Conventional Electrocoagulation Research Articles

A solar-powered electrocoagulation process with a novel CNT/silver nanowire coated basalt fabric cathode for effective oil/water separation: From fundamentals to application.

Electrocoagulation (EC) has proven its high efficiency and environmental sustainability for treating several types of wastewaters. However, the primary drawbacks of the conventional EC process are the suitable electrode materials and the relatively high cost due to the requirement for electric energy. To overcome these practical challenges, this study investigated effective oil/water separation by a solar-powered electrocoagulation (SPEC) process using a novel highly conductive basalt fabric (BF) cathode. The BF cathode was fabricated using a simple approach: dip-coating in carbon nanotubes (CNT) dispersion, followed by a bath exhaustion coating in a silver nanowires (AgNws) solution, and its successful preparation was confirmed through several advanced characterization techniques. The effect of the CNT-AgNws coating on the electrical conductivity of the BF-CNT/AgNws was investigated using the four-probe tester. The BF-CNT/AgNws cathode exhibited a high conductivity of 1.66×104S/m, which indicates its applicability in the SPEC system. Under the operating conditions of applied voltage (25V), SPEC time (30min), stirring rate (150rpm), and NaCl concentration (1g/L), the experiment's results showed a high COD removal of 90.2±0.03 %, a low energy consumption of 1.28±0.01 kWh/kgCOD, and electrode consumption of 0.35±0.06kg/m3. In addition, due to the use of solar-powered energy, the overall cost was reduced by eliminating the electricity fees. Moreover, the reusability test results proved that the BF cathode has potential reusability in successive SPEC experiments while maintaining its performance. In conclusion, the obtained findings are very encouraging in designing novel EC cathodes for effective oily wastewater treatment at an industrial scale.

Electrolysis-enhanced coagulation process for highly emulsified oily wastewater treatment: Floc diameter, oil removal performance and mechanism

Electrocoagulation (EC) is one of the most effective processes for highly emulsified oily wastewater (HEOW) treatment. However, the demulsification efficiency depends on the amount of aluminum or iron ions released from the conventional sacrificial metal anode, leading to challenges such as rapid anode dissolution and short lifespan. To address these issues, this study presents a novel electrolysis-enhanced coagulation (EEC) process, replacing conventional Al electrodes with dimensionally stable titanium anodes coated with ruthenium-iridium oxide and supplementing the electrochemically released Al³+ with externally added AlCl3.This process was assessed using the Turbiscan LAB Expert to measure the variation in floc diameter under various electrolysis times, AlCl3 concentrations, and current densities. At a current density of 5 mA/cm2 and AlCl3 dosage of 50 mg/L, the mean floc diameter increased from 32.4 ± 1.7 µm to 630.3 ± 76.9 µm as the electrolysis time extended from 0 to 4 min. Under optimal conditions, the oil removal efficiency of 96.7%±0.2% and residual oil concentration in the effluent of 66.3 ± 3.5 mg/L were achieved. The energy consumption of this process was 0.17 kWh/m³, which was a relatively low value compared with conventional EC techniques. Moreover, as electrolysis time increased, a greater proportion of dissolved and suspended Al transformed into species incorporated within the floating oil. These findings demonstrate the potential of the EEC process to replace EC in treating HEOW, providing an effective and durable solution.

Influence of interelectrode distances in electrocoagulation: is there any possibility and advantages to operate at micro-distances with low-conductivity effluents?

It has been proposed for the first time to investigate the possibility to implement micro-inter-electrode distances in electrocoagulation (EC) in order to improve both the treatment and energy efficiencies compared to conventional EC cells with centimetric distances. The study has been performed in a microfluidic monopolar flow-by filter-press cell for the treatment of simulated and real low-conductivity (0.5–1 mS cm−1) laundry wastewaters. The influences of interelectrode distance (delec) (100–10,000 μm), applied current density (japp) (10–200 mA cm−2), and types of anode materials (iron, aluminium and stainless steel) have been studied. The removal of representative organic pollutant (i.e., paracetamol at 15 mg L−1) as well as of total organic carbon (TOC) content (312 mg-C L−1) from actual wastewater was noticed, including at micro-distances. Optimal treatment capacities were obtained with delec of 0.5 mm (57% TOC removed), 3 mm (58% TOC removed) and 10 mm (41% TOC removed) and with japp of 70 mA cm−2, 40 mA cm−2 and 20 mA cm−2 respectively, using stainless steel anode. It led to reduced energy requirement at micro-distances (16 kWh g-TOC−1 at 500 μm) compared to millimetric gap (19 kWh g-TOC−1 at 3 mm, 40 kWh g-TOC−1 at 10 mm). Contrastingly, more sludge was generated with micrometric distance (172 g-sludge g-TOC−1 at 500 μm) compared to larger gaps (95 g-sludge g-TOC−1 at 3 mm, 87 g-sludge g-TOC−1 at 10 mm) due to higher optimal japp at low distances. The efficiency was maximal with an aluminium electrode, but this anode remained inapplicable with micro-distances using the current reactor design, given the high sludge production between the cathode and anode.

Effect of ozonation and UV-LED combination on simultaneous removal of toxic elements during electrocoagulation.

Cyanide and heavy metals pose significant risks as contaminants in certain industrial effluents. This study aims to concurrently eliminate cyanide and specific heavy metals from synthetic wastewater resembling gold processing effluent, employing an improved electrocoagulation method incorporating ozone and UV-LED. The investigation delves into the effects of pH, electrode type, current density, reaction time, and ozonation. The findings revealed notable removal efficiencies: 98% for cyanide, 76% for nickel, 85% for copper, and 84% for zinc when utilizing a stainless steel electrode as the cathode. Optimal removal rates were achieved at 94% for cyanide, 93% for copper, 92% for zinc, and 83% for nickel, employing the UV-LED-ozone technique with an ozonation flow rate of 4mg/s at pH = 10. Notably, when Al-Gr-SS-Fe electrodes and a current of 15mA/cm2 were applied, these removal efficiencies were observed. Therefore, the most favorable conditions for the concurrent removal of pollutants from synthetic wastewater involved maintaining a pH of 10, utilizing SS-Fe as anode and Al-Gr as cathode electrodes, and employing a current density of 15mA/cm2. The addition of ozonation with a flow rate of 4mg/s, along with UV-LED, further enhanced the removal process. In summary, it can be inferred that the enhanced electrocoagulation method outperformed conventional electrocoagulation, leading to increased elimination of cyanide and selected heavy metals.

Alternative treatment of olive mill wastewater by combined sulfate radical-based advanced electrocoagulation processes.

The aim of this study is to investigate the performance of advanced electrocoagulation (EC) process for the treatment of olive mill wastewater. In EC process, iron plates were used as electrodes, and peroxydisulfate (PS) and peroxymonosulfate (PMS) were added as oxidants. The effects of the initial pH value, current density, oxidant dose, and electrolysis time were optimized for pollutant removal from olive mill wastewater by EC-PS and EC-PMS processes. Control experiments showed that addition of oxidants to the conventional EC process increased the pollutant removal efficiency. Classical optimization method was used to determine optimum conditions, which were initial pH4, current density 40 mA/cm2 , oxidant dose 5g/L, and electrolysis time 30 min for both processes. Under these conditions, EC-PS and EC-PMS processes achieved 50.5% and 48.9% chemical oxygen demand (COD), 93.8% and 89.3% total phenol, 87.7% and 83% UV254 , and 74.5% and 64.1% total suspended solid removal efficiencies. Quenching experiments were performed to determine the dominant radical species participating in the processes. It was observed that hydroxyl and sulfate radicals were involved in both processes but hydroxyl radicals were more active. Specific energy consumption was calculated as 5.90 kWh/kg COD for EC process, 4.95 kWh/kg COD for EC-PS process, and 5.20 kWh/kg COD for EC-PMS process. The organic removal/sludge ratio of EC-PS process was found to be higher with 17.5g/L value. Although the application of EC-PS and EC-PMS processes alone is insufficient to meet the discharge limits, they have been found to be effective in olive mill wastewater treatment. PRACTITIONER POINTS: Peroxydisulfate (PS) and peroxymonosulfate (PMS)-based advanced electrocoagulation (EC) was used in olive mill wastewater treatment. 50.5% chemical oxygen demand (COD), 93.8% TP, 87.7% UV254 , and 74.5% TSS removals were achieved by EC-PS. 48.9% COD, 89.3% TP, 83% UV254 , and 64.1% TSS removals were obtained by EC-PMS. Hydroxyl and sulfate radicals were involved in both processes.

Cost cutting approach of distillery effluent treatment using solar photovoltaic cell driven electrocoagulation: Comparison with conventional electrocoagulation

This work is an attempt to treat rice grain-based distillery biodigester effluent (BDE) using photovoltaic (PV) cell driven electrocoagulation (EC) process. The BDE initially contain high chemical oxygen demand (COD) of 4252 mg/l and color of 456 PCU.PV cell-based EC reactors have been used to treat BDE with various electrode combination including FeFe, AlAl, FeAl, and AlFe etc. The effect of different operating parameters such as pH, current density (CD), electrode gap (g) and electrode combination on COD and color removal efficiency were investigated. Maximum COD and color removal efficiency of 94.9 % and 81.3 %, respectively were found at the optimum condition of pH 7, CD 24.9 mA/cm2, g 1.75 cm, electrolysis time (t) 60 min, electrode loss (Ec) 17.1 mg/land electrode combination of FeFe. A comparative study has been made by powering the EC system through conventional power supply and solar PV source and the PV oriented system was found better. Conventional power source required longer; t and needed slightly higher voltage while, PV system needed shorter t and low voltage to achieve nearly same pollution removal efficiency.

Simultaneous Removal of Cyanide and Heavy Metals Using Photoelectrocoagulation

One of the new methods used to remove the contaminants from effluent is the electrocoagulation method, which is sometimes combined with other methods to increase the removal efficiency of contaminants. To simultaneously remove nickel, cyanide, zinc, and copper, the combined method of photo-electrocoagulation was used along with an oxidizing agent, namely hydrogen peroxide (Hp). In addition, the effects of factors affecting the removal efficiency were studied, including pH, electrode arrangement, and current intensity. An electric current of 300 mA at a pH of 10 for 60 min, Fe-SS electrodes with a distance between them of 5 cm, and hydrogen peroxide at a rate of 4 mg/L were the ideal conditions needed to accomplish the photo-electrocoagulation-oxidation process. According to these study findings, when the combined method of photocatalyst-electrocoagulation-oxidation (Hp) was used, the highest removal efficiencies of nickel, cyanide, zinc, and copper were 85, 96, 94, and 98%, respectively. The results showed that using the combined photo-electrocoagulation-oxidation method increased the efficiency of simultaneous removal of pollutants by 10% compared to conventional electrocoagulation method. The reason for the increase in removal efficiency is the production of hydroxyl radicals simultaneously with the formation of coagulants produced by electrocoagulation process.

Treatment of Tannery Effluent Using Combined Electrocoagulation and Adsorbent of Powdered Marble

This paper discusses the ability to remove chromium and COD from a real chrome tanning wastewater by use of Electrocoagulation (EC) coupled with adsorption using Powdered Marble (PM) added to a batch stirred EC cell with a pair of duralumin electrodes. The effects of current density, adsorbent dose and contact time were studied. In comparison to the conventional EC process, the coupling of electrocoagulation and adsorption using powdered marble showed that the addition of an appropriate powdered marble improved the removal of Cr(III) and COD using lower current densities and a short contact time. Nearly 99% of Cr(III) and COD were removed from tanning effluent with an initial chromium concentration of 3.21 g/L and COD of 3.75 g/L. the results obtained showed better performance using combined electrocoagulation and adsorbent of powdered marble compared to the simple EC.

Refinery Wastewater Treatment by a Novel Three-Dimensional Electrocoagulation System Design

A novel three-dimensional electrocoagulation method was used in the current work to explore the treatment of refinery wastewater. Metal-Impregnated Granular Activated Carbon (MIGAC) was employed as a third particle electrode in the inventive design. A comprehensive investigation has been conducted to evaluate its performance. BET-specific surface area, total pore volume, X-ray Fluorescence (XRF), Energy-Dispersive X-ray spectroscopy (EDS), and Scanning Electron Microscopy (SEM) were employed for the characterization of MIGAC particle electrodes at pH=7, 30V applied voltage, 10g of particle electrodes, 175mL/min flow rate, and a supporting electrolyte (0.063M NaCl + 0.025M Na2SO4). The findings indicate that the effectiveness of Chemical Oxygen Demand (COD) elimination increased quickly after 20min to 66.93, 69.88, 77.59, 74.14, 81.26, 79.87, and 87.14% for Conventional Electrocoagulation (CEC). Three-dimensional electrocoagulation with granular activated carbon (TEC-RGAC), TEC-MIGAC (Al), TEC-MIGAC (Fe), and TEC-MIGAC (Al:Fe) with molar ratios of (1:1), (1:2), and (2:1) respectively were utilized. While turbidity removals were 99.04, 98.87, 99.23, 94.89, 92.42, 98.85, and 99.21% for CEC ,TEC-RGAC, TEC-MIGAC(Al), TEC-MIGAC(Fe), TEC-MIGAC(1:1), TEC-MIGAC(1:2), and TEC-MIGAC(2:1) respectively. The results demonstrated that the metal impregnation of GAC is an interesting method for achieving effective turbidity and COD removal from refinery wastewater. In both batch and repeat recycling tests, MIGAC with a mixture of aluminum and iron oxides removed turbidity and COD more effectively and efficiently than RGAC.

Process modelling and techno economic analysis for optimal design of integrated electrocoagulation-membrane system for dye removal in wastewater

Textile industry, one of the largest exporting industries in Malaysia, generates azo dyes wastewater which cannot be easily decomposed biologically due to its high stability and xenobiotic nature. Conventional electrocoagulation (EC) system requires high energy consumption, resulting in higher operating cost while membrane system suffers from fouling. To eliminate these drawbacks, an integrated electrocoagulation – membrane (ECM) system has been proposed as one of the emerging methods for treating dye wastewater. However, feasibility analysis of the proposed system is yet to be conducted. This study proposes a statistical technique to evaluate the techno-economic feasibility of the system via John's Macintosh Project (JMP) software. From JMP, an equation represents the whole model had been obtained for each of the system, EC standalone and ECM system. The models have been validated experimentally it is proven all the models can reach dye removal efficiency of 96%. Overall, the total cost for ECM system (1 V and 1.0 g of NaCl) was 40.44% cheaper than the conventional dye treatment method with total cost of 1.079 million MYR. EC standalone system at 1 V and 1.0 g however were found to be more economically feasible with 0.325 million MYR or 82.07% cheaper compared to conventional photocatalytic method. EC standalone system was also more economical than ECM system due to lower capital cost expended for installation of membrane tank and additional membrane purchase.

Moringa oleifera seed extract assisted electrocoagulation process for efficient direct dye removal from textile wastewater: Modelling, optimisation and techno-economic study

ABSTRACT This work reports the results of coupling Moringa oleifera seed extract (MOSE) with electrocoagulation (EC) for the remediation of Direct Red 80 azo dye (DR80) from contaminated synthetic aqueous solution and real textile wastewater. The electrochemical treatment was carried out using a pair of aluminium electrodes in monopolar-parallel mode. EC runs determined using Box-Behnken design under the response surface methodology (RSM) for three parameters including current density, pH, and operation time. The EC optimal conditions were current density 0.9 mA/cm2, pH 3, and time 10 min. The maximum experimental DR80 dye removal of 89.37% was close to the model prediction (76.4%). The kinetic study of the EC system represented that the removal of dye obeyed the first-order kinetic model. To improve dye removal efficiency from treated wastewater under optimal conditions, 2.5 mL/L of MOSE was added and the efficiency enhanced to above 98%. SEM and microscopic images of the sludge produced showed that the flocs formed in the hybrid system were denser and thicker than the conventional EC. The economic study revealed that switching from the EC to hybrid process reduced energy and electrode consumption from 0.015 to 0.008 kWh/m3 and 0.016 to 0.014 kg/m3, respectively, for 98% DR80 dye removal. MOSE has a substantial effect on the EC performance. Therefore, the EC/MOSE coupling process is recommended for the treatment of coloured wastewater due to its high efficiency, short operation time, and electrode and energy consumption costs.

How does arsenic speciation (arsenite and arsenate) in groundwater affect the performance of an aerated electrocoagulation reactor and human health risk?

Arsenic (As) occurrence in water resources has become one of the most critical environmental problems worldwide. The detrimental health impacts on humans have been reported due to the consumption of As-contaminated groundwater resources. Consumption of As-containing water over the long term can cause arsenicosis and chronic effects on human health due to its toxicity. Several treatment processes are available for As removals such as coagulation, ion exchange, adsorption, and membrane technologies but they have various major drawbacks. In the present work, therefore, an aerated electrocoagulation (EC) system with aluminum anodes was operated for simultaneous arsenate (As(V)) and arsenite (As(III)) removal to overcome the disadvantages of other processes such as, sludge formation, difficulties in operation, high operating costs, high energy consumption, and the requirement of pre-treatment process and to enhance the conventional EC process. The combined effects of the applied current (0.075–0.3 A), aeration rate (0–6 L/min), pH (6.5–8.5), and As speciation (As(V)-As(III)) were studied on As removal efficiency. The findings revealed that As removal mostly depended on the airflow rate and the applied current in the EC system. The highest As removal efficiency (99.1%) was obtained at an airflow rate of 6 L/min, a pH of 6.5, an initial As (V) concentration of 200 μg/L, and a current of 0.3 A, with an energy consumption of 2.85 kWh/m3 and an operating cost of 0.66 $/m3. The human health risk assessment of treated water was also examined to understand the performance of the EC system. At most of the experimental runs, the chronic toxic risk (CTR) and carcinogenic risk (CR) of As were within the permissible limits except for an airflow rate of 0–2 L/min, an initial pH of 8.5, and a current of 0.075–0.15 A for high initial As (III) concentrations. Overall, the As removal performance and groundwater risk assessment show that the EC process is a promising option for industrial applications.

Removal of tetracycline from livestock wastewater by positive single pulse current electrocoagulation: Mechanism, toxicity assessment and cost evaluation

The widespread use of veterinary antibiotics has led to the significant problem of contamination of livestock wastewater with significant amount of antibiotics. Electrocoagulation (EC) has become a prominent research topic because of the technique's ability to remove antibiotics from livestock wastewater. However, an urgent solution is needed to reduce the high operating costs associated with the process. Therefore, in this study, we developed a positive single pulse current (PSPC)-EC system to remove tetracycline (TC) from synthetic and actual livestock wastewater. Influential factors were investigated, and the optimal PSPC-EC operating parameters were identified as follows: duty ratio = 60%, pH = 4, electrode spacing = 1 cm, current intensity = 0.2 A, and conductivity = 2 mS cm−1. The mechanism of PSPC-EC was characterised using techniques including scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The TC decomposition pathway was proposed based on the generation of its intermediate products. A toxicity estimation software tool (TEST) model was used to evaluate the toxicity of TC and its main degradation products, and most of its intermediates were found to be less toxic than TC. The contribution ratios of floc adsorption and electrochemical oxidation for removing TC were 74.17% and 21.48%, respectively. The highest TC removal rate reached 95% with an operating cost of 0.011 USD/m3. Finally, under the optimum conditions identified, actual livestock wastewater was treated by PSPC-EC. Compared with conventional EC and coagulation treatment techniques that consume electricity and produce pollution, the results indicate that the PSPC-EC technique with changing current operation mode is a more cost-effective and attractive option for removing TC from livestock wastewater.

Enhancing oil removal from wastewater by combining inclined plate settler and electrocoagulation

ABSTRACT This work is aimed at developing a novel apparatus that combines inclined plate settler (IPS) and electrocoagulation (EC) to improve the emulsified oil removal efficiency with lower energy consumption. The combined process (IPS-EC) was optimized at various reactor configurations and electric field parameters of the EC process in dynamic oily wastewater treatment experiments. The results indicated that the effective removal of oil from wastewater was achieved due to the synergistic effect of EC and IPS at very low energy consumptions. The IPS could remove 74.1%±1.1% of the oil droplets from the oily wastewater. When an external pulsed direct current was applied to the metallic plates of IPS, the oil removal efficiency of IPS-EC increased to 97.0%±0.9% at a current density of 1 mA/cm2, pulsed frequency of 2000 Hz, and duty ratio of 0.9. Uniform pitting corrosion occurred on the aluminum electrode surface in a pulsed direct current waveform, which favors mitigation of electrode passivation. The energy consumption of IPS-EC was recorded as 0.66 kW.h per kilogram of oil, which is much lower than the conventional EC. The results provide a basis for the treatment of highly emulsified oily wastewater using the IPS-EC method.

Solar-Powered Electrocoagulation System for Tofu Wastewater Treatment and its Characteristic

This study aims to investigate the ability of solar-powered electrocoagulation for tofu wastewater, especially for reducing COD and TSS. This feasibility was compared with conventional electrocoagulation using electricity from the state electricity company. The study was conducted on a laboratory scale using a batch reactor electrocoagulation and aluminium electrode. The types of electrolytes used are sodium chloride and potassium chloride. The contact time is 0, 2, 4, 6, and 8 hours. The results showed that removal of COD and TSS in tofu wastewater increases with a longer electrolysis time. During two hours of electrolysis time, the removal of COD and TSS were 25 and 53.85%, respectively. This process yielded the highest COD and TSS removal of 75 and 76.9%, respectively, at 6 hours. Pseudo-second order kinetics about COD removal, both in conventional and solar panel systems, is concluded. By adding NaCl electrolytes, the conductivity of wastewater was increased, and then the removal of COD and TSS was also increased. At the end of the electrolysis time (5 hours), the pH of wastewater was neutral. The results of sludge characterization using FTIR showed the presence of hydroxyl groups, amide compound, and aromatic compound. The process of using solar panels gives results slightly different from conventional electricity, but has advantages in terms of lower operating costs and environmental friendly.

Electrochemical process for simultaneous removal of chemical and biological contaminants from drinking water.

Simultaneous management of chemical and biological contaminants in drinking water has been presented through modification in conventional electrocoagulation (EC) process. Traditional EC process using iron and aluminum electrodes removed metals but did not affect microbiological contaminants to a greater extent. Iron anode composition was amended by addition of zinc for desired antimicrobial output. To evaluate the efficiency of this system, samples were spiked with multiple element standard and microbial cultures to human unsafe contamination level. Modified EC process removed both types of contaminants making water safe for human consumption within the prescribed regulatory guidelines set by WHO/NSDWQ within 4 min. This setup removed chemical contaminants up to 100% including nitrates, fluoride, arsenic, beryllium, chromium, copper, mercury, vanadium, zinc, nickel, phosphorus, and lead. A substantial removal in cadmium (89.8%), cobalt (75.7%), and selenium (46.7%) was computed. The treatment could not prove good results for removal of boron, barium, lithium, and strontium from the spiked sample. The compositional analysis of flocs screened after spiked sample treatment confirmed the physical adsorption of metals at floc surface. Treatment technique comprehensively proved equally efficient for disinfection of most common microbiological contaminations including E. Coli, fecal coliforms, total coliforms, total plate count, Staphylococcus auseous, and Pseudomonas aeruginosa within 5 min. In EC process 220V voltage was applied through rectifier at electrodes having 15.6 cm2 surface area and 15 mm apart in 1-L water sample batches, where current varied from 0.8 to 1.6 ampere. The outcomes of the current experiment are of novel significance regarding simultaneous removal of metals and microbiological contaminants from drinking water which is not reported in previous treatment studies.

Performance of a new electrochemical process using a three-dimensional microelectrode reactor

The purpose of this paper is to design an efficient and low cost electrocoagulation reactor in which aluminum microbipolar electrodes are used and kept in suspension by an axial helical agitator. When compared to a conventional electrocoagulation reactor operated in the same conditions, the new electrocoagulation reactor shows significantly improved performance in batch mode. The use of this new electrocoagulation reactor in continuous mode and at the optimum operating conditions, Viz. Rotation speed = 300 rpm, CNaCl = 1 g/L, i = 180 A/m2, R = 10 mg dye/g of aluminum particles, allowed the dye concentration to reach a plateau with an abatement percentage of approximately 96%. The flocs that were formed appeared to be stable after 1 h.

Coupling of electrocoagulation and microflotation for the removal of textile dyes from aqueous solutions

The aim of the present research was to examine the effect of applying air microbubbles in the conventional electrocoagulation cell. Iron electrodes were used for the electrocoagulation process and a microbubble diffuser was used to generate microbubbles for the integrated flotation process. The optimum value of each operating variable (i.e pH, current density, air microbubbles flow rate, and electrolysis/flotation time) was determined experimentally in order to provide the maximum removal efficiency by this system. It was demonstrated that the introduction of microbubbles into the electrocoagulation unit significantly enhanced the dye degradation efficiency due to their buoyancy and high surface area to volume ratio which help to quickly remove pollutants. Removal efficiency of 96 % was achieved with microbubbles compared to only 70.75 % by a no-bubbles based system under the same operating conditions of 6 min electrolysis/flotation time, pH 7, 2.5 ml/min air flow rate and 10 mA/cm2 current density. Results from the present work indicate that the combination of electrocoagulation with microflotation could be an effective and economic method for reducing the concentration of dissolved pollutants in water like dyes.

Phosphorus Removal from Wastewater by Electrocoagulation with Magnetized Iron Particle Anode

Phosphorus removal from wastewater is very important in order to prevent water eutrophication. Although there are many ways to remove phosphorus, electrocoagulation (EC) is a promising method. However, the efficiency of conventional EC processes needs to be further improved. In this study, magnetized iron particle anodes used for EC were fabricated and batch experiments were conducted. The results showed that magnetized anode configuration (iron powder, iron filings, iron sheet), current density (i), as well as electrolysis time had significant effects on phosphorus removal. Particle electrodes (e.g., iron powder) with both large specific surface area and high current density were beneficial for phosphorus removal. Simultaneously, anode magnetization could also enhance the phosphorus removal to some extent based on the effect of magnetic field (MF) on water characteristics (e.g., conductivity). Combining the advantages of particle electrode and MF, magnetized particle anode was superior to other electrodes in phosphorus removal and cell voltage maintenance. Compared with the conventional plate anode, the magnetized iron particle anode was more economical and could reduce operating cost by more than 50%. The results are useful for the practical application of phosphorus removal by EC.

Arsenic Removal by Advanced Electrocoagulation Processes: The Role of Oxidants Generated and Kinetic Modeling

Arsenic (As) is a naturally occurring element in the environment that poses significant risks to human health. Several treatment technologies have been successfully used in the treatment of As-contaminated waters. However, limited literature has explored advanced electrocoagulation (EC) processes for As removal. The present study evaluates the As removal performance of electrocoagulation, electrochemical peroxidation (ECP), and photo-assisted electrochemical peroxidation (PECP) technologies at circumneutral pH using electroactive iron electrodes. The influence of As speciation and the role of oxidants in As removal were investigated. We have identified the ECP process to be a promising alternative for the conventional EC with around 4-fold increase in arsenic removal capacity at a competitive cost of 0.0060 $/m3. Results also indicated that the rate of As(III) oxidation at the outset of electrochemical treatment dictates the extent of As removal. Both ECP and PECP processes reached greater than 96% As(III) conversion at 1 C/L and achieved 86% and 96% As removal at 5 C/L, respectively. Finally, the mechanism of As(III) oxidation was evaluated, and results showed that Fe(IV) is the intermediate oxidant generated in advanced EC processes, and the contribution of •OH brought by UV irradiation is insignificant.