Electrocoagulation Reactor Research Articles

Removal of COD from petroleum refinery wastewater using electrocoagulation method

This research assessed the removability of chemical oxygen demand (COD) from petroleum effluent using aluminum-based electrocoagulation reactor. A series of batch flow studies have been conducted to evaluate the impact of current density, electrodes separation, and duration of treatment on the removal of COD from the refinery effluent. The COD levels were determined employing the remaining concentrations using spectrophotometer namely Hach-Lang and standard cuvette test (LCC 514, LCK 314, or APC 400). The findings of the current investigation indicate the capacity of the electrocoagulation technique in a relatively short processing time to reduce the COD levels. The greatest efficiency in removing COD has been determined to be 80.0%. After 100 minutes of electrolysis, a current density of 8 mA/cm2 and electrodes separation of 20 mm achieved the highest percentage removal.

Electrocoagulation As an Alternative Drinking Water Treatment to Decrease Calcium and Manganese from Groundwater: Ecuadorian Case Study

Only 37.2% of the rural population of the municipality of San Cristobal in the canton of Paute-Azuay received drinking water according to the population census carried out in 2010. Paute has 2794 inhabitants and this number is expected to grow to 3406 by 2041. Water analysis results published by the local authorities of Paute reported a high concentration of Ca2+ hardness, e.g. 442±32 mg/L of CaCO3 and a concentration of manganese of 0.97 mg/L in the groundwater catchment source. These results far exceed the concentrations suggested by the World Health Organization (WHO) for drinking water as hardness and Mn can affect the water distribution systems and the people health. Since levels under 100 mg/L of calcium hardness induce corrosion of the steel pipes of the plumbing systems, a concentration of Ca2+ ranging from 100 to 200 mg/L is recommended. On the other hand, levels of Ca2+ higher than 200 mg/L may cause scaling in the drinking water distribution systems. It is regulated that the level of Mn must be <0.4 mg/L due to the fact that this element can affect the nervous system.The aim of this work is to test the electrocoagulation process as an alternative water treatment to evaluate the removal of Ca2+ and Mn in water to design the reactor, considering technical, environmental, and socioeconomic criteria. The electrocoagulation process was performed under galvanostatic conditions in a single compartment electrochemical cell using a two-electrode setting (carbon steel) and filled with 150 mL of water coming from the sedimentation stage of the treatment plant. The experiments were performed under different current densities, pH, operating and sedimentation times using a batch process. The concentration of Ca2+ was measured by EDTA titrimetric method before and after the electrocoagulation process. In order to enhance the removal of Ca2+,Ca(OH)2 was added. Similarly, unstable parameters such as total dissolved solids, electrical conductivity, and pH were measured to assess their influence before and after the electrocoagulation process. In addition, chemical oxygen demand (COD) was measured to evaluate if additional chemicals are generated during the process. To estimate the amount of sludge generated, sedimentable solids were measured using the Imhoff cone. These results were used to design the electrocoagulation reactor. The experimental results showed that higher efficiencies are achieved in basic water (pH~8), using an applied current density of 9.56 mA/cm2 and operating and sedimentation time of 60 and 20 min respectively. Under these conditions, the efficiency of Ca2+ removal was 59.3%. It was observed that the sedimentation process did not strongly influence the efficiency of the process. The addition of 100 μL of Ca(OH)2 at 20% increases the Ca2 removal efficiency to 85% and the Mn removal efficiency was 97% under the same conditions.The electrical energy demand was calculated to be 1.13 kWh/m3, this energy consumption is associated with the dimensions for a tank with a flow rate of 11 m3/h. The dosage of Ca(OH)2 was calculated to ebe 0.13 Kg/m3 which is not linked to the reactor dimensions. No alteration in the COD concentration was registered and the generation of sludge was 2.2 times lower than the amount generated using a conventional flocculation process. Once the optimum conditions were obtained, the dimensions of the reactor were established, the diameter of the electrocoagulation reactor is 3.36 m which is 9 times of the electrode diameter, while the height of the reactor is 2 times the height of the electrode, e.g. 1.25 m. The electrode separation distance must not be longer than 0.35 times the diameter of the reactor. Electrocoagulation is a more sustainable process since it produces the coagulant in-situ with low production of sludge mostly biodegradable. In this study the removal of Ca2+ and Mn was optimized obtaining efficiencies >85% where the addition of Ca(OH)2 enhances the electrocoagulation process. The low energy consumption in the electrocoagulation reduces the operational costs of this treatment alternative.

Residence Time Distribution as a Tool for Hydrodynamic Study of Electrocoagulation Reactors Design and Scaling up

An electrocoagulation reactor operating continuously is designed for the treatment of industrial effluents in Senegal. One of the main challenges for electrocoagulation reactors design is each reactor is specific for its domain. In this paper, a methodology using residence time distribution curve (RTD) is presented and can be used for any other examples. The optimization of the operating parameters such as the flow rate, the residence time, the conductivity and so on for the treatment of these effluents requires an understanding of the reactor hydrodynamics. Thus, this hydrodynamic study based on the residence time distribution curve (RTD) showed the presence of dead zone in the reactor with a theoretical residence time of 607.76 s for an average residence time obtained from the residence time distribution curve of 554.85 s. A comparison of the curve obtained experimentally with the curves for an ideal reactor of the piston type or of a perfectly stirred type, has shown that the electrocoagulation reactor behavior is like a cascade of two perfectly stirred reactors with a difference between them of 0.15%. The numerical simulation with COMSOL allowed to illustrate the velocity fields and to highlight the preferential zones during the flow in the reactor and thus to confirm the results obtained with the hydrodynamics with a relatively low absolute error of 4.6% obtained with the least squares method.

Numerical Investigation of Degasification in an Electrocoagulation Reactor

In order to enhance retention of particulate and colloidal (organic) matter, chemical coagulation (CC) is often used prior to pressure-driven membrane filtration. This combined hybrid membrane system may be a potential solution for environmental problems dealing with drinking water treatment, water reuse, and rational waste management. In this study, an EC reactor with spiral electrodes was investigated numerically, focusing on modeling with a given design/geometry configuration and boundary conditions. Two-phase flow interactions between water and hydrogen were modeled via computational fluid dynamics (CFD). Different flow rates (Q=1−1000 L/h) through two batches of the watering stage (Case 1–3) and the degassing stage (Case 4–6) were simulated. The results provided information about flow characteristics such as sufficient retention time, water circulation, undesirable gas penetration into the water inlet channel, gas holdup during watering and degassing, and finally the optimal period for the degasification. Retention time decreases with increasing water velocity and thirty seconds seemed to be the optimal time with gas holdup of 0.020%, 0.028%, and 0.027%, respectively, for Case 4, Case 5, and Case 6. Another finding is that the consideration for the most abundant gas holdup for the typical BC was the smallest ratio of water to gas flow.

Removal of reactive blue dye from simulated wastewater by electrocoagulation using bipolar connection mode

The present study aims to remove reactive blue dye (RBD) from simulated wastewater using a batch electrocoagulation reactor connected to a power source in a bipolar-parallel mode. The aluminum electrodes used in this work have been configured to be the interior two as perforated-plates while the outer two plates as not perforated. This investigation have conducted under the effect of the reaction time, voltage applied, and pH according to the ranges (2-80 min), (15-25 volt), and (4-12), respectively. The experimental design and the analysis of results obtained have done using response surface methodology (RSM) type central composite design (CCD) and Minitab-statistical program. The core findings revealed the treatability of the present configuration of electrodes to achieve higher removal efficiency of RBD. The complete RBD-removal was attained at the optimum values of the operating variables which were 43.75 min, 17.62 volt, and 4 of the reaction time, voltage applied, and pH, respectively. The mathematical models were significant according to the ANOVA test (p<0.001). This study proved the ability of the electrocoagulation technology to remove RBD from wastewater using the present configuration of electrodes.

TREATMENT OF A TEXTILE WASTEWATER USING AN ELECTROCOAGULATION REACTOR POWERED BY PHOTOVOLTAIC SOLAR ENERGY

The textil industry uses a variety of dyes in the stage of coloring. The liquid effluent resulting at the end of the process has high turbidity and a large chemical oxygen demand. If these byproducts are dumped into natural water bodies, even in small quantities, they may produce damage to the aquatic environment and to human health. Electrocoagulation is becoming an efficient technique for the removal of pollutants from industrial effluents, it is easy to operate, and produces little sludge at the end of the treatment. In the present study, the use of an electrocoagulation reactor with aluminum electrodes proved efficient for turbidity removal from synthetic industrial effluents. The use of a solar plate of photovoltaic electricity for the functioning of the reactor was evaluated. Ideal time of treatment was 20 minutes. The use of a conventional energy source removed 63% of the turbidity. Using the voltaic solar energy source, a removal of 72% of turbidity was attained. We conclude that it is possible to use the alternative solar energy source in order to minimize costs resulting from electrical energy consumption, and, at the same time, to obtain the best results in the removal of pollutants.

Efficient removal of Cu-EDTA complexes from wastewater by combined electrooxidation and electrocoagulation process: Performance and mechanism study

In this study, combined electrooxidation and electrocoagulation (EO-EC) reactor using RuO2–IrO2/Ti and Al electrodes has been built for treatment of Cu-EDTA wastewater. Effects of current density, electrolyte, NaCl concentration, pH and initial concentration on EO-EC performance were investigated. In this study, Cu-EDTA removal efficiency increased with a higher current density. The electrolyte type exerted a significant role in EO-EC process, compared with Na2SO4 and NaNO3, NaCl was a superior supporting electrolyte because the oxidation of Cl− into Cl2 provided additional highly reactive oxidant ClO− for Cu-EDTA oxidation or mineralization. In neutral or alkaline solution, EO-EC reactor performed better than when it was acid. At the condition of current density 10.29 mA cm−2, C0(NaCl) 1 g L−1, C0(Cu) 50 mg L−1 and pH 7, the Cu and COD removal efficiency reached 99.85% and 85.01%, respectively within 60 min. The possible mechanism of Cu-EDTA removal was proposed based on SEM, EDS, XRD, FTIR and XPS analysis of the products. Cu-EDTA chelates were degraded or mineralized by direct charge transfer, chemisorbed M(·OH) and active chorine species produced on anode surface, in which degradation intermediates and mineralization products of Cu-EDTA were generated. Meanwhile, residual degradation intermediates and mineralization products were removed by electrocoagulation. In this study, EO-EC process has been proved to be an effective way for the treatment of Cu-EDTA contaminated wastewater.

Nitrate removal from groundwater using a batch and continuous flow hybrid Fe-electrocoagulation and electrooxidation system

During the last two decades nitrate contaminated groundwater has become an extensive worldwide problem with wide-reaching negative effects on human health and the environment. In this study, a combination of electrocoagulation (EC) and electrooxidation (EO) was studied as a denitrification process to efficiently remove nitrates and ammonium (a by-product produced during EC) from real polluted groundwater. Initially, EC experiments under batch operating mode were performed using iron electrodes at different applied current density values (20–40 mA cm−2). Nitrate percentage removal of 100 % was recorded, however high ammonium concentrations were performed (4.5–6.5 mg NH4+-Ν L−1). Therefore, a continuous flow system was examined for the complete removal of both nitrates and EC-generated ammonium cations. The system comprised an EC reactor, a settling tank and an EO reactor. The applied current densities to the EC process were the same as those in the batch experiments, while the volumetric flow rates were 4, 6 and 8 mL min−1. Regarding the current density of the EO process was kept constant at the value of 75 mA cm−2. The percentage nitrate removal recorded during the EC process ranged between 52.0 and 100 %, while the NH4+-N concentration at the outlet of the EO reduced significantly (53–100 %) depending on the applied current density and the volumetric flow rate. Also, the dissolved iron concentration in the treated water was always below the legislated limit of 0.2 mg L−1 (up to 0.027 mg L−1). These results indicate that the proposed hybrid system is capable of denitrifying real nitrate contaminated groundwater without generating toxic by-products, therefore making the water suitable for human consumption.

A prediction method of electrocoagulation reactor removal rate based on Long Term and Short Term Memory–Autoregressive Integrated Moving Average Model

In the process of electrochemical wastewater treatment, the removal rate of electrocoagulation reactor will be affected by various factors such as the pH value of wastewater solution, the current density, the wastewater flow rate and the initial concentration of heavy metal ions. Therefore, this study proposes a prediction method of the removal rate of the electrocoagulation reactor based on deep learning Long and Short-Term Memory (LSTM) network combined with the Autoregressive Integrated Moving Average Model (ARIMA) commonly used in engineering. Firstly, according to the concentration of heavy metal ions in the outlet and inlet solution of the reactor, the calculation formula for the removal rate of the reactor is defined. Secondly, in order to deepen the LSTM network model to analyze and learn the change trend of the historical removal rate data, the gradient value of the historical removal rate of the reactor before and after the change is extracted as its change feature value, and this feature value is taken as one of the input variables of the LSTM network model. Comprehensive analysis considered important factors such as the historical removal rate value of the reactor, the initial pH value of the wastewater solution, the voltage and current value, and the wastewater flow rate as the input variables of the LSTM deep learning network. The predicted value of the removal rate of electrocoagulation reactor is concluded by testing the combination of activation function and the number of fully connected layers, and the error compensation of the predicted value is carried out by using the ARIMA model. The effectiveness of the proposed method is verified by the industrial data collected from a wastewater treatment plant.

A systematic diagnosis of state of the art in the use of electrocoagulation as a sustainable technology for pollutant treatment: An updated review

Electrocoagulation (EC) and electrocoagulation-flotation (ECF) are of widespread interest owing to their effectiveness for the simultaneous abatement of a broad range of pollutants in drinking and waste waters, but their capability can vary significantly depending on the operating conditions. The effect of operating conditions on the performance of EC has been the subject of much debate over the last few decades. This review aims to focus on the application of EC/ECF processes for pollutants removal under different operating conditions, emphasizing the principal issues that compose the foundation of EC/ECF. It has been found that the current density (typically 1–20 mA/cm2), type of electrode (Al or Fe), and electrolysis time are the key process parameters that influence performance. Although some key mechanisms of pollutant abatement in EC/ECF processes have been identified, recent studies have begun to reveal how the underlying removal mechanisms using the EC/ECF processes depend on the nature of pollutant. Key mechanisms of pollutant abatement include charge neutralization, reduction–oxidation, and precipitation/co-precipitation. The development of improved or innovative cell designs, as well as systematic modeling of EC reactors, are needed. Future research focused on hybrid technologies with cost-effective energy supply may lead to innovative treatment options for wastewater treatment.

Phosphorous removal from anaerobically digested municipal sludge centrate by an electrocoagulation reactor using metal (Al, Fe and Al-Fe) scrap anodes

Phosphates are a major cause of eutrophication and growth of algal blooms in surface waters. The current study investigated phosphorus removal from sludge centrate effluent (SCE) of a municipal wastewater plant by packed-bed electrocoagulation (EC) reactor. Distinctively, iron (Fe), aluminum (Al) and Al-Fe hybrid scrap anodes were used. The influence of initial pHi, applied current and packed anode bed density were evaluated. Phosphorous removal efficiency of 99.99 % was obtained at applied current of 0.20A with anode bed densities of 0.18 kg Al/m3 (pHi 5.0) and 0.48 kg Fe/m3(pHi 7.0). Optimum operating costs entailing sludge disposal, chemical, energy and electrode consumption were calculated as 0.379 US $/m3 (6.04 $/kg PO4-P) for Fe scrap, 0.494 US $/m3 (9.46 $/kg PO4-P) for Al scrap and 0.501 US $/m3 (9.59 $/kg PO4-P) for Al-Fe hybrid scraps. Phosphorus removal per electrochemically generated metal was 191.22 mg P/g Al, 104.88 mg P/g Fe, and 61.08 mg P/g (Al + Fe). The molar metal to phosphorus ratio at optimum conditions were calculated as 5.41, 3.97 and 7.65 mol/mole for Al, Fe and Al-Fe, respectively. The key mechanisms for phosphorus removal were metal-phosphorus precipitation and adsorption. Herein, metal scrap anodes have been proved effective for phosphorous removal from SCE.

Tangential effluent inlet in a cylindrical electrocoagulation reactor containing curved electrodes, and its use in crude oil in water treatment

ABSTRACT A continuous electrocoagulation reactor, with curved electrodes, polarity switch, and cylindrical geometry, was used for emulsified crude oil in water separation. Apparatus novelty consists of an inlet arranged to promote a circular flow regime. The effects of flow rate (2 and 6 mL.s-1), electrical current (2 and 4 A), and distance between electrodes (1.5 and 2.5 cm) were investigated using a full factorial design and statistical analysis. Using 6 mL.s−1 flow rate, 2 A electric current and 2.5 cm electrode distance; 86% oil removal was obtained at a pH < 9.0. For this configuration, the system will process 21.6 L of oily emulsion while consuming 6.92 Wh. Oil removal increased with flow rate, a novel characteristic created by the unusual geometry of the system.

Coupling of electrocoagulation and powder activated carbon for the treatment of sustainable wastewater.

The present research work is based on an electrochemical technique in combination with powdered activated carbon (PAC) for the removal of micropollutants by adsorption as an advanced stage purification step from effluents of pilot plant wastewater treatment plants (WWTP). The effluents of sedimentation tank comprised of wastewater plus PAC (WWPAC). The pilot plant mainly consists of two parts: the first one consists of electrocoagulation (EC) reactor, and the second consists of electrophoretic deposition (EPD) discs and electroflotation (EF) setup. The electrocoagulation (EC) reactor consisted of the electrode material (Al and Fe). Both types of electrodes have been tested with the outflow of sedimentation tank. The outflow from the sedimentation tank has been entered into the EC reactor for the determination of EC reactor efficacy for the successful accomplishment of EC process at the designed pilot plant for WW treatment. The effect of different operational parameters, PAC dosage (20 mg), electrode nature (Fe and Al) and current density (0.34-2.02 A/m2), has been studied to find out the optimum conditions. Sludge volume index (SVI) of the sludge, thermogravimetric (TG), differential thermal analyses (DTA) and particle size distribution (PSD) of the flocs generated after the EC process has also been studied. The turbidity, pH and conductivity of effluents before and after EC treatment have also been carried out. The research work performed detailed analysis of the wastewater effluents at pilot plant scale and gave promising results for future work in advance wastewater treatment direction.

Optimization of continuous electrocoagulation-adsorption combined process for the treatment of a textile effluent

Experimental setup: (a): Real schematic of pilot, (b): 3D scheme of pilot/ 1: tank with untreated effluent, 2: variable frequency pump, 3: Electrocoagulation reactor, 4: adsorption reactor, 5: mechanical stirrer, 6: tank for sedimentation, 7: acrylic container of the suspension of clay, 8: mechanical mixer of the suspension of clay, 9: 12 Volt peristaltic pump, 10: control panel of current supplier, 11: 10 parallel iron electrodes. • The full continuous combined process based on electrocoagulaion-adsorption on crude clay is a very efficient process for textile effluent decontamination. • The achieved removal efficiencies of color, COD and TSS were respectively 96.87%, 89.77% and 84.46%. • The achieved treated effluent fulfill the Tunisian standards of rejected wastewater and could be used in preparation process or in irrigation. • Treatment efficiencies were enhanced at neutral pH range, slow effluent flow rate, high voltage and high adsorbent suspension flow rate. The aims of this study is to design and optimize the functioning of a full continuous combined process based on electrocoagulaion-adsorption on crude Tunisian clay to treat a real textile effluent. The clay characterization shows that the used clay is a rich-smectite clay. The response surface methodology (RSM) technique based on Box-Behnken design (BBD) was used to optimize the process. At optimum conditions which are initial pH solution of 8.24, effluent flow rate of 0.5 L·min −1 , voltage of 70 V, and added suspension of clay flow rate of 100 ml·min −1 the achieved color, chemical oxygen demand (COD) and total suspended solid (TSS) removal efficiencies were respectively 96.87%, 89.77% and 84.46% with 0.75USD·m −3 as total cost. The additional laboratory experiments at optimum conditions agree with the predicted results, which confirm the accuracy and the capability of RSM to predict results in the defined space. Finally the designed process could be a good eco-friendly alternative to treat and reuse wastewater in industrial process with reasonable cost.

Pengaruh Jarak Elektroda Dan Kuat Arus Pada Pengolahan Air Gambut Dengan Proses Elektrokoagulasi Secara Kontinu

Peat water is surface water that inundates an area, formed from a pile of organic material for a long time. Peat water can cause skin irritation and metabolic disorders. The purpose of this study was to determine the application of the electrocoagulation method can be used to neutralize pH, and reduce levels of TSS and Fe in peat water treatment and also to determine the effect of changes in electrode spacing and current strength on decreasing TSS and Fe levels and neutralizing the pH of peat water. The parameters tested include pH, TSS (Total Suspended Solid), and Fe. The electrocoagulation process uses electric power which flows in the direction through the electrodes. Electrocoagulation reactor paired with a cable connected to the power supply and then connected to an electric current with a variation of current strength (1.0; 1.4; and 1.8 A) and electrode distance variations (0.5; 0.75; 1 inch). The results of this study giving the optimum conditions obtained at a strong current of 1.8 A and 0,75 inch electrode distance with an increase in pH from 3.5 to 6.8, a decrease in TSS from 128 to 36 mg / L, a decrease in Fe of 78.9% from 2.405 mg / L to 0.506 mg / L.

Removing arsenate from water using batch and continuous-flow electrocoagulation with diverse power sources

Recently, electrocoagulation (EC) has emerged as a promising method to treat contaminated water. In this study, a novel EC system using stainless steel electrodes was applied to remove arsenate (As(V)) in water. An operation time of 5 min, electrical potential difference of 7.5 V, and inter electrode distance of 1 cm were identified as optimal condition for removing As(V) (eliminated 92 % of As(V) from 0.1 mg As(V)/L solution). In the batch study using a 9 V rechargeable battery and a small 12 V solar panel, the EC reactor removed 93 % and 98 % of As(V) from 0.1 mg As(V)/L solution, respectively, and As(V) concentration in treated water was lower than that of the drinking water guideline of World Health Organisation (WHO) (0.01 mg/L). In the continuous water flow study, a small cost-effective system (reactor volume of 1 L, cost $15 AUD) using a small 12 V solar panel could successfully treat 12 L contaminated water per hour. During 4 h of continuous testing, the system’s efficiency in removing As(V) remained constant at >91 %. The operation cost for the treatment of As(V) – contaminated water in continuous operation mode is $0.240 AUD/m3 water for the direct current (DC) electrical system and $0.262 AUD/m3 for the solar system. In a pilot field study with contaminated groundwater (0.03 mg total As/L) in Hanam province, Vietnam, the EC system using solar energy (12 V) was able to reduce As concentration to below the Vietnamese and WHO permissible drinking water limit in 1 min.

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.

Arsenic Removal from Highly Contaminated Groundwater by Iron Electrocoagulation—Investigation of Process Parameters and Iron Dosage Calculation

Electrocoagulation (EC) is gaining increased attention for water treatment as it efficiently removes various water contaminants. Therefore, EC was applied to remove arsenic from groundwater of a highly contaminated site in Hamburg, Germany. Groundwater containing 3250 and 14,600 µg/L arsenic, mainly as Arsenite (As(III)), was treated in three different EC batch reactors using a monopolar parallel electrode-configuration. This study focused on iron EC with constant current densities and variable voltage, to investigate the influence of current density, surface to volume ratio, initial arsenic concentration and water volume on the removal of arsenic and the influences on the groundwater composition. Arsenic removal &gt;99.9% was achieved for configurations with high iron dosage after four hours of EC treatment. German drinking water standard for arsenic (&lt;10 µg/L) was obtained after around two hours depending on the applied current densities. Arsenic removal efficiency shows independence from current density, surface to volume ratio, initial concentration and water volume, with respect to the calculated iron dosage. Consequently, the dimensioning and regime of efficient operation of the EC reactor for arsenic removal from groundwater can be calculated solely from the iron dosage determined by the applied current.

Continuous flowing electrocoagulation reactor for efficient removal of azo dyes: Kinetic and isotherm studies of adsorption

Abstract The electrocoagulation process is an effective and economical technology for the treatment of industrial wastewater. So, it is particularly important to develop an efficient electrocoagulation reactor. To this end, a novel electrocoagulation reactor is described to effectively remove azo dyes from aqueous solutions utilizing electrocoagulation, in which the electrode plate is bent. Continuous wastewater flows in the reactor will promote faster and more stable growth of flocs This paper took methyl orange as a study object. It was concluded that methyl orange decolorization rate was 92.35% under the optimal conditions while flat electrode under the same conditions of methyl orange decolorization rate was only 58.9%. The results meant that the second-order kinetic model was most in line with the experimental results, which indicated that the chemisorption mechanism controls the adsorption of methyl orange. Furthermore, the results showed that the Langmuir isotherm model was more in line with the experimental results, and showed that the experiment was single-layer adsorption on the adsorbent surface. Under the optimal conditions of the electrocoagulation process, electrode consumption is 0.2376 g, and the electrical energy consumption is 1.5925 KWh m−3 during a single operation.

Application of hybrid electrocoagulation-filtration methods in the pretreatment of marine aquaculture wastewater.

The aim of this study was to provide technical means and data support for enhancing the filtration pretreatment capacity of a recirculating aquaculture system. A continuous flow electrocoagulation (EC)-filtration system was designed and its application in the pretreatment of marine aquaculture wastewater was studied. The influences of anode combination modes, hydraulic retention times (HRTs) of the EC reactor and filter pore sizes on the water treatment capacity were investigated. Results showed that EC could significantly enhance the treatment efficiency of the filtration equipment used in subsequent steps. Al-Fe electrodes used as anode led to better processing capacity of this system, and the optimum anode was 3Al + Fe. With the increase of HRT and decrease of filter pore size, the enhanced effect of the EC process on the filter was more obvious. When the current density was 19.22 A/m2, the anode was 3Al + Fe, the HRT was 4.5 min and the filter pore size was 45 μm, the removal efficiency of the system for Vibrio, chemical oxygen demand, total ammonia nitrogen, nitrite nitrogen (NO2--N), nitrate nitrogen (NO3--N) and total nitrogen was 69.55 ± 0.93%, 48.99 ± 1.42%, 57.06 ± 1.28%, 34.09 ± 2.27%, 18.47 ± 1.88% and 55.26 ± 1.42%, respectively, and the energy consumption was (26.25 ± 4.95) × 10-3kWh/m3.