As a result of industrial development, many types of waste are generated, some of which are discharged into water, causing water pollution and having a negative impact on life. The electro-Fenton process (EF) has verified high efficiency in treating pollutants with low cost, ease of handling and operation, and this technology is one of the more efficient advanced oxidation technologies. The main objective of this present work is to explore the efficiency of a three-dimensional Electro-Fenton system (3DEF) in removing eosin, methylene blue, and methylene violet from simulated wastewater using graphite as anode, nickel foam as the cathode, and alum sludge as the third particle and as the source of catalyst. The study investigated the effect of operating parameters such as current density, J, catalyst concentration, and Na2SO4 concentration as supporting electrolyte, at a pH of 3, a temperature of (28 ±1) °C, an air flow rate of 20 L/h, and a treatment time of 30 minutes. Response surface methodology (RSM) was used to design and analyse experimental data. Based on the results of RSM, the best removal efficiency was achieved at J = 4.2 mA/cm2, [Fe2+] = 0.2 mM, and [Na2SO4] = 0.05 M, where the Re and chemical oxygen demand (COD) removal was 95.76 % and 100 %, respectively. The alum sludge was a very excellent choice as a primary source of Fe catalyst and the 3DEF process is an effective system that can eliminate many types of dyes.
