Dheeaa al deen Atallah

The present study is conducted to compare the performance of different oxidation processes such as the solar photo-Fenton, the solar photocatalyst of TiO 2 and solar photocatalyst of TiO 2 /Fenton process for the treatment of petroleum wastewater from Sohar oil refinery (SOR) by a central composite design (CCD) with response surface methodology (RSM). The degradation efficiency is evaluated in terms of chemical oxygen demand (COD) and total organic carbon (TOC) reductions. The solar photocatalyst of TiO 2 /Fenton method improved the performance of photocatalyst TiO 2 in the normal value of pH (7) for petroleum wastewater, therefore no need to adjust pH during this treatment. In acidic conditions pH <7, the solar photo-Fenton process is more efficient than the solar photocatalyst of TiO 2 process, while it is less efficient than the solar photocatalyst of TiO 2 process in alkaline conditions pH >7. The TiO 2 dosage and pH are the two main factors that improved the TOC and COD removal in the solar photocatalyst of TiO 2 /Fenton and the solar photocatalyst of TiO 2 processes while the pH and H 2 O 2 concentration are the two main factors in the solar photo-Fenton process. Keywords: The solar photo-Fenton process; The solar photocatalyst of TiO 2 process; The solar photocatalyst of TiO 2 /Fenton process; The petroleum wastewater; Chemical oxygen demand; Total organic carbon

The objective of this study was to investigate the performance of employing solar photo-Fenton to treat petroleum wastewater from Sohar oil refinery, evaluate this process by a central composite design with response surface methodology and evaluate the relationship among operating variables such as pH, H 2 O 2 dosage, Fe ?2 dosage, and reaction time to identify the optimum operating conditions. Quadratic models proved to be significant with very low probabilities (\0.0001) for the following responses: total organic carbon (TOC) and chemical oxygen demand (COD). The optimum conditions were H 2 O 2 dosage (850 mg L-1), Fe ?2 dosage (60 mg L-1), pH (3.68) and reaction time (127 min) in this method. The experimental results of the maximum TOC and COD removal rates corresponded good with the predictions, which were 59.3 and 74.7 %, respectively. This method achieved well degradation efficiencies for TOC and COD and reduced the treatment time comparing with the previous work. Keywords Photo-Fenton Á Petroleum wastewater Á Chemical oxygen demand (COD) Á Total organic carbon (TOC)

The aim of this study is to investigate the performance of employing the solar photo-catalyst of TiO 2 to treat petroleum wastewater from Sohar oil Refinery (SOR), evaluate the performance of employing this process by a central composite design (CCD) with response surface methodology (RSM) and evaluate the relationships among operating variables such as TiO 2 dosage, pH, C 0 of COD, and reaction time to identify the optimum operating conditions. Quadratic models prove to be significant with very low probabilities (<0.0001) for the following two responses: total organic carbon (TOC) and chemical oxygen demand (COD). TiO 2 dosage and pH are the two main factors that improved the TOC and COD removal while C 0 of COD and reaction time are the actual factors. The optimum conditions are a TiO 2 dosage (0.6 g/L), C 0 of COD (1600 ppm), pH (8), reaction time (139 min) in this method. TOC and COD removal rates are 15.5% and 48.5%, respectively. The predictions correspond well with experimental results (TOC and COD removal rates of 16.5%, and 45%, respectively). Using renewable solar energy and treating with minimum TiO 2 input make this method to be a unique treatment process for petroleum wastewater.

The objective of this study is to investigate the performance of employing Fenton’s reagent in the solar
photo-catalyst of TiO2 to treat petroleum wastewater from Sohar oil Refinery, Oman. A central composite
design (CCD) with response surface methodology (RSM) is applied to evaluate the relationships between
operating variables, such as TiO2 and Fenton dosage, pH, and reaction time, to identify the optimum
operating conditions. Quadratic models for the following three responses prove to be significant with
very low probabilities (<0.0001): chemical oxygen demand (COD), total organic carbon (TOC) and
residual iron (Fe). The obtained optimum conditions include a reaction time of 90 min, 0.66 g/L TiO2, 0.5 g/
L H2O2, 0.01 g/L Fe2+, and pH 4.18. TOC and COD removal rates are 62% and 50%, respectively, and 0.8 ppm
residual iron is obtained. The predictions correspond well with experimental results (TOC and COD
removal rates of 64%, and 48%, respectively, and 0.5 ppm residual iron). The solar photo-Fenton process
has well efficient for petroleum wastewater treatment in acidic conditions pH < 7 and more economic by
free energy.

ABSTRACT
The purpose of this study is to investigate the treatment of petroleum-extraction wastewater by means of a photo-Fenton process using sunlight as irradiation source. The objective of this study was to investigate the application of Photo-Fenton to the treatment of wastewaters contaminated with hydrocarbon oil. The AOPs investigated are Fe2+/H2O2/Sunlight (Photo-Fenton’s reagent) which may be used as an alternative to, or in conjunction with, conventional treatment techniques. The recently developed photo Fenton treatment is based on the hydroxyl radical generation by a mixture of H2O2 to Fe+2 ions.
Preliminary experiments are conducted, using the photo-Fenton processes. Batch experiments revealed that the photo-Fenton reaction is very fast and reaches an ultimate COD removal of 84%, due to the formation of iron complexes. Experiments are also conducted in a continuous mode; operating one Fenton stirred reactor (1 L) and one photo-Fenton reactor (1.6 L) in series. COD removals 66% are reached at 5 hours.
Different mass ratios of Fe2+/H2O2 were tested and the results showed that the efficiency of the photo-Fenton reactions increases as the concentration of hydroxyl radicals (•OH) increases.
The combinations of sunlight/H2O2/Fe+2 processes are investigated on treatment of Sohar oil refinery wastewater, Oman. Treatment of oil refinery wastewater is carried out by batch and continuous oxidation processes. The optimal mass ratio for H2O2/Fe+2 yielding the highest TOC removal is found to be 12.5 corresponding to 1 g 1-1 H2O2 and 0.08 g l-1 Fe+2 concentrations for 120 minutes reaction time. Photo-Fenton process, after the total reaction time (5h), H2O2: 1 g l-1 and Fe+2: 0.08g l-1, gave a maximum degradation of TOC of 64% and a COD reduction of 84%. COD removal efficiency for Sunlight/ H2O2/Fe+2 processes is 23%, 72%, and 84 when initial COD was 1068, 1320, and 2150 mg l-1, respectively. Laboratory-scale batch and continuous-flow experiments are undertaken. The photo-Fenton parametric concentrations to maximize TOC & COD removal are optimized: pH = 2, H2O2 = 1 g/L, and Fe2+ = 0.08 g/L.

Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed to the environment without any harmful effects. In the present study, Photo-catalytic activities of Titanium dioxide (TiO2 P25) under sunlight processes are investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high Chemical Oxygen Demand (COD) wastewater from Petroleum Refinery Wastewater plant in Sohar Oil Refinery and develop a batch photo-catalytic reactor and continuous reactor under same condition and evaluate their efficiency. This research addresses the photo degradation efficiency of Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) and the generation of hydroxyl radicals using the Sunlight/TiO2 system. All experiments are conducted to investigate the effects of parameters such as, catalyst dosage, initial concentration of COD and TOC, initial pH and irradiation time under sunlight and also the industrial effluent is characterized. Experimental results revealed that the photo-catalytic activity of the TiO2 for the COD removal efficiency is highest with using 1gm/l TiO2 dosage. Optimization of catalyst dose, pH and COD concentration has been done.
A maximum COD removal of 85% from the effluent is achieved in 240 min. The percentage removal of TOC reaches to a maximum for a catalyst loading of 1.5gm/L which is 18% in 300 minutes of reaction time period. It can be used as a treatment step in the high organic wastewater treatment during the primary stage.

Abstract
In these years, due to the increasing presence of molecules in industrial waste water from factories and petroleum refineries, the conventional biological methods cannot be used for complete treatment of the effluent therefore the need to newer technologies to degrade these refractory molecules into smaller molecules became very imperative.
Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters. Fenton’s oxidation was one of the best known metal catalyzed oxidation reactions of water-miscible organic compounds. The mixture of FeSO4 or any other ferrous complex and H2O2 (Fenton’s reagent) at low enough pH, results in Fe2+ catalytic decomposition of H2O2 and proceeds via a free radical chain process that produces hydroxyl radicals which have extremely high oxidizing ability and could oxidize hard to decompose organic compounds in a short time.
This work aims at highlighting Fenton’s oxidation processes operating at ambient conditions viz. photo-catalytic oxidation, Fenton’s chemistry and use of hydrogen peroxide. The pre-oxidation of an extremely polluted pharmaceutical wastewater, Direct Blue 71 (DB71) oil recovery industry wastewater, the fish canning industrial wastewater, Active pharmaceutical intermediates (API) in waste waters by Fenton’s oxidation process to degrade organic pollutants. The work highlights the basics of these individual processes including the reactor design aspects, the optimum parameters such as dosage of ferrous sulfate and hydrogen peroxide, pH and initial concentration of pollutants and a complete overview of the various applications to wastewater treatment by Fenton’s oxidation processes in the recent years.
This study presents a general review on the effectiveness of Fenton’s technique for the treatment of semi-aerobic landfill leachate (Treatment with Fenton’s reagent appears to be an appropriate method for oxidizing recalcitrant

Abstract
Photo-catalytic activity of Titanium dioxide (TiO2) under various irradiation conditions was explored. Experiments were conducted to investigate the effects of parameters such as pH, catalyst dosage, phenol concentration and ultra violet (UV) light intensity. This research addressed the photo degradation efficiency of phenol and the generation of hydroxyl radicals using the UV/TiO2 system. Experimental results revealed that the photo-catalytic activity of the TiO2 was higher under UV light irradiation and indicated that the removal efficiency was highest for phenol when using 0.20 wt% TiO2 dose concentrations. The maximum phenol removal was achieved by using TiO2 for industrial waste water having the initial concentrations of phenol 10 mg/L. Experimental data obtained under different conditions were fitted with kinetic models to describe the dependency of degradation rate as a function of the above mentioned parameters and pseudo-first order was found to describe the phenol degradation with high correlation coefficients compared to pseudo second order. Equilibrium data were analyzed using Langmuir-Hinshelwood kinetics.
Keywords: Photo-catalysis; Phenol, Sunlight; Hydroxyl radical; TiO2; UV; Photo-catalysis; Phenol degradation