Optimizing electrocoagulation and electro-Fenton process for treating car wash wastewater

Abstract

Background: Car wash wastewater contains several contaminants such as organic matter, oil, grease, detergents and phosphates, all of which are harmful for the environment. In this study, the application of electrocoagulation (EC) to treat car wash wastewater has been studied, and the operating parameters optimized. The electro-Fenton (EF) for further contaminant removal was also investigated. Methods: In EC process, the effect of pH, current density, and the reaction time of the removal efficiency of chemical oxygen demand (COD), phosphate, and turbidity were investigated using the response surface methodology (RSM). The electrochemical cell consisted of four iron electrodes that were connected to a power supply using a monopolar arrangement. In the EF process, the effect of pH, reaction time, and hydrogen peroxide concentration on COD removal efficiency were probed. Results: The optimum pH, current density, and the reaction time for the EC process were 7.3, 4.2 mA cm-2 and 20.3 minutes, respectively. Under these conditions, the COD, phosphate, and turbidity removal percentages were 80.8%, 94.9% and 85.5%, respectively, and the specific energy consumption was 1.5 kWh m-3. For the EF process, the optimum pH, reaction time, current and hydrogen peroxide dosage were 3, 10 minutes, 2 A and 500 mg L-1 , respectively. The EF showed higher COD removal efficiency (85.6%) with a lower specific energy consumption (0.5 kWh m-3) and reaction time compared to the EC. Conclusion: This study shows that both EC and EF can effectively treat car wash wastewater with high removal efficiency within a short reaction time.

Evaluation of the efficiency of electrocoagulation process in removing cyanide, nitrate, turbidity, and chemical oxygen demand from landfill leachate

“…In this study, different parameters such as contact time (10,20,30,40, 50, 60 minutes), pH (5.5, 8.3, 10), current density (11,22,33 mA/cm 2 ), type of electrode (aluminum with lead oxide coating) and 3 replications were investigated. In order to reduce the number of samples and optimize the process, at first the removal efficiency of the process in constant current density with different pH and contact times was investigated.…”

“…In this process, no coagulant chemical is added to the water and the volume of sludge produced in this technology is less than the one produced by the chemical coagulation method (14)(15)(16). Other advantages of electrocoagulation process include absence of toxic residual compounds, removal of various compounds from soluble and insoluble organic pollutants (pesticides, detergents, solvents), soluble inorganic pollutants (heavy metals, nitrate, phosphate, calcium and magnesium), and microbial pathogens elimination (such as bacteria, fungi, viruses) from aqueous environments (17)(18)(19)(20). In this technology, the metal ions produced at the anode electrode (iron or aluminum) react with the hydroxide ions formed at the cathode electrode to form the metal hydroxides.…”

Performance of Combined Electrocoagulation-Advanced Electrochemical Oxidation Used for Oil Field Produced Water Treatment

“…In the EF process, hydroxyl radicals are produced by the reaction between hydrogen peroxide and ferrous ions, which can destroy organic compounds. The reduction of ferric ion to ferrous ion, which can reduce iron sludge production is one advantage of the EF process over the conventional Fenton process [6].…”

“…E110 [6]. pH lower than optimum affects the pollutant removal by producing less hydroxyl radicals, increased scavenging effects of H + and hydroxyl radicals [8].…”

“…The traditional technique of experimental design, in which one process variable is changed, while the other variables are settled, dose not demonstrate the interaction between the process variables. Response surface methodology (RSM) is able to assess this interaction [6]. Response surface methodology finds the optimum values of process variables for a desirable response by using a statistical-based technique to evaluate the simultaneous effects between these variables [16] and [17].…”