جستجوی مقالات مرتبط با کلیدواژه « electrocoagulation » در نشریات گروه « مهندسی آب »

Cutting oils are used in machining operations to reduce friction, provide lubrication and cooling properties, and prevent corrosion. Biological methods for treating wastewater from these oils have low efficiency. Therefore, other methods should be considered to treat this type of wastewater. The purpose of this study was to investigate the use of electrocoagulation for treatment of wastewater containing cutting oil. In this regard, an electrochemical reactor equipped with two aluminum electrodes and a direct power source was used. The efficiency of the electrocoagulation process was evaluated by measuring the removal percentage of chemical oxygen demand in a certain time range. The effect of various operating parameters such as oil concentration, applied voltage, stirring speed, initial pH, distance, and surface of electrodes on the efficiency of the electrocoagulation process was investigated. The results of the experiments showed that reducing the oil concentration from 3% by volume to 0.5% by volume led to an increase in the efficiency of the purification process up to 97.3%. Increasing the voltage from 40V to 60V reduced the time required for wastewater treatment with the same efficiency from 50 min to 20 min. Decreasing the distance between the electrodes from 6 cm to 2 cm and increasing the effective area of the electrodes from 60 cm2 to 180 cm2 reduced the time required for purification to 20 min. Also, the results of the tests showed that the time required for the purification process at medium stirring speeds (150 rpm) is low. The obtained results showed that the removal percentage of chemical oxygen demand in the neutral environment was high (95.9%). Therefore, due to the simplicity of the method, low operating cost, and the ability to design on an industrial scale, the electrocoagulation method can be used for the treatment of wastewater containing cutting oil.

In the current work, the capability of uncoated titanium anode in the electrochemical treatment of textile wastewater has been investigated with the aim of simultaneously benefiting from electrooxidation and electrocoagulation treatment processes. In the present work, the feasibility of using uncoated titanium anodes for wastewater treatment is studied in an electrochemical pre-pilot set-up with polymeric casing and an electrical supply power of 150 W, operated under galvanostatic regime in batch mode, focusing on the current density as the main subject of assessment, and its performance is evaluated using metrics such as chemical oxygen demand removal and specific energy consumption. A noticeable finding of this work, is the flexibility of the set-up to combine the electrocoagulation and electro-oxidation mechanisms with the current density as the controlling parameter, leading to a remarkable decontamination capability, so that reductions in the total chemical oxygen demand as large as 75–80% in the neutral and 90–95% in the acidic environments were achieved. At low current densities (< 100 μA/cm2), the anodic corrosion was limited and the electro-oxidation was the dominant wastewater treatment mechanism. At high current densities (> 100 μA/cm2), the anodic corrosion was accelerated and the dominant wastewater treatment mechanism was switched to electrocoagulation. Along with the chemical oxygen demand removal capability, the energetic cost-effectiveness of the set-up was a major concern, particularly from the industrial point of view, which was assessed in both neutral and acidic environments, and it was realized optimization occurred at 600 μA/cm2, so that the specific energy consumption and the rate specific energy consumption, were both minimized at this current density, in respective order, 8.9 kWh/kgCOD and 3.52 kWh/kgCOD/h in neutral, and 10 kWh/kgCOD and 2.34 kWh/kgCOD/h in acidic environments.

Antibiotics, which are extensively produced and used all over the world, are considered as emerging contaminants. These organic compounds cannot be efficiently removed by traditional methods applied in wastewater treatment plants. Continuous discharge of antibiotic-containing wastewaters into the aquatic environments can lead to long-term adverse effects on aquatic life and human health. Rifampin is the most widely used antibiotic for treatment of tuberculosis. For this reason, its removal from water and wastewater is of high importance. Electrocoagulation is an advanced treatment method which has been effectively applied for removal of complex organic compounds such as chemical drugs. The main aim of the present study is to investigate the techno-economic aspects of the EC process for removal of RIF antibiotic from aqueous solution. In this study, effects of different parameters including initial pH, voltage, stirring speed, initial RIF concentration, reaction time, inter-electrode distance (die), shape of electrodes and their arrangement inside the reactor were evaluated on RIF removal efficiency using the EC process and its operating costs. The EC process was induced in batch mode using a 1 L reactor and synthetic RIF containing solution. The experiments were designed by one-factor-at-a-time method and relative standard deviation was used to compare the grade of the effect of the parameters on removal efficiency and operating costs of the process. Based on the obtained results, under optimal conditions, i.e., initial pH of 5, die of 1 cm, voltage of 20 volt, stirring speed of 200 rpm, initial RIF concentration of 10 mg/l, reaction time of 30 min and hole-punched shape electrodes in horizontal arrangement, the removal efficiency and the operating costs of the process reached about 92.49% and 89 US$/kg RIF removed, respectively. According to RSD values, among all the parameters investigated, reaction time, initial RIF concentration, voltage and initial pH were distinguished as the most effective ones on both RIF removal efficiency and operating costs. Generally, results of the study showed that the EC process has a high ability for removal of RIF antibiotic from water.

The response surface statistical model developed via the central composite design (CCD) is a tool for optimizing manufacturing processes. Phrmaceutical plants depend on many such processes and i is essential to remove medicinal compounds from their effluents before they are discharged into the environment. The objective of the present study was to employ the response surface model for the optimization of the removal of the pharmaceutical compound ciprofloxacin from aqueous media via the electrochemical coagulation process. In this study, a reactor containing two iron electrodes used as the anode and two titanium ones used as the cathode was employed to remove ciprofloxacin from municipal effluents. The electrodes were connected in a monopolar fashion to a DC power supply. Parameters such as pH (4‒8), current (0.5‒1.5 A), initial ciprofloxacin concentration (15‒40 mg/L), and reaction time (15‒30 min) were introduced into the Design Expert software as the main design parameters. FT-IR analysis was conducted and SEM images were prepared while COD removal and changes in UV-VIS spectrum were determined under optimum conditions. Process modeling was accomplished using the response surface methodology (RSM) which is a statistical model for process optimization drawing upon central composite design (CCD). Modeling results showed that process efficiency was affected by the above parameters and that the optimum conditions for a process efficiency of 85.91% at an initial CIP concentration of 15mg/L would include pH=7.68, a current of 1.5 A, and a reaction time of 30 min. Under these conditions, COD removal efficiency would be 64%. FT-IR analysis and SEM images indicated changes during the process. Wavelength scanning also indicated reducing concentration of the contaminant due to mineralization. The results of the study indicate that optimization by RSM reduces the number of tests required and enhances their accuracy. It was also found that electrocoagulation has a high CIP and COD removal efficiency which makes it capable of being successfully exploited for the removal of organic pollutants from effluents before their discharge into the environment

Access to safe drinking water is an important means of safeguarding public health. This cross-sectional study was designed to investigate the performance of electrocoagulation in the treatment of surface waters. For this purpose, water samples were taken from the intake to the Soleymanshah-Songhor Dam. Treatment was carried out in a reactor operating in the batch mode. Experiment runs were designed using the Design Expert Software (Stat-Ease Inc., Version 6.0.6) to investigate the effects of voltage (5-25), reaction time (20-60), temperature (10-30Ċ), and rapid mixing (200-400) on the Mn (II), Fe (II), hardness, alkalinity, and turbidity removal efficiencies as a result of treatment with aluminum electrodes. After the treatment process, the study parameters and the dissolved metal content due to the dissolution of the anode electrode were measured. Maximum removal efficiencies for Fe (II), Mn (II), hardness, and alkalinity were 96.2%, 94.6%, 26.6%, and 12.2%, respectively, while turbidity reduced from 0.6 to 0.15 NTU. Moreover, the dissolved Al content in the treated sample was found to be higher than the standard limit allowed for drinking water. Thus, the electrocoagulation process seems to be effective in the removal of the investigated contaminants from surface waters. However, the factor limiting the use of this method under maximum efficiency conditions is the dissolved metal content due to the dissolution of the anode electrode, which is a significant concern for the public health. In contrast, the electrocoagulation process seems to be an efficient and safe pretreatment method using aluminum electrodes if operated for achieving optimum efficiencies.

The electrochemical oxidation process was used for the degradation of Acid Brown 14 in both bench and pilot scale reactors. The bench scale one with a working volume of 0.5 L was equipped with platinum plate used as the anode and stainless steel (SS-304) plates as the cathode. The pilot scale reactor had a volume of 9 L and was equipped with SS-304 plates used as both the anode and the cathode. Experiments were run using these reactors to investigate the two parameters of energy consumption and anode efficiency. The bench scale reactor was capable of removing 92% and 36% of the dye and COD, respectively, after 18 min of operation. The pilot scale reactor, however, was capable of removing 87% and 59% of the dye and the COD content, respectively, after 60 min of operation. The kinetic study of both the bench and pilot reactors for dye and COD removals showed that both processes followed a zero order kinetic.

Electrocoagulation is an electrochemical method for the treatment of water and wastewater. The present cross-sectional study was designed to investigate the removal efficiency of total coliform and heterotrophic bacteria from surface water using the process. For this purpose، water samples were taken from the drinking water intake at Suleiman-Shahsonghur Dam. The electrocoagulation process was carried out in a Plexiglas reactor in the batch mode with Al and Fe used electrodes. The experiment design was carried out using the Design Expert Software (Stat-Ease Inc.، Ver. 6. 0. 6). After each run، the values of metals dissolved due to anode electrode dissolution were measured using the Inductively Coupled Plasma (ICP) and the results were analyzed using the RSM model. Results revealed maximum removal efficiencies of 100% and 89. 1% for total coliform and heterotrophic bacteria using the Al electrode، respectively. Also، maximum removal efficiencies using the Fe electrode for the same pollutants were 100% and 76. 1%. The measurements clearly indicate that the quantities of Al and Fe released in water were higher than the recommended values. While the electrocoagulation process showed to be effective in removing microbial agents from surface waters، the high concentrations of dissolved metals due to the dissolution of the anode electrode seem to remain a health problem that requires optimal conditions to be determined for acheiving standard concentrations of the dissolved metals.

Dyes due to coloring nature are appearance pollutants and destroys the transparency and aesthetic quality of surface waters even at relatively low concentration. Several processes have been used for dye removal from wastewater. In recent years، electrochemical methods have been successfully employed to treat dying wastewater. In this study، the electrocoagulation method with aluminum electrodes were used for polyacrylic textile wastewater treatment. COD of wastewater was 1400mg/l. This study was conducted in laboratory scale. The sample was placed in to the electrochemical reactor contains 4 electrodes. The electrodes were connected to a DC power supply. Then the effect of the three operational parameters، electrolysis time (20-60 minutes)، electrical applied current (0. 5-2. 5 Ampere) and pH (4-9) on color and COD removal efficiency has been investigated. The results showed that the color and COD removal efficiency is a direct relation with increasing of the reaction time and inverse relation with increase of pH. Optimum operation conditions were in applied current of 1. 5 A، the retention time of 60 minutes and pH of 4. In this condition، color and COD removals were 86% and 85%، respectively. This study showed that electrocoagulation process is an effective and efficient method to treatment of polyacrylic textile wastewater.

Leachate of urban solid waste landfills is one of the most important of environmental concerns. Today, electro-coagulation is considered as a method for leachate treatment. In this process coagulants are produced during metallic electrode dissolution. In this article, treatability of old leachate of Kahrizak landfill of Tehran by electro-coagulation method was studied. The study was done in laboratory scale by using steel electrodes grades ST-12, ST-37, and CK-45 and measuring COD, SS and ORP parameters. COD removal was obtained 42.66, 34.37 and 35.2 percent for ST-12, ST-37 and CK-45 electrodes while the operation time and current were 100 min and 7.2 A for initial COD concentration of 160,000 mg/l. COD removal increased 6.78, 4.38 and 12.12 percent when the operation time increased to 140 min, respectively. As well, COD removal was increased 38.98, 22.64 and 25.38 percent and SS removal was enhanced 16.4, 19.79 and 18.71 percent for ST-12, ST-37 and CK-45 electrodes, while the current density increased from 33.33 to 66.166 A/m2. The results also showed ST-12 electrode had the best efficiency for leachate treatment with COD and SS removal of 64.67% and 98.79% respectively while the current density was 66.166 A/m2 equals charge’s loading of 46.155 F/m3.

Electrocoagulation is one of the technologies which have been considered by many researchers in recent years. This process has many advantages including high efficiency, no need to chemical addition, low sludge production, capability of process control, easy to operation and maintenance. Bipolar electrodes system is one of the electrocoagulation techniques which can be used for increasing the process efficiency and better distribution of the electric current. The aim of this study was to remove hexavalent chromium from aqueous solution by electrocoagulation technique. Response surface methodology (RSM) was used to optimize the parameters involving in the process, and the effect of current density, initial chromium concentration and pH on the process were investigated. At optimal conditions, for the highest chromium removal (>90%), the optimum initial chromium, reaction time, current density and pH were found to be 117 mg/L, 50 min, 11.75 mA cm-2 and 4.5, respectively. It can be stated that electrocoagulation is an efficient technique for separation and removing high chromium concentration from aqueous solutions.

Electrocoagulation (EC) and Electrocoagulation/flotation (ECF) processes are simple and efficient in water and wastewater treatment. In recent years, many investigations have focused on the use of these processes for treating of polluted water. The purpose of this study was to investigate the efficiency of EC and ECF processes in removal of high turbidity water using different electrodes in different circumstances. In present study an electrocoagulation and electrocoagulation/ flotation reactor in a lab scale to an approximate volume of 6 liters which is equipped with four Al-AL and Fe-Fe electrodes (200 * 20 * 2 mm) was used for removing of highturbidity water. The effects of operating parameters such as type of electrodes, initial water turbidity, applied voltage (10 to 30 v), initial pH of the solution (3 to 12) and reaction times (5 to 30 minutes) were evaluated. The batch experimental results showed that initial turbidity water, initial pH of the solution, different applied voltagesup to %88 turbidity as initial turbidity of 1200 NTU have been removed when using Al-Al and Fe-Fe electrodes and reaction times highly effective on the turbidity removal efficiency in these processes. In ECF process, 84%in optimum condition. However, in EC process the maximum removal was found up to 68% of initial turbidity when using Al-Al and Fe-Fe electrodes in same operation. Based on the result obtained in this study, the type of electrodes in EC and ECF processes significantly affect the removal rate of high turbid water. Also, it was found that much higher turbidity removal could be achieved by ECF process than that by EC process in the same condition.

There are many non-wood lignocelluloses resources such as wheat, rice straw and other agriculture by- products with appropriate feature for pulp production in Iran. The most major deterrent to their use is presence of pulping black liquor that due to lignin of lignocelluloses solution contains significant amounts of color and phenol compounds. The aim of this paper was investigation of the ability to remove phenol and color as the most important organic pollutants from back liquor of agri-based pulping process using electrocoagulation method. In the electrocoagulation process aluminium electrode was used and cell potential and current intensity were adjusted on 16 V and 1700 mA respectively. The effect of various treatment time (10, 25, 40, 55, 70 min) and initial pH (3, 5, 7, 9, 10/5) of black liquor were investigated.The results showed that maximum of decrease obtained at pH 5 that has led to a remove capacity 78% of phenol and 98% of color in treatment time 70 min. electrocoagulation method can be used for black liquor treatment because of simple, effective and its low investment cost compared to other technologies.

The presence of toxic heavy metals in industrial wastewaters and its discharge into the sewage system is one of the most environmental problems. In this research, electrocoagulation method was used to remove cadmium as a toxic heavy metal from aqueous phase. The important parameters wich affect the removal of cadmium from wastewater such as the electrode type, area of the electrode, distance between electrodes, voltage, intial concentreation of cadmium and the pH were examined. Six electrodes with aluminum and iron types were employed with the areas of 2352, 3360, 4200 cm2. The distance between electrodes were chosen to be 1, 2, 3 cm, respectively. The experimental results indicated that optimum condition was obtained with high surface area of the electrodes of 4200, distance of 1cm, entrance power of 185, residence of time of 40 minutes and pH of enfluent of 10.25. Results showed that change in initial cadmium concentration reduced its removel.