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Mohammed‐Osama J. Azzam Kamal Al‐Malah Ziad Al‐Gazzawi Saad A. Al‐Omari 《洁净——土壤、空气、水》2010,38(9):822-830
Olive mills wastewater (OMW) is a critical environmental problem in the Mediterranean area due to its extremely high levels of COD and phenols. In this study, a group of adsorption experiments were conducted to investigate the dynamic response of the pH, COD, phenols, TSS, TDS, and TS concentrations of pretreated OMW, using different concentrations of activated carbon as adsorbent. The pretreatment included sedimentation and filtration of OMW. The pretreated OMW was then subjected to adsorption. A series of adsorption steps in stirred batch vessels were studied, namely, one stage, two‐stage countercurrent, and three‐stage countercurrent adsorption systems. A combined two‐ two‐stage countercurrent adsorption steps were also studied. Experimental results showed that such treatment protocols were promising. For example, a treatment protocol composed of a three‐stage countercurrent adsorption process using activated carbon of concentration of 24 g/L of OMW was able to reduce the COD from 60 000 mg/L down to 22 300 mg/L, while phenols were reduced from 450 to 15 mg/L. 相似文献
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In this work, the treatment of actual agro‐industrial wastewaters (IWW) by a UV/H2O2 process has been investigated. The aqueous wastes were received from industrial olive oil mills and then treated by laboratory scale physicochemical methods, i. e., coagulation using ferrous and aluminum sulfate, decantation, filtration and adsorption on activated carbon. These wastes are brown colored effluents and have a residual chemical oxygen demand (COD) in the range of 1800 to 3500 mgO2 L–1, which cannot be further eliminated with physicochemical processes. The UV/H2O2 treatments were carried out under monochromatic irradiation at 254 nm using a thermostated reactor equipped with a mercury vapor lamp located in an axial position. The effects of initial H2O2 concentration, initial COD, pH and temperature have been studied in order to determine the optimum conditions for maximum color and COD removals. The experimental results reveal the suitability of the UV/H2O2 process for both removal of high levels of COD and effectively decolorizing the solution. In particular, 95% of color removal and 90% of COD removal were obtained under conditions of pH = 5 and 32°C using 2.75 g H2O2 g–1 COD L–1 during 6 h of UV‐irradiation. The treatment is unaffected by pH over the range 2 to 9. In addition, the COD removal is improved by increasing the temperature, whereas the color removal has not been affected by this parameter. The results show that the hydroxyl radicals generated from the catalytic decomposition of H2O2 by UV‐irradiation of the solution could be successfully used to mineralize the organics contained in IWW. The mineralization of the organics seems to occur in three main sequential steps: the first is the rapid decomposition of tannins leading to aromatic compounds, which are confirmed by the decolorization of the IWW; the second step corresponds to the oxidation of aromatics leading to aliphatic intermediates, which occurs by the cleavage of an aromatic ring, and is established by the removal of aromatics, and the final step is the slow oxidation of the aliphatic intermediates, which is measured by the COD removal. 相似文献
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Xue Song Wang Yu Jun Tang Li Fang Chen Fei Yan Li Wen Ya Wan Ye Bin Tan 《洁净——土壤、空气、水》2010,38(3):263-267
Zero‐valent, iron‐encapsulated alginate beads were synthesized and were applied for the removal of Cr(VI) from aqueous solutions. The effects of several important parameters including solution pH, contact time, initial concentration and reaction temperature on Cr(VI) removal levels were investigated in batch studies. An initial solution pH of 1.0 was seen to be most favorable for Cr(VI) removal. The removal process was quick and almost 80% of the removal was attained within 60 min. The kinetic data followed the second‐order equation well. The Cr(VI) removal was almost reaction temperature‐independent and decreased with an increase in Cr(VI) initial concentration. The removal of Cr(VI) by iron‐encapsulated alginate beads was found to be significantly higher than that of non‐encapsulated alginate beads. 相似文献
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In this study, the oxidative decolorization of C.I. reactive yellow 145 (RY 145) from synthetic textile wastewater including RY 145 and polyvinyl alcohol by Fenton and sono‐Fenton processes which are the combination of Fenton process with ultrasound has been carried out. The effects of some operating parameters which are the initial pH of the solution, the initial concentration of Fe2+, H2O2, and the dye, temperature, and agitation speed on the color and chemical oxygen demand (COD) removals have been investigated. The optimum conditions have been found as [Fe2+] = 20 mg/L, [H2O2] = 20 mg/L, pH 3 for Fenton process and [Fe2+] = 20 mg/L, [H2O2] = 15 mg/L, pH 3 for sono‐Fenton process by indirectly sonication at 35 kHz ultrasonic frequency and 80 W ultrasonic power. The color and COD removal efficiencies have been obtained as 91 and 47% by Fenton process, and 95 and 51% by sono‐Fenton processes, respectively. Kinetic studies have been performed for the decolorization of RY 145 under optimum conditions at room temperature. It has been determined that the decolorization has occurred rapidly by sono‐Fenton process, compared to Fenton process. 相似文献
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Leopoldo Martínez Nieto Gassan Hodaifa Salvador Rodríguez José A. Giménez Javier Ochando 《洁净——土壤、空气、水》2011,39(10):949-955
Flocculation and sedimentation of particles are essential to many environmental and industrial processes. Solid–liquid separation in olive‐oil mill wastewater treatment by means of Fenton system is the key to work continuously and maintain a constant outlet flow of clarified water at the end of the oxidation process. Natural sedimentation is not capable to eliminate the sludge formed. The efficiency of flocculation operation using different flocculants as QG‐2001, QG‐2002, DQGALFLOC‐130H, and Nalco‐77171 was investigated. The optimum dosage of each flocculant, 150, 2.5, 66, and 6 mg dm?3, respectively, was determined. The results revealed that the best flocculant was Nalco‐77171, which determined 13.5% v/v final sludge separation and 86.5% v/v final clarified water obtained. Kinetics of sludge removal in the transition zone was adjusted to power law, v/v0 = Ktε, where the exponent, ε, varied in the range 0.141–0.670. 相似文献
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The present work focuses on the performance of Fenton, sono‐Fenton, and sono‐photo‐Fenton processes for the oxidation of phenol present in aqueous solution. The effects of H2O2 concentration, Fe2+ concentration, pH, and initial phenol concentration on the oxidation of phenol were studied. The optimum Fe2+ and H2O2 concentrations for the Fenton process were 45 and 800 mg/L, respectively. For the sono‐Fenton process, the optimum Fe2+ and H2O2 concentrations were 30 and 800 mg/L, respectively. The optimal conditions for the sono‐photo‐Fenton process were found to be 20 mg/L of Fe2+ and 700 mg/L of H2O2. The optimum pH was found to be 3 for the processes investigated in the present study. The analysis of results showed that the sono‐photo‐Fenton method reduced the Fe2+ concentration by 30–50% and the H2O2 concentration by 12.5%. It was found that the sono‐photo‐Fenton technique showed better performance than the Fenton and sono‐Fenton processes for the oxidation of phenol. A lumped kinetic model was used to predict the chemical oxygen demand reduction and the model was found to fit the data. 相似文献
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This study attempts to explore the possibility of treating dye solutions containing Disperse Yellow 119 and Disperse Red 167 by Fenton and Fenton under solar‐light oxidation processes. Experiments were conducted to examine the effects of various operating conditions on the performance of the treatment systems. The Fenton results showed that 98.6% spectral absorption coefficient (SAC) and 90.8% chemical oxygen demand (COD) removals were proved at pH 3, 50 mg/L Fe2+, and 75 mg/L H2O2, 15 min oxidation time for Disperse Yellow 119. After 40 min solar irradiation time during Fenton process the SAC removal was 99.1%. COD reduction of about 98.3% was observed at the same time. It was also obtained as 97.8% SAC and 97.7% COD removal with pH 3, 75 mg/L Fe2+, 100 mg/L H2O2, and 25 min oxidation time for Disperse Red 167 at this optimum conditions. For Disperse Red 167 during Fenton under solar light process, after 40 min of solar irradiation time the SAC and COD reduction were obtained 99.3 and 98.4%, respectively. 相似文献
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The feasibility of pilot‐scale mineralization of organic pollutants in wastewaters using the Electro‐Fenton® process is demonstrated. The treatment was applied in a continuous‐flow reactor, to solutions of nitrobenzene, 2,4‐D and benzoic acid and to actual wastewaters from a fine chemicals company along with a pulp and paper company. The results showed mineralization yields from 60 to 84% by simply applying the Electro‐Fenton® process. When a subsequent exposure to sunlight was carried out (Helielectro‐Fenton method), this mineralization almost went to completion, except for the effluent from the fine chemicals industry. 相似文献
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Design of Fenton and photo‐Fenton reactions was partially automated by using sequential injection analysis (SIA) and response surface methodology for the treatment of a wastewater sample from a coatings industry. The extension of both Fenton and photo‐Fenton reactions was evaluated by the percentage of total organic carbon (TOC) remaining in solution after 15 min of reaction. Use of small volumes of sample and reagents, as well as easy solution handling, were the remarkable features of the proposed system. The highest percentage of TOC removal (79%) was obtained by the photo‐Fenton reaction at the following initial mass‐based concentration ratios: H2O2/TOC = 10, H2O2/FeSO4 = 50, and pH 2.5. The best result for Fenton reaction indicated a TOC removal of only 45%, obtained at H2O2/initial TOC = 20, H2O2/FeSO4 = 30, and pH 2.5. The SIA system was designed to dispense reagents to the sample flasks and to drive the sample intended to photo‐Fenton reaction through a homemade photo‐reactor. Modifications in chemical parameters of the reactions were achieved via the software commanding the SI system, without the need for physical reconfiguration of reagents around the selection valve. 相似文献
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Soil contaminated with hydrocarbons is a current problem of great importance. These contaminants may be toxic, can retain water and block gas exchange with the atmosphere, which produces a poor-quality soil unsuitable for ecological health. Electroremediation is among the treatments for the removal of such contaminants. In this research, a pilot-level electroremediation test was applied using a circular arrangement of electrodes with a Ti cathode at the middle of the cell surrounded by six IrO2–Ta2O5 | Ti anodes. The presence of an NaOH electrolyte helps to develop the electromigration and electro-osmosis of gasoline molecules (at 1126 mg kg−1) surrounded by Na+ ions. The hydrocarbons are directed towards the cathode and subsequently removed in an aqueous Na+ – hydrocarbon solution, and the –OH migrates to the anode. During electrokinetic treatment, the physicochemical characteristics of the soil close to either the cathode or anode and at the half-cell were evaluated during the three weeks of treatment. During that time, more than 80% of hydrocarbons were removed. Hydrocarbons removed by the electrokinetic treatment of gasoline-polluted soil were collected in a central wastewater compartment and subsequently treated with a Fenton-type advanced oxidation process. This achieved more than 70% mineralization of the hydrocarbons to CO2 and H2O within 1.5 h; its low toxicity status was verified using the Deltatox® kit test. With this approach, the residual water complied with the permissible limits of COD, pH, and electrical conductivity for being discharged into water bodies, according to Mexican norm NOM-001-SEMARNAT-1996. 相似文献
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Catechol is one of the most abundant phenolic components of olive mill wastewaters. In this article, the mineralization of this compound in synthetic aqueous solutions by the Fenton and photo‐Fenton processes is studied. It has been found that for 1.44 mM catechol, the total organic carbon of solutions is reduced about 94.4% at best after 60 min of Fenton treatment at optimized conditions of pH 3.0, 0.2 mM Fe2+, 7.09 mM H2O2, and 25°C. A faster and overall mineralization is attained by applying photo‐Fenton with UVA irradiation. o‐Benzoquinone, 1,2,3‐trihydroxybenzene and 1,2,4‐trihydroxybenzene were identified by GC–MS as primary quinonic and polyhydroxylated derivatives. Small amounts of generated carboxylic acids like muconic, maleic, malonic, acetic, oxalic, and formic acids were detected by ion‐exclusion chromatography. The Fe(III) complexes of these acids persist in the medium under Fenton conditions, while their photolysis by UVA light and that of other by‐products account for by the faster degradation and total mineralization achieved in the photo‐Fenton process. A reaction sequence for catechol mineralization by Fenton and photo‐Fenton involving all intermediates detected is proposed. 相似文献
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In order to determine the interference caused by chloride ions in Chemical Oxygen Demand (COD) measurements, synthetically prepared samples with various COD and chloride concentrations were analyzed. In addition, statistical analyses of the results were performed to calculate the real COD caused by the presence of organic substances in chlorinated wastewaters. The results of regression analyses showed good correlation between chloride concentrations and COD levels. A mathematical model is proposed on the basis of the statistical analyses. To calculate the real COD value of a wastewater sample, firstly, the chloride and interfered (or apparent) COD concentrations should be measured and then interference due to the chloride is calculated using the model equation proposed in this study. The real COD value was found by subtracting the COD due to chloride from the apparent COD. The reliability of the proposed model was also validated on real domestic wastewater samples, which were mixed with real seawater in various volumetric ratios to generate a range of salinity concentrations. These real saline samples gave good estimates of real COD with the results indicating that the proposed model can be used with acceptable confidence. 相似文献
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MCPA (4‐chloro‐2‐methylphenoxyacetic acid) is an acidic herbicide widely used on olive crops in Spain. Due to its anionic form at natural soil pH, there is high risk of leaching and groundwater contamination by the use of this herbicide. The aim of this work was to study the effects of organoclay‐based formulations of MCPA and olive oil waste amendment on MCPA leaching in a sandy loam soil. For this purpose, batch adsorption and column leaching studies were performed. The organoclays used to prepare the clay‐based formulations of MCPA were obtained by treating Wyoming montmorillonite (SWy‐2) and Arizona montmorillonite (SAz‐1) with an amount of hexadecyltrimethylammonium (HDTMA) cation equal to 100% of the CEC of the montmorillonites. The organic residue used in this study was a solid waste from olive oil production (olive oil waste, OOW). The soil was amended with the organic residue at the rate of 10% (w/w). Batch release and column leaching studies indicated that organoclay‐based formulations of MCPA reduced the release rate and the leaching of the herbicide as compared to the use of a conventional formulation containing the herbicide in an immediately available form. The increase in soil organic matter of the soil upon amendment with the organic residue also resulted in greater adsorption and reduced leaching of MCPA in the soil. Accordingly, both the use of organoclay‐based formulations and the amendment of soil with OOW are proposed as efficient strategies to reduce extensive leaching losses associated with the application of MCPA in high‐risk scenarios, such as Mediterranean olive groves. 相似文献
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María Mar Gil‐Díaz Araceli Pérez‐Sanz María Ángeles Vicente María Carmen Lobo 《洁净——土壤、空气、水》2014,42(12):1776-1784