Electrocoagulation Unit Research Articles

Experimental electro coagulation unit for pretreament of mains water for dteam generation at thermal power plants

The article covers the state of pre-chemical treatment of natural water at Tashtpp with the use of aluminum sulphate and the creation of an experimental unit for producing coagulant, aluminum sulphate, as well as a block diagram of the proposed electrocoagulation unit for pre-treatment and clarification of water. An electrocoagulation technology for pre-treatment and clarification of water for Tashtpp steam boilers has been developed.

Design of Table Top Electrocoagulation Unit for Remediation of Wastewater from Paper Industry

Design of Table Top Electrocoagulation Unit for Remediation of Wastewater from Paper Industry

Downstream Processing of Palm Oil Mill Effluent in a CBME Reactor

AbstractThis study describes a laboratory-scale continuous-flow bipolar mode electrocoagulation (CBME) unit that was developed as a downstream process unit for polishing an anaerobically treated pa...

Marigold wastewater treatment in a lab-scale and a field-scale continuous bipolar-mode electrocoagulation system

Abstract Agro-industrial wastewaters are generated in large volumes with high organic content. It is very difficult to eliminate the recalcitrant organic compounds present in the wastewater after the biological treatment. Monopolar-mode electrocoagulation systems are extensively studied in the literature as polishing treatment systems after the biological treatment. However, studies on bipolar-mode electrocoagulation systems are limited. This study compares the performance of a Continuous Bipolar-Mode Electrocoagulation (CBME) unit developed at a laboratory scale with that of a field-scale CBME system used for the removal of recalcitrant organic carbon and phosphorus from marigold wastewater. The design parameters required for a CBME system were extracted. The higher Surface area to Volume (S/V) ratio of 76.5 m-1, used in this study achieves higher treatment efficiency at lower energy consumption and lesser retention time, which saves energy and space when applied in field scale. The optimization study was carried out at both lab-scale and field-scale for the removal of Total Organic Carbon (TOC) and Total Phosphorus (TP) using Response Surface Methodology (RSM). The S/V ratio was kept constant, for both the CBME systems. The potential design parameters and the performance of the CBME reactors were compared. The optimum values obtained for operating variables were found to be, pH at 6.5, retention time of 6.8 min and current at 2.9 A for lab-scale system and the optimum values obtained for field-scale system were found to be, the retention time of 6.5 min and current at 51.3 A. The organic compounds were identified in the wastewater samples at the optimum points. Retention time, S/V ratio, and energy consumption were found to be potential design parameters for a CBME system.

A hybrid system for groundwater denitrification using electrocoagulation and adsorption

The treatment of nitrate-contaminated groundwater was studied using a hybrid system comprising an electrocoagulation unit and a zeolite adsorption reactor. In the electrocoagulation (EC) process, aluminum alloy electrodes were used in an undivided cell. Experiments in the laboratory-scale reactor were carried out in unregulated temperature conditions to treat synthetic groundwater solutions containing initial nitrate concentrations of 10–100 mg NO3−-N·L−1 in batch mode and without using additional pH buffers. Various operating variables, such as applied current density (about 20 mA cm−2 to 80 mA cm−2), concentration of NaCl electrolyte (0.0–1.0 g L−1) and treatment time (up to 120 min), were tested for their effects on nitrate removal. Results showed that initial NO3−-N concentration, current density and electrolyte concentration, play important roles in EC. For all initial NO3−-N concentrations and current densities tested, the highest NO3−-N removal rates (up to 2.374 g L−1·d−1) were achieved without additional electrolyte and/or with the lowest electrolyte concentration of 0.1 g L−1. In these experiments, EC reduced NO3−-N to below the standard limit of 10 mg L−1 after 10–60 min of electrolysis. A significant quantity of by-products, ammonium and dissolved aluminum, formed during the process, however these were successfully removed by zeolite adsorption in the post-treatment step. The electrochemical reactor using the specific anode/cathode combination and an environmentally-friendly post-treatment step such as zeolite adsorption, can be used to efficiently remove nitrate from groundwaters because of its high efficiency.

Mixed Herbal Oil Processing Factory Wastewater Treatment by Pilot-scale Electrocoagulation Unit: Cost Analysis

Mixed Herbal Oil Processing Factory Wastewater Treatment by Pilot-scale Electrocoagulation Unit: Cost Analysis

Application of waste water treatment technology from exhaust electroplating and anodizing process using electro-coagulation method

Production process in vehicle exhaust small industry releases waste water from xhaust tube electroplating and anodizing without any pre-treatment. It contains plating and coloring from Chroom hexavalent as much as 65,586 mg/l and lead 86,576 mg/l, which is more that the electroplated and anodized waste water quality limit of and 0,3 mg/l 0.1 mg/l for Lead concentration. In addition Chroom and Lead is categorized as toxic and dangerous waste substances. This research is aimed at studying the fundamental characteristics of Chroom and Lead separated from electroplated waste water in exhaust tube by means of electro-Coagulation. To get a comprehensive understanding of process characteristics, two intrinsic parameters are the focus of this research. This include electro-chemistry (installed voltage and current gain) and psycho-chemistry-fluid (process time and contaminant concentration). The research method involved designing assembly and fabrication of an electro-coagulation unit in the laboratory scale. It also a characteristic study of separation process by varying both electrochemistry and psycho-chemistry-fluid parameters, whilst developing a characteristic model of Chroom and lead separation. Those research stages provided measured contributions that resulted in a prototype of a compact and modular electrocoagulation device. This was designed with 5 pairs of aluminum electrodes that capable of separating chroom and lead with a gain of 88,76% and 87.54%.

Integrated Electrocoagulation and Tight Ultrafiltration Membrane for Wastewater Reclamation and Reuse

Wastewater reclamation and reuse have become an alternative to saving operational costs while reducing the impact of waste pollution. In this paper, integration of electrocoagulation (EC) and polysulfone-based ultrafiltration (UF-PSf) membranes were used for the mentioned purpose. The EC unit equipped with 7 (seven) pieces of E-shaped of Al electrodes, which operated at a current of 3 (three) Amperes and a residence time of 2 (two) hours. The waste samples obtained from textile and oil palm industries. The experimental results were compared based on product quality and economic feasibility. When used for textile waste treatment, the integrated EC-UF units reduced TDS, TSS, BOD, and COD by 77%, 95%, 70 -80%, and 60-70%, respectively. While in palm oil waste treatment, the TDS and TSS reduced by 92% and 98%. The electrode loss rate in palm oil waste treatment was 2 (two) times greater than textile waste. By assuming that the waste production capacity of both industries was 400 m3/day, the water production cost in textile waste treatment was Rp. 4,000/m3. While in the palm oil waste treatment, the water production cost was Rp. 6,000/m3. These results showed that the EC-UF unit could be used as an economical and environmentally friendly alternative process for reclamation of industrial wastewater that meets the clean water quality standards.Keywords: electrocoagulation, industrial wastewater, ultrafiltration, reclamation, reuse water

Application of electrocoagulation: issues with community-level defluoridation

Fluoride contamination in groundwater causes major health problem due to fluorosis (skeletal and dental). This study focused on the development of an electrocoagulation-assisted fluoride removal system where activated alumina can be used as a downstream polishing unit for additional removal of fluoride. Laboratory experiments showed rapid and effective removal of fluoride at about 200 C/l of electro-charge loading from contaminated water with 2.1 mg/l of fluoride. Nalagola village of West Bengal in India, where most of the available drinking water sources were contaminated with excess fluoride, was selected for the installation of the defluoridation unit. The electrocoagulation unit along with the downstream sand filter was able to decrease the fluoride level below 1.0 mg/l, and therefore, the activated alumina column was kept as standby. However, in case the electrocoagulation system malfunctions due to passivation or disruption of power supply, the alumina column will be put to use to treat the water to the desired extent. Higher fluoride content in the contaminated water will, however, require the downstream alumina column as the polishing unit for adequate removal of fluoride. It was observed that deposits of aluminum and calcium oxides/hydroxides on the electrode surfaces caused passivation of the electrodes and regular reversal of polarity helped to avoid passivation to a large extent. The community-based defluoridation unit of capacity 600 l/h is serving about 320 families. The water committee formed by the beneficiaries are collecting water tariff from each family, and the fund is helping in operation of the filter for the last 33 months.

Electrocoagulation for the purification of highly concentrated brine produced from reverse osmosis desalination of coal seam gas associated water

The ability of electrocoagulation (EC) at facilitating salt recovery from brine resultant from reverse osmosis (RO) desalination of coal seam gas (CSG) associated water is described. The aim was to reduce the presence of high concentrations of dissolved silicate which inhibit salt recrystallization by forming precipitates on equipment. The hypothesis was that EC could operate effectively in brine solutions and provide high silicate removal; thus facilitating a zero liquid discharge strategy. A benchtop EC unit equipped with either aluminium, iron or mixed iron-aluminium electrodes was used to treat simulated brine from a high recovery RO process. Up to 98.9% of silica was removed when aluminium or aluminium-iron electrodes were used. Significant reduction in concentrations of alkaline earth ions were also recorded (Ba > Sr > Ca > Mg) especially with iron electrodes. It appeared that silicate removal was via aluminosilicate formation. Hydraulic retention time was a key variable with 20 s recommended on the basis of performance/cost trade-off. Polarity reversal did not substantially change removal performance but impacted power consumption. For iron and iron-aluminium electrodes 1 min polarity reversal was preferred whereas for aluminium electrode 5 min was optimal. However, a thick coating was formed on the electrode surface and this may inhibit performance if longer tests are conducted. All flocs formed settled relatively rapidly (<20 min) which was in a time frame suitable for industrial application.

Application of a Continuous Bipolar Mode Electrocoagulation (CBME) system for polishing distillery wastewater

A continuous bipolar mode electrocoagulation (CBME) unit was used in this study for polishing a biologically treated distillery wastewater at laboratory scale. This study focuses on optimizing the process for removal of Total Organic Carbon (TOC) from an anaerobically-treated distillery wastewater. Response surface methodology (RSM) was used for optimizing the process. The study was conducted by varying three operating parameters: Initial pH (2-10), reaction time (0.5-15 min), and current density (13-40 A/sqm). High R-square values, above 0.9, were obtained with ANOVA. Optimal point was observed to be at pH-6.04, Reaction time-11.63 min, current density-39.2 A/sqm. Experimental values of TOC removal at optimal point were found to be 73% against maximum predicted value of 79%. Color removal efficiency was observed to be 85% at the optimal points. It can be concluded that CBME system can be a suitable alternative for removal of recalcitrant carbon and color post-biological treatment in distillery wastewaters.

A comparative optimization and performance analysis of four different electrocoagulation-flotation processes for humic acid removal from aqueous solutions

Abstract Humic substances (HSs) are a group of complex macromolecular polymeric compounds originating from the decomposition of plant residuals and other organic matter. Within the presence of micro-pollutants and heavy metals, HSs negatively act upon potable water quality by contributing to aesthetic problems such as yellowish or brownish color and annoying taste and odor. They are also responsible for re-growth of pathogenic microorganisms and fouling of membranes in water distribution systems. More importantly, these high-molecular-weight polymers have been noted to be the major contributor to the formation of disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). Considering these harmful effects, removal of HSs is one of the significant tasks in drinking water treatment. For this purpose, this study aimed to explore the effects of various operating parameters (initial concentration, initial pH, electrical conductivity, pulse time, pulse number, and process time) on the humic acid (HA) removal efficiency and energy consumption. In this study, a new current supply method called alternating pulse current electrocoagulation-flotation (APC-ECF) process was proposed, and a detailed comparative optimization of four different ECF processes (direct current (DC)-simple electrode, DC-perforated electrode, pulse current-simple electrode, and pulse current-perforated electrode) was conducted within the framework of Taguchi-based experimental design methodology. According to scanning electron microscopy (SEM), the morphology of electrode surfaces with APC and perforated electrode showed less disordered (irregular) pores and a regular structure of aluminum compared to the DC, which confirmed the difference in the corrosion rates. Moreover, the proposed APC-ECF method led to the production of less dewatered and dense sludge. The results of the performance analysis revealed that the APC with a perforated electrode provided 3.2-fold lower energy consumption and 2.5-fold lower aluminum consumption compared to the DC with a simple electrode. Considering the expenses associated with power consumption and sludge disposal costs for the electrocoagulation unit, the experimental findings corroborated that the proposed APC-ECF process could be used as a promising and cost-effective technology in water treatment for the removal of HSs.

Improved oil removal ability by the integrated electrocoagulation (EC)-carbon membrane coupling with electrochemical anodic oxidation (CM/EAO) system

A novel electrocoagulation (EC)-carbon membrane coupling with electrochemical anodic oxidation (CM/EAO) integrated system was designed and constructed for oily wastewater treatment. Electrocoagulation was adopted as a primary unit, and the effects of many parameters, including current density, electrolyte concentration, initial pH, feed oil concentration, and operating time on pretreatment performance were investigated and optimized. Subsequently, CM/EAO was set as a secondary unit for further deep purification of the EC effluent. The results showed the integrated system had great potential for oil removal from wastewater. The EC unit could remove nearly half of COD and TOC in the feed, and the following CM/EAO unit further degraded the EC effluent, and the COD, and TOC were reduced to 13 mg/L and 22 mg/L, respectively. The mechanisms involved in each stage were proposed. A large proportion of oil droplets in oily wastewater were firstly removed by electrocoagulation process, and the remaining oil droplets were further decomposed into small molecules or even into CO2 and H2O by hydroxyl radicals generated from electrochemical anode oxidation reactions. The degraded intermediate products including various n-alkanes and polycyclic aromatic hydrocarbons were identified by GCMS.

Turbidity and oil removal from oilfield produced water, middle oil company by electrocoagulation technique

Huge quantity of produced water is salty water trapped in the oil wells rock and brought up along with oil or gas during production. It usually contains hydrocarbons as oil and suspended solids or turbidity. Therefore the aim of this study is to treat produced water before being discharge to surface water or re injected in oil wells. In this paper experimental results were investigated on treating produced water (which is obtained from Middle Oil Company-Iraq), through electrocoagulation (EC). The performance of EC was investigated for reduction of turbidity and oil content up to allowable limit. Effect of different parameters were studied; (pH, current density, distance between two electrodes, and electrolysis time). The experimental runs carried out by an electrocoagulation unit was assembled and installed in the lab and the reactor was made of a material Perspex, with a capacity of approximately 2.5 liters and dimensions were 20 cm in length, 14 cm in width and 16 cm height. The electrodes employed were made of commercial materials. The anode was a perforated aluminum rectangular plate with a thickness of 1.72 mm, a height of 60 mm and length of 140 mm and the cathode was a mesh iron. The current was used in the unit with different densities to test the turbidity removing efficiency (0.0025, 0.00633, 0.01266 and 0.0253 A/cm2).The experiment showed that the best turbidity removing was (10, 9.7, 9.2, 18 NTU) respectively. The distance between the electrodes of the unit was 3cm. The present turbidity removing was 92.33%. A slight improvement of turbidity removing was shown when the distance between the electrodes was changed from 0.5 to 3 cm with fixation of current density. The best turbidity removing was 93.5% , (7.79 NTU) when the distance between the electrodes were 1 cm. The experimental results found that concentration of oil had decreased to (10.7, 11.2, 11.7, 12.3) mg/l when different current densities (0.00253, 0.00633, 0.01266, 0.0253) A/cm2 were used, respectively with the distance between the electrodes was 3 cm. The best result of oil content decreasing was 10.7 mg/l with current density 0.0253 A/cm2. These results are within allowable limit to provide the possibility of reuse the water and can be injected in oil wells

Coagulation-flocculation treatment of white pepper (&lt;i&gt;Piper nigrum L.&lt;/i&gt;) processing wastewater

Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and hydrolyzable tannins that results dark tan/brown colour effluent which cannot be discharged to the environment without proper treatment. Therefore, these experiments were conducted to investigate the effectiveness of electro-coagulation using aluminum (Al) electrodes and coagulation-flocculation with Alum [Al2(SO4)3.18H2O] in reducing the strength of pepper soaked effluent. A laboratory scale electro-coagulation unit was made using two aluminium plates (9 cm × 5 cm × 0.3 cm) as electrodes leaving a 0.5 cm gap between plates and powered with a 12 V DC power supply through a resistance box which is used to regulate the current density. The current density could be controlled between 0-1 A. Coagulation flocculation with Alum was tested at five doses; 1 to 5 g/L with 1 g increments at laboratory scale. The effluent colour was measured using a spectrophotometer at a wave length of 600 nm. According to the results, removal efficiencies of colour, Turbidity and COD were 94%, 91% and 89%, respectively for 20 minutes of electro-coagulation and 92%, 90% and 92%, respectively with 3 g/L Alum treatment. The pH of the effluent during electro-coagulation for 20 minutes increased to 9.0 while Alum treatment with 3g/L reduced to 5. When treated effluent filtered through a fine sand filter, Total Dissolved Solids (TDS), Electrical Conductivity (EC) and COD could be reduced further and reached the standard values to discharge in to the environment as irrigation water.

Effect of some effective parameters on COD Removal from Nam Son Landfill Leachate by electrocoagulation

Leachate becomes ahead of wastewaters as being the most difficult to treat due to its complex and widely variable composition. In this research, the leachate treatment performance by electrocoagulation (EC) was studied. The samples of leachate were taken from Nam Son landfill in Hanoi. The effects of factors namely current intensity, electrolysis time, initial pH and anode materials on the EC performance were investigated via chemical oxygen demand (COD) removal efficiencies. The input leachate properties were obtained as COD, NH4+ and pH in the range of around 6247 ± 295, 1270 ± 38 mg/l and 8 ± 0.1, respectively. Mono-polar electrocoagulation unit was carried out in a batch system for leachate treatment with iron electrodes and approximately 1.8 litter of leachate. Firstly, with the increase in current (1 to 4A), the COD removal efficiencies increased from 50.00 to 78.57% (pH = 8 and operating time = 40 min). Secondly, by the increase in operating time, the treatment performance also went up significantly in first 40 min, then nearly level-off at above 73 % (pH=8, current intensity = 3A). In addition, the effect of pH in range of 5 to 10 on the electrocoagulation process was studied and showed the highest treatment efficiencies in neutral and mild alkaline medium, especially between 6 &lt; pH &lt; 8. Finally, the electrode materials made of iron and aluminum was investigated and the result indicated that when the iron anodes were replaced by aluminum, the COD removal efficiency experienced a considerable decline, from 70 to 37.93% (pH = 8 and operating time = 40 min). In combination of all experiments, the optimum operating conditions were achieved as iron electrodes, current intensity of 3A, electrolysis time of 40 min, the raw pH with iron electrodes, resulting the maximum COD removal efficiencies of 73.21%. As a result, the electrocoagulation can be applied to leachate pre-treatment.

Experimental study on electrocoagulation of textile wastewater by continuous horizontal flow through aluminum baffles

We investigated the feasibility of applying a continuous textile wastewater (TWW) treatment, which was accomplished by using electrocoagulation (EC) unit with zigzag horizontal flow across a series of mono-polar aluminum plate baffles. The effects of operating parameters such as current density (20-80 A/m2) and detention time (5-40 min) on turbidity, color, chemical oxygen demand (COD), total suspended solids (TSS) and total dissolved solids (TDS) removal were studied. The optimum conditions were determined as 60 A/m2 and 20min by monitoring zeta potential (ζ) of effluent. At the optimum conditions, removal efficiencies for turbidity (97.63%), color (87.87%), COD (93.3%), TSS (94.02%), and TDS (52.13%) were observed. Further, addition of 4mg/L of NaCl dose in the TWW modified conductivity suitably, thereby reducing electrical energy consumption per cubic meter of waste water and specific electrical energy consumption (SEEC) from 13.33 to 2.67kWh/m3, and 23.84 to 4.77kWh/kg Al, respectively. Comparing the EC with conventional coagulation process, EC showed better pollutant removal efficiency.

Petroleum refinery wastewater treatment: A pilot scale study

A three-step pilot plant was designed, fabricated and tested for the treatment of highly contaminated petroleum refinery wastewater. The three-step process consisted of an electrocoagulation (EC) unit, a biological treatment in a spouted bed bioreactor (SBBR) using immobilized Pseudomonas putida in PVA particles, and an adsorption process using granular activated carbon in a packed column. The pilot plant was operated for a period of ten months at a flow rate of 1m3/h, with continuous runs lasting up to 12h. Different arrangements of the three units were tested to determine the most effective sequence. Placing the EC unit as the pretreatment step resulted in the best performance, since it reduced the COD and suspended solids, and consequently enhanced the performance of the succeeding biodegradation and adsorption units. At the optimum conditions and unit arrangement, the pilot plant was able to reduce the COD by 96% and the concentrations of phenol and cresols by nearly 100%.

Self-powered electro-coagulation system driven by a wind energy harvesting triboelectric nanogenerator for decentralized water treatment

Many decentralized communities like rural communities of developing countries and remote communities, suffer from a scarcity of adequate water treatment because there is insufficient capital to construct relevant facilities, no experts to handle the required chemicals, insufficient electricity to operate them. Herein, we report a fully self-powered electro-coagulation (SPEC) system for de-centralized water treatment. For this, a triboelectric nanogenerator harvests ambient wind energy to provide the needed power. A simple electro-coagulation unit, composed of a simple pair of electrodes, successfully removes dissolved colloidal pollutants from water, while coagulating and precipitating pollutants, without any use of chemicals or an external power supply. The SPEC system removes 90% of algae and 97% of organic dye with self-powered treatment for 72h. Due to its easy operation, and its low cost arising from its inherently simple structure, requirement for much smaller-scale facilities and low operating cost, the SPEC system could become a powerful candidate for appropriate water treatment in many regions lacking centralized water treatment.

Removal of Six Estrogenic Endocrine-Disrupting Compounds (EDCs) from Municipal Wastewater Using Aluminum Electrocoagulation

Conventional wastewater treatment plant (WWTP) processes are primarily designed to reduce the amount of organic matter, pathogens, and nutrients from the incoming influent. However, these processes are not as effective in reducing the concentrations of micropollutants, including endocrine-disrupting compounds (EDCs), which notoriously evade traditional wastewater treatment technologies and are found even in tertiary-treated effluent. For WWTPs practicing deep-well injection or surface-water discharge, EDCs in the treated effluent are discharged into groundwater or the aquatic environment where humans and wildlife may potentially suffer the effects of chemical exposure. In the current laboratory-scale study, we tested a bench-top electrocoagulation (EC) unit utilizing aluminum blades for the removal of six estrogenic EDCs [estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), bisphenol-A (BPA), and nonylphenol (NP)]. Samples of municipal wastewater influent and tertiary-treated effluent were spiked with the six EDCs in order to test the removal efficiency of the EC unit. The mean concentration of each EDC component was statistically lower after EC treatment (removal range = 42%–98%). To our knowledge, this is the first study to investigate aluminum electrocoagulation for removal of these specific EDCs, including nonylphenol (without the ethoxylate chain), as well as natural and synthetic estrogens.