Iranian Journal of

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Backgrounds and Objectives: Formaldehyde and phenol are key precursors in the industrial manufacture of resins. Toxicity of these compounds prevents function of microbial populations, so they affect the biological treatments. The aim of this study was investigation of TOC removal from phenol-formaldehyde resin manufacturing wastewater by electrocoagulation using Al- electrodes.
Materials and Methods: This study is the laboratory scale experiment was conducted as a pilot. Wastewater sample was adjusted in the desired pH, electrical conductivity and current density, then it was placed in to the reactor contains four electrodes in aluminum. The electrodes were connected to a DC power supply (0-40V, 0-3A). Samples were collected for TOC determination in the middle of cell at regular time intervals. Collected samples were analyzed using TOC analyzer.
Results:The results indicated that the optimum conditions for the removal of TOC were current density 75 A/m2, solution pH 4 and Conductivity 3 mS/cm. In this condition energy consumption was found 22.5 kWh m-3 after 60 min reaction.
Conclusion: This study shows that electrocoagulation of wastewater from phenol-formaldehyde resin manufacturing can be used as a pretreatment process.

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Background and Objectives: Discharge of textile colored wastewater industries without providing enough treatment in water bodies, is harmful for human and aquatic organisms and poses serious damages to the environment. Most of conventional wastewater treatment methods don't have enough efficiency to remove textile dyes from colored wastewater thus in this research the efficiency of electrocoagulation treatment process with aluminum electrodes for treatment of a synthetic wastewater containing C.I. Reactive Red 198 in batch reactor was studied.
Material and Methods: The experiment conducted in a Plexiglas reactor with a working volume of 2L that equipped with 4 aluminum electrodes. The effects of operating parameters such as voltage, time of reaction, initial dye concentration and interelectrode distance on the color removal efficiency, electrical energy consumption and electrode consumption were investigated.
Results: in the optimum operational condition electrocoagulation, is able to remove color and COD as high as 99.1 and 84.3% in aluminum electrode in 75 minutes at 20 volt and 2 cm interelectrode distance, respectively. Under this condition, operating cost was 2986 rails per cubic meter of treated wastewater. Increase in the interelectrode distance and initial dye concentration,lead to the decrease in efficiency of dye and COD removal.While as the voltage and time of reaction increased, energy consumption, electrode consumption, final pH and color removal, increased too.
Conclusion: electrocoagulation process by aluminum electrode is an efficient and suitable method for reactive dye removal from colored wastewater.

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MicrosoftInternetExplorer4 Background and Objectives:  Presence of humic acids in water resources is important because it is a precursor to disinfection by-products (DBPs) and affects many treatment processes. In this study, we investigated the performance of electrocoagulation process duad with hydrogen peroxide (creating Fenton process) in removal of humic acids (HA) from aqueous environment.
Materials and Methods: The experiments were performed using a 1 L bipolar batch reactor (covered with the aluminum foil) equipped with iron electrodes and connected to electric source having electrical potential 10 V in bipolar mode. First, reactor was filled up using aqueous solution containing 20 mg/L HA. Later, several working parameters, such as initial pH (3, 5, 7, and 8), electrical conductivity produced from adding 1, 1.5, 2 and 3 g/l KCl and reaction time were studied to achieve the highest humic acid removal capacity. To follow the progress of the treatment, hydrogen peroxide (50 mg/l) was added to reactor and then samples of 10 ml were taken at 5, 15, 30, 45, and 60 min and then filtered (0.45 μ) to eliminate sludge formed during electrolysis. Finally, humic acid and iron concentration was measured using TOC analyzer and atomic absorption method respectively.
Results: Results of this study showed that the most effective removal capacities of humic acid (97.19%) could be achieved when the pH was kept 5(KCl 3g/l and reaction time 60 min). The share of Fenton and electrocoagulation process was %7.9 and %92.1 respectively. In addition, our results indicated that the removal efficiency of humic acid with increase of pH and electrical conductivity parameters decreases and increases respectively.
Conclusion: It can be concluded that the Fenton process duad with electrocoagulation process has the potential to be utilized for cost-effective removal of humic acid from aqueous environments.

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MicrosoftInternetExplorer4 Background and Objectives: leachate from municipal solid waste landfill is a strong sewage having hazardous toxic substances. It should be treated by choosing a simple, economical, and eco-friendly method. The aim of this study is reduction of COD from the Qom City landfill leachate using electrocoagulation process.  
Materials and Methods: The experimental study was carried out at bench scale using a batch reactor during 2010.  We used a Plexiglas reactor having 0.7 liter capacity, containing nine plate aluminum electrodes connected to a DC power supply (10-60V, 1-5A). Samples were collected in the middle of cell at regular (every 10 minutes) time intervals. The concentration of COD was determined using a COD analyzer. The effects of different parameters including current density (52.08, 69.44 mA/cm²), electrolyte time (10, 20,30,40,50 and 60 min), and voltage range (10, 20, 30, 40, 50 and 60 volt) were investigated.
Results: For a voltage of 60 V and electrolysis time 60 min, the COD removal efficiency was increased from 48.7% for 52.08 mA/cm² to 77.4% for 69.44 mA/cm². The highest TSS removal efficiency was obtained at the largest current input when the voltage and electrolysis time were kept at 60V and 60 min respectively.
Conclusion: The results showed that the highest COD removal efficiency (77.4%) was obtained when the current density was 69.44 Ma/cm² and the voltage and electrolysis time were kept at 60V and 60 min respectively. Power consumption for this removal level was measured to be 431.26 kWh per kg COD removal. The results obtained revealed that the electrocoagulation technology is an effective treatment process for landfill leachate.

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MicrosoftInternetExplorer4 Background and Objectives: Phenol is one of the most important organic chemicals presenting in water and other environments. It not only brings about hygienic problems but also results in forming 11 toxic priority pollutants in aqueous environments. Hence, the performance of electrocoagulation process using iron and aluminum sacrificial anodes was investigated for removal of phenol.
Materials and Methods: We used a glass tank in 1.56 L volume (effective volume 1 L) equipped with four iron and aluminum plate electrodes to do experiments (bipolar mode). The tank was filled with synthetic wastewater containing phenol in concentration of 5, 20, 40, and 70 mg/l and to follow the progress of the treatment, each sample was taken at 20 min intervals for up to 80 min. The percent of phenol removal was measured at pH 3, 5, 7, and 9 electrical potential range of 20, 40, and 60 volts and electrical conductivity of 1000, 1500, 2000, and 3000 µs/cm.
Results: It was found that the most effective removal capacities of phenol (95 and 98 %) could be achieved when the pH was kept 7 and 5 for iron and aluminum electrodes, reaction time  80 min, electrical conductivity 3000 µs/cm, initial concentration of phenol 5 mg/l, and electrical potential in the range of 20-60 V.
Conclusion: The method was found to be highly efficient and relatively fast compared with existing conventional techniques and also it can be concluded that the electrochemical process has the potential to be utilized for the cost-effective removal of phenol from water and wastewater.

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Background & Objectives: In this study, treatability of wastewater from a laundry unit was investigated by applying electrocoagulation method in which two pairs of aluminum and iron electrodes were utilized. Electrocoagulation is a noble treatment method suitable for different kinds of wastewater which has been given a considerable attentions by researchers recently. Applying direct current to two or several suitable metallic electrode in a batch reactor containing effluent would result in flocks of metal hydroxide. Materials & Methods: We studied the effect of different operational parameters such as pH, electrodes distance, intensity of electrical current, and type of electrodes on the treatment efficiencies. Results: Aluminum electrodes showed better effects on the treatment efficiencies in nitrate and COD removal. Maximum phosphate removal (99.93%)took place at pH=7 using Al electrodes. Whereas, in the case of iron electrode, maximum nitrate and COD removal efficiencies were about 97.60 and 80% at pH=9 and pH=6 respectively. Operational cost analysis showed that the corresponding costs of Al application as an electrode is different from that of iron electrode application. Conclusion: Although application of both iron and aluminum electrodes lead to obtaining considerable removal phosphate, nitrate and COD, iron electrodes could result in reasonable removals to meet Environmental Standards with lower operational costs.

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Background and Objectives: Reduction of released extracellular polymeric substances (EPS) during sludge dewatering is one of the main challenges in sludge treatment process. The aim of this study was to investigate the EPS quantity changes within sludge dewatering by continues ultrasonic – electrocoagulation (US – EC) reactor under different conditions and to determine the most efficient case for reducing these substances. Materials and Methods: In this study, the EPS quantity changes in supernatant were compared after undergoing different conditions of ultrasonic (frequency of 35 and 130 KHz, detention time of 3,5,10, and 30 min) and electrocoagulation (voltage of 20, 30, and 40 V, detention time of 10, 20, and 30 min) processes were compared. Results: The research found that the maximum efficiency of the US-EC reactor was achieved at a frequency of 35 KHz and detention time of 5 min for ultrasonic with voltage of 40 V and at detention time of 30 min for electrocoagulation process as under these conditions total EPS concentration reduced by 69%. Conclusion: According to the results achieved, US – EC reactor significantly reduced the released EPS in supernatant in addition to dewatering sludge.

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