial feed water impurity concentration, mixing of the freezing liquid and the duration of freezing on the impurity removal efficiency was examined. Effective removal of chemical oxygen demand (COD) and total organic carbon (TOC) causing materials from both effluents, color causing materials in the pulp mill effluent, and removal of linoeic and abietic acids in the meltwater of the spray ice was achieved by freezing only 70% of the feed water. Close association of effluent toxicity with TOC and COD concentrations was observed when EC20 was used to measure the toxicity. Mixing of the freezing liquid significantly improved the impurity removal efficiency of the UDF process, reduced the influence of freezing temperature and initial feed water impurity concentration. Greater impurity removal efficiency was observed for the spray ice with longer storage time. The impurity removal efficiency of the spray freezing process was similar to that of the UDF without mixing. [Copyright &y& Elsevier]