Performance of Electrocoagulation Process with Copper Electrodes for Tannery Wastewater Treatment

Abstract

The effluents from the tanning industry pose challenges due to the complex and difficult-to-manage wastewater generation process. Usually, the main issue in tannery wastewater is the high levels of chemical oxygen demand (COD), chlorides (Cl), and chromium (Cr), which have a negative impact on human health and the environment. Since the conventional biological treatment methods are not effective for treating tannery wastewater, the main aim of this study was to assess the performance of the electrocoagulation process (EC) in treating tannery wastewater by copper electrodes. The study was conducted through an investigation of stirring speeds (low (60 rpm), medium (780 rpm), high (1500 rpm)), current densities (4, 8, 12, and 16 mA/cm²), and reactor volume capacities (0.5, 1, 1.5 L) over an examination period of 60 min. The EC process has proven its high efficiency in removing pollutants. The results showed the best removal efficiencies, where the removal rates of COD, Cl, and Cr reached 92.3%, 96.5%, and more than 99%, respectively, at the following optimum parameters: stirring speed of 60 rpm, current density of 4 mA/cm², and reactor volume of 1 L. Corrosion of the Cu electrodes was observed via scanning electron microscope (SEM) imagery, and the generated sludge was analyzed via Fourier transform infrared (FTIR) spectroscopy.

1. Introduction

The industrialization era has provided major economic benefits globally, with the tanning industry being a key contributor [1]. Tanning, a chemical process that converts animal hides into leather, involves four stages: beam house operations, tanning, re-tanning, and finishing [2,3]. These processes generate large volumes of chemically complex wastewater, containing over 175 substances such as sodium chloride, sodium hydroxide, chromium, ammonium chloride, sulfuric acid, and various organics, alongside high water consumption rates [1]. Such effluents are toxic, strongly colored, and turbid, making treatment highly challenging. Their uncontrolled discharge poses severe environmental and health risks, including kidney failure, skin diseases, and eye disorders [4], as well as eutrophication and biodiversity loss and increases in salinity, COD, and suspended solids [5,6,7].

Conventional biological and chemical treatment methods have significant drawbacks. Biological processes are inhibited by toxic compounds, produce excessive sludge, and require long treatment times [8,9], while chemical methods may cause secondary pollution. Consequently, electrochemical treatment technologies, especially electrocoagulation (EC), have gained attention for removing pollutants such as phosphates, nitrates, heavy metals, pesticides, and dyes [10]. Although first applied in England (1889) and the USA (1946) [11], EC faced early cost limitations. Recent advances, however, highlight its efficiency, environmental compatibility, and adaptability for treating complex wastewater [11,12]. EC achieves high removal efficiency in a short time, generates minimal sludge, is easy to operate, and produces high-quality effluents [13].

The main EC system generally includes an electrolytic cell containing an anode and cathode metal electrodes externally linked to a DC power source, and these electrodes are submerged in the solution undergoing treatment [12]. Iron and aluminum electrodes are commonly employed in EC cells due to their availability and established reliability. In summary, the EC process comprises three consecutive steps that involve the in situ generation of coagulated ions. These steps are [10]: (i) the electrolytic oxidation of sacrificial electrodes to release coagulants; (ii) pollutant destabilization, particle suspension, and breaking of emulsions; (iii) the accumulation of destabilized phases to form flocs.

When a potential is applied, redox reactions take place at both the anodes and cathodes. At the anode, the metal undergoes oxidation, which leads to the release of ions into the solution. These ions interact with water molecules to generate hydroxides, contributing to the coagulation process [14]. Apart from metal oxidation, water oxidation may also occur at the anode, contingent upon the anode potential. Additionally, if chloride ions are present in the electrolyte, chlorine gas evolution may occur, and the evolved chlorine gas can aid in pollutant removal and disinfection [10]. The anodic reactions can be described as follows, where M is the metal electrode and n is the number of electrons transferred [14].

M → Mⁿ⁺ + ne⁻

(1)

2H₂O → 4H⁺ + O₂ + 4e⁻

(2)

The dissociation of the anode aligns with Faraday’s law, which is represented by the following equation (Equation (3)) [12]:

$$m={\displaystyle \frac{\mathrm{M}\mathrm{w}\times \mathrm{I}\times \mathrm{t}}{ F \times Z}}$$

(3)

where m is the mass of anode dissolved (g), Mw is the molecular weight (g/mol), I is the current (A), t is the operating time (s), F is Faraday’s constant (96,485 C/mol), and Z is the number of electrons involved in the specific redox reaction occurring at the electrode.

The hydrogen gas bubbles and hydroxide ions are generated due to the reduction of water at the cathode, as in the following equation (Equation (4)) [15]:

2H₂O + 2e → H₂ + 2OH⁻

(4)

There are numerous factors affecting the efficiency of the EC process, including the current density applied, electrode material and configuration, inter-electrode spacing, solution pH, initial ion concentration, solution conductivity, temperature, reaction time, and treated water type [10].

In recent times, different researchers have used copper as electrodes for the EC process instead of iron and aluminum. This has proven effective in treating many pollutants and heavy metals from wastewater [16]. The main reactions occurring in copper electrodes can be identified as follows [17]:

At the anode:

2 Cu → 2 Cu²⁺ + 4 e⁻

(5)

At the cathode:

4 H₂O + 4 e⁻ → 2 H₂ + 4 OH⁻

(6)

A study has investigated the performance of the EC process by iron electrodes in terms of removing chromium from tannery wastewater. The chromium removal reached 100% at the optimum values of 13 mA/cm² current density and a pH of 7 [13]. Another study achieved 100%, 84%, and 85% removal efficiencies for COD, color, and turbidity, respectively, using the EC process with aluminum electrodes in tannery wastewater treatment. This involved an operating time of 21 min [18]. In a previous study, copper (Cu) electrodes were used for the removal of coliforms from slaughtering wastewater. The study showed that the EC process by copper electrodes had the ability to remove the total coliform from poultry slaughterhouse wastewater at 30 V over the reaction time of 10 min [19]. Cu electrodes are also studied in terms of nickel (Ni) and hexavalent chromium (Cr(VI)) removal from synthetic and real wastewater. The EC process achieved 99.96% and 98% removal efficiencies for Ni and Cr, respectively, with the following parameters: pH = 9.2; current density = 5–10 mA/cm²; electrode spacing of 4 cm’ electrolytes = NaCl [16].

Since the previous studies have not tested the performance of the EC method by copper electrodes on tannery wastewater treatment yet, this research aimed to investigate the performance of the EC process using copper electrodes in treating the wastewater effluents from the tanning industry. The research aimed to achieve the specific objectives as follows: (i) assess the performance of the EC system for treating tannery wastewater in the removal of COD, chlorides (Cl), and chromium (Cr); (ii) investigate the performance of the copper electrodes in the treatment process; (iii) examine various operating parameters such as the stirring speeds, current density (CD), and reactor volume capacity to enhance the performance of the EC process through identifying the optimal conditions; (iv) analyze the electrodes’ morphology.

2. Materials and Methods

2.1. Wastewater Characteristics

The wastewater used in the study was from the effluent of the tannery industry in Egypt, which contained contaminants such as organic matter, chlorides, and chromium. Sodium chloride was used in the experiment as a supporting electrolyte with a 1000 mg·L⁻¹ concentration. The characteristics of the tannery wastewater used in the experimental work are in

Table 1. Characteristics of the raw tannery wastewater.

Parameter	Value
pH	8 ± 0.5
COD (mg·L−1)	786 ± 50
Cr (mg·L−1)	51 ± 10
Cl (mg·L−1)	1099 ± 70
TDS (mg·L−1)	1801
Conductivity (μS/cm)	2686

.

2.2. Setup and Operation of Cu-EC

The EC unit is shown in Figure 1. The experiments were carried out over an experimental time of 60 min while maintaining a temperature of 20 ± 2 °C. All experiments were performed while the system operated in batch mode. The EC unit consisted of a 1 L glass beaker with magnetic stirring and two electrodes, which were connected to a DC power source. Copper electrodes were utilized as an anode and a cathode for the EC process. An area of 36 cm² of each electrode was submerged at pH 8, and the gap distance between electrodes was 3 cm. During the experiments, different current densities (4, 8, 12, and 16 mA/cm²) and stirring speeds (low (at 60 rpm), medium (at 780 rpm), and high (at 1500 rpm)) were investigated. The current intensity and voltage were measured using a multimeter during the experiments. The samples were then periodically withdrawn for an additional analysis.

COD, Cl, and Cr were measured using standard methods for the examination of water and wastewater, while the pH was measured by a pH meter (EcoSense^® pH1000A, YSI Inc., Yellow Springs, OH, USA). Additionally, the DTS and conductivity were measured by a conductivity meter (EcoSense^® EC300A Conductivity Meter, YSI Inc., Yellow Springs, OH, USA). The Cu electrodes’ morphology was investigated using scanning electron microscopy (SEM). The analysis for the generation of sludge from the EC process was investigated by a Fourier transform infrared (FTIR) spectrometer (Nicolet is10 AKX1200, Madison, WI, USA), which was used to record the bonding state. The samples were converted to thin disks after being mixed with KBr. The infrared radiation range was from 400 to 4000 cm⁻¹.

2.3. Analysis of Samples and Calculations

Influent and effluent samples were periodically collected and tested. The removal efficiency (percentage) was determined after treatment using the following formula (Equation (7)):

Removal efficiency (%) = (C_o − C_eff)/C_o × 100

(7)

where C_o and C_eff refer to the concentrations of influent and effluent pollutants, respectively.

3. Results

3.1. Effects of Stirring Speeds on EC for Treatment of Tannery Wastewater

The effects of various stirring speeds on the experiments were studied for the EC process and for their impact on the removal efficiency of the contaminant. Three levels of stirring speeds were tested to obtain the best stirring speeds and at the minimum and maximum current densities (CD = 4 mA/cm², CD = 16 mA/cm²). The experiments were carried out at different stirring speeds as follows: low (60 rpm), medium (780 rpm), high (1500 rpm). The removal efficiency rates of COD, Cl, and Cr over the 60 min examination time at the various stirring speeds for the EC process are shown in Figure 2. The results assured the EC process’s efficacy with high removal rates. In all experiments, the removal rate was at its peak level within the initial 10 min, and gradually decreased after that. The COD removal efficiency reached 88.3% after 10 min with low stirring speed, and at the end of the time, the removal efficiency reached 95.6% with medium stirring speed. The Cl removal efficiency reached 96% with medium stirring speed after 10 min, and after 60 min reached 96.9%. As for Cr, the removal efficiency reached 98.94% after 10 min with low stirring speed, and by the end of the time, the chromium was almost completely removed, with the optimum removal reaching more than 99%.

From the previous results, to determine the best stirring speed, Response Optimizer was used to identify the combination of input variable settings that optimizes a set of responses. Minitab^® determines the optimal settings for the variables by maximizing the desirability of the composite. Optimization was performed for COD, Cl, and Cr after 60 min. The composite desirability (0.9221) was close to 1, indicating that the settings seem to achieve favorable results for all responses as a whole. Therefore, the low stirring speed was determined as the best stirring speed for the EC process.

The stirring speed’s primary purpose is to transfer the generated coagulant material from the electrode solution to the reactor. In case the material of the coagulant is not dispersed very well inside the reactor, this may lead to non-homogeneity in the reactor content, which affects the efficiency of the treatment process. Additionally, the stirring speed has a great impact on the homogeneity of the system’s variables, such as the pH and temperature. However, applying high stirring speeds may damage the clumps formed in the reactor, causing the formation of small flocs that are difficult to remove from the water [20]. This explains why the removal efficiency increased when using a lower stirring speed.

3.2. Effect of CD on EC for Treatment of Tannery Wastewater

After selecting the best stirring speed, identifying the appropriate current density value has a significant impact on the treatment efficiency in the EC process. Experiments were conducted at various current density values (4.0, 8.0, 12.0, and 16.0 mA/cm²) to select the optimal CD value within this range. The removal efficiency rates of COD, Cl, and Cr over the 60 min examination time at the various current densities for the EC process are shown in Figure 3. In all experiments, the removal rate was at its peak level within the initial 10 min, and gradually decreased after that. The COD removal efficiency reached 82.7% after 10 min at CD = 16 mA/cm², and at the end of the time, the removal efficiency reached 94.5% at CD = 12 mA/cm². The Cl removal efficiency reached 54.6% after 10 min at CD = 4 mA/cm², and after 60 min reached 96.5%. As for Cr, the removal efficiency reached 94.3% after 10 min at CD = 4 mA/cm², and by the end of the time, the chromium was almost completely removed, with the optimum removal reaching more than 99%.

From these results, Minitab^® was used to determine optimal settings for the variables by maximizing the desirability of the composite. Optimization was performed for COD, Cl, and Cr after 60 min. The composite desirability was close to 1 in the case of CD = 4 mA/cm². Therefore, CD = 4 mA/cm² was chosen as the best CD for the EC process.

The current density is one of the main parameters that determines the rate of the coagulant dosage and bubble production, along with the size and growth of the flocs that impact the removal efficiency during the EC process. The anode dissolution rate increases with the increase in CD, where a higher quantity of copper hydroxide flocs is produced, which leads to an increase in removal efficiency [16]. However, increasing the CD above the optimal value causes overdose of metal ions, which can destabilize the particles, and this leads to a decrease in removal efficiency [21]. Therefore, the CD that was applied at 4 mA/cm² was the optimal CD.

3.3. Effect of Volume on EC for Treatment of Tannery Wastewater

The effect of various volume capacities on the experiments for the EC process was studied to identify the best volume capacity in the treatment process. The three volumes were tested (0.5, 1, and 1.5 liters) to obtain the optimal volume within these ranges. The performance of the EC process in removing COD, Cl, and Cr over an examination time of 60 min at various volume capacities is shown in Figure 4. In all experiments, the removal rate was at its peak level within the initial 10 min, and gradually decreased after that. After 10 min, the COD removal efficiency reached 81.13% at V = 0.5 L, and at the end of the time, the removal efficiency reached 94.23%. The Cl removal efficiency reached 95.54% after 10 min at V = 1 L and after 60 min reached 96.45%. As for Cr, 98.94% was removed after 10 min at V = 1 L, and by the end of the time, the chromium was almost completely removed, with the optimum removal reaching more than 99%.

From these results, Minitab^® 21 was used to determine optimal settings for the variables by maximizing the desirability of the composite. Optimization was performed for COD, Cl, and Cr after 60 min. The composite desirability was close to 1 in the case of V = 1 L. Therefore, V = 1 L was chosen as the best volume for the EC process.

The larger the reactor volume, the better the removal efficiency. The increase in reactor volume enhanced the electrical transport and ensured better chemical dissolution of metal, which led to high rates of removal efficiency. Nevertheless, an excessive increase in the reactor volume over the optimum limits results in reducing the current density consumption, which has a negative effect on the removal efficiency [22].

3.4. Electrode Morphology

The morphologies of copper electrodes were investigated in order to show changes after the EC process. The anode electrode was examined for the simple configuration of the EC process before and after the treatment, as illustrated in Figure 5. Corrosion was observed for the Cu anode in the EC process, which means that the treatment process had occurred. In the EC anode, as shown in Figure 5b, cracks were observed on the surface, and this was due to the consumption of copper at the active sites of the electrodes, where oxygen generation occurs on their surfaces [16].

3.5. Characterization of the Generated By-Products

The characterizations of the sludge resulting from the EC process have already been analyzed through FTIR, as shown in Figure 6. From these observations, there is a kind of convergence between the spectra obtained from the sludges generated from EC. The peaks observed between 1500 and 2000 cm⁻¹ indicate the presence of double bonds, while the absence of peaks in the range 2000 to 2500 cm⁻¹ indicates the absence of triple-bonded compounds in the sample [23]. The peaks observed between 2500 and 4000 cm⁻¹ correspond to the single bond region. The FTIR analysis of the sludge samples revealed a broad and intense peak in the 3000 to 3500 cm⁻¹ wave number range. This indicates the presence of hydroxyl ions (OH⁻). The existence of these OH groups can promote the adsorption of counterions during the sedimentation process [24].

3.6. Electrical Energy Consumption and Cost Analysis

A key consideration in selecting a treatment process for large-scale applications is its economic feasibility [25]. The costs associated with electrochemical systems can be categorized into two primary components: capital costs (CAPEX) and operating costs (OPEX). Capital costs encompass expenses related to the construction of the system and include permanent components such as piping, fittings, and pumps. Operating costs, on the other hand, are derived from four main factors: electrical energy consumption during the treatment process (EEC), electrode dissolution (ED), chemicals used (CC), and costs associated with sludge handling (Sl). Routine maintenance costs are not included in this calculation. The following equation is employed to determine the operating costs for the electrocoagulation system:

OPEX = C1 × EEC + C2 × ED + C3 × CC + C4 × SL

(8)

where C1, C2, C3, and C4 are the energy price (0.039 US$/KWh), electrode price (for copper 7 US$/kg), H₂O₂ price (0.3 US$/kg), and cost of sludge handling (0.16 US$/Kg), respectively [26]. To evaluate the economic feasibility of the EC used in this study, the OPEX for the system’s optimal conditions was calculated with treatment durations of 10 min and 60 min, as shown in

Table 2. Components related to the operating costs of EC under optimal conditions.

	Unit	EC After 10 Min	EC After 60 Min
Energy Consumption	(kWh/m3)	0.147	1.659
Electrode Consumption	(kg/m3)	0.057	0.341
Sludge Production	(kg sludge/m3)	0.371	1.045
Total Operating Cost	(US$/m3)	0.463	2.622
COD Removal	%	75.8	92.2
Cr Removal	%	98.9	>99
Cl Removal	%	95.5	96.5

. When evaluating the results, it is obvious that the removal efficiencies of the pollutants increase with increasing treatment. However, these increases were associated with increases in operational costs. Specifically, after 10 min of treatment, the removal efficiency for COD was 75.8%, and for Cr, it was 98.9%, with an operating cost of 0.46 US$/m³. In contrast, after 60 min, the removal efficiency for COD rose to 92.2%, and for Cr, it reached more than 99%, with an operating cost of 2.60 US$/m³. When increasing the duration of treatment from 10 min to 60 min, the increases in the removal efficiencies of COD and Cr reached 16.4% and 1.1%, respectively. The analysis revealed that the increase in operating cost per 1% enhancement in COD removal was 0.13 US$/m³, while for Cr removal, it was significantly higher at 2.00 US$/m³. These data suggest that while extending the treatment duration from 10 to 60 min resulted in a substantial improvement in COD removal efficiency, it did not yield further gains in Cr removal efficiency. Overall, the use of copper electrodes in the EC process is determined to be more economically feasible.

3.7. Kinetic Study

The design of reactors can be performed when the kinetics of the processes are known, which are dependent on the type and composition of the wastewater [10]. To understand the reaction rates of Cr and Cl removal using EC, a kinetic study was performed. Linear forms of pseudo-first order (PFO) and pseudo-second order (PSO) kinetics were applied, and the results showed that Cr removal obeys PSO kinetics (R² ≥ 0.989), while Cl follows PFO kinetics (R² ≥ 0.976). The removal of Cr follows PSO kinetics at every current density (as shown in

Table 3. Parameters for PSO for Cr removal.

Current Density	qe (mg L−1)	k2 (L mg−1 min−1)	R2
4 mA cm−2	50.96	0.284	0.999
8 mA cm−2	36.90	0.018	0.994
12 mA cm−2	39.53	0.015	0.992
16 mA cm−2	43.80	0.012	0.988

), implying that the rate-limiting step is a surface-mediated reaction (chemisorption or electron transfer) rather than mass transfer. The equilibrium adsorption capacity (q_e) indicates that a higher CD improves the Cr removal performance. However, the PSO rate constant (k₂) suggests that while a higher driving force achieves a higher final capacity, the initial adsorption rate is faster at the lower CD.

On the other hand, Cl obeys PFO kinetics (as shown in

Table 4. Parameters for PFO for Cl removal using ECP.

Current Density	k1 (min−1)	R2
4 mA cm−2	0.0512	0.989
8 mA cm−2	0.0184	0.976
12 mA cm−2	0.0161	0.972
16 mA cm−2	0.0095	0.965

), indicating a physical process such as sweeping by Cu hydroxide flocs or simple co-precipitation. The PFO rate constant (k₁) showed a decreasing trend with increasing CD. This inverse relationship implies that although an elevated CD level enhances the overall efficiency of coagulant generation and Cl removal, the initial removal rate per unit concentration of Cl is more rapid at a lower CD level. This behavior aligns with a diffusion-controlled process, since lower driving forces can lead to more efficient initial mass transfer.

3.8. Comparison of the Results with the Literature

Based on prior research,

Table 5. Previous studies for EC technology.

Pollutants Removed	Wastewater Type	Type of Treatment	Electrode Material (Anode/Cathode)	Operating Conditions	Removal Efficiency (%) and Power	Reference
COD	Rice grain-based distillery effluent	EC	Copper/Copper	pH = 3.5 CD = 89.3 A/m2	COD = 80% EEC = 11.42 Wh/L	[27]
COD–Color–Dye– Turbidity	Textile wastewater	EC	Stainless steel	pH = 3 CD = 10 mA/cm2 Time = 50 min	COD = 76% Color = 94% Dye = 95% Turbidity = 95%	[28]
Diclofenac (DCF)–Carbamazepine (CBZ)–Amoxicillin (AMX)	Pharmaceutical wastewater	EC	Aluminum/Stainless steel	pH = 7.24 CD = 0.3 mA/cm2 Time = 3 h	DCF = 45% CBZ = 40% AMX = 46%	[29]
COD–Chlorides (Cl)–Chromium (Cr)	Tannery	EC	Titanium/Titanium	pH = 8 CD = 12 mA/cm2 Mixing Speed = 780 rpm (M) Volume Reactor = 1.5 L Time = 60 min	COD = 97.96% Cl = 15.92% Cr = 98.23% EEC = 8.05 kWh/m3 OPEX = 5.91 US$/m3	[30]
COD–Chromium–Total nitrogen–Phosphate–Sulfate	Tannery	EC	Aluminum/Aluminum	CD = 1.2 mA/cm2 Time = 25 min Stirring speed = 150 rpm	COD = 84% Chromium = 98% Total nitrogen = 68% Phosphate = 100% Sulfate = 79% EEC = 2.37 kWh/m3	[8]
COD–Turbidity–TDS	Municipal wastewater	EC	Aluminum/Aluminum	pH = 7 COD = 260 mg·L−1 Turbidity (NTU) = 60 Conductivity = 2.4 ms/cm TDS = 1300 mg·L−1	COD = 92.01% Turbidity = 93.97% TDS = 49.78%	[31]
Chromium	Synthetic	EC	Iron/Iron	pH = 4 COD = 43.103 mg·L−1 Cr concentration = 40 mg·L−1 Time = 60 mi	Cr = 99.4% EEC = 1.78 kWh/m3	[32]
COD–Chlorides (Cl)–Chromium (Cr)	Tannery	EC	Copper/Copper	pH = 8 CD = 4 mA/cm2 Mixing Speed = 60 rpm (L) Volume Reactor = 1 L Time = 60 min	COD = 92.24% Cl = 96.45% Cr > 99% EEC = 1.66 kWh/m3 OPEX = 2.62 US$/m3	This study

presents the efficiency rates of various EC technologies in removing heavy metal pollutants from different types of wastewater. This table details the pollutant removal efficiencies and energy consumption requirements under optimal operating conditions. The findings indicate that EC is effective in achieving high heavy metal removal rates across various wastewater streams. Key parameters influencing the removal efficiency include the electrode material, current density, and stirring speed. A critical aspect affecting energy consumption during the treatment process is the selection of electrode material, which also impacts the overall operational costs. The results suggest that exploring different electrode materials, along with reducing the current density, could significantly lower the process costs and enhance the economic viability. For instance, EC using aluminum or iron electrodes demonstrated impressive removal efficiency rates of 80–93% for COD and 84–96% for Cr in tannery wastewater, with energy consumption ranging from 2.37 to 11.42 kWh/m³. In another EC application for tannery wastewater, iron electrodes achieved COD removal efficiency rates of 70–83%, with an energy consumption rate of 3.8 kWh/m³. While EC is proficient in removing suspended particles and heavy metals, its performance in eliminating organic contaminants may be less effective.

From the above, it can be concluded that although Fe/Fe and Ti/Ti electrodes achieved high COD removal efficiency rates, copper electrodes exhibited superior performance, not only in COD removal but also in eliminating specific pollutants such as chromium and chlorides. The consistently high removal rates of these contaminants highlight copper electrodes as a strong alternative to conventional options. In addition, their relatively low operational costs further enhance their practicality for wastewater treatment. Thus, the combination of high pollutant removal efficiency and cost-effectiveness substantiates the claim that copper electrodes represent a valuable option in the electrochemical treatment process.

4. Conclusions

The major objective of this research was to evaluate the effectiveness of the electrocoagulation process by using copper (Cu) as electrodes for tannery wastewater treatment. The study showed that the stirring speed, current density, and reactor volume capacity in the EC process have an evident effect on the removal efficiency. The EC process achieved high removal values for COD, Cl, and Cr in the first ten minutes of the treatment. The study identified the optimum conditions for the EC process as follows: stirring speed = 60 rpm (L), CD = 4 mA/cm², and volume = 1 L. From the process, 92.3% COD removal and 96.5% Cl removal were achieved, and the removal of Cr was nearly complete, achieving an optimum efficiency reaching more than 99%. The operating cost was 2.62 US$/m³, confirming that the use of copper electrodes is more economically feasible than other alternatives. The SEM showed the difference in the copper surface shapes before and after the process, which confirmed the completion of the treatment process. Finally, the copper electrodes showed their worthiness in the EC process as an alternative to conventional electrodes, such as iron and aluminum.