Study on the treatment of Cu²⁺-organic compound wastewater by electro-Fenton coupled pulsed AC coagulation

Electro-Fenton (EF) coupled with Pulsed alternating current coagulation (PACC) is an effective technology for the treatment of Cu²⁺-organic wastewater. In this study, the removal efficiency (R_e), electrical energy consumption (EEC) and removal mechanism of Cu²⁺-organic were analyzed and the optimal operation parameters were determined. SEM, EDS, XRD and FTIR were used to characterize the morphology, elemental composition, crystal structure, function groups of sludge produced in the EF-PACC. UV, ESR and GC-MS were employed to determine concentration of organic matter, existence of OH, middle products of decomposed organic matter in EF-PACC, respectively. The results show that under the optimal conditions of initial pH = 2.5, current density (j) = 2 A/m², initial c(Cu²⁺) = 50 mg/L, c(chemical oxygen demand, COD) = 500 mg/L, c[H₂O₂] = 10 mL/L, frequency (f) = 1 Hz, t = 20 min, the R_e(Cu²⁺) can reach 99.59%. R_e(COD) is 90.21%, EEC 1.695 × 10^-1 kWh/m³, and the amount of produced sludge (W_s) is 0.9283 kg/m³. Compared with single EF and PACC processes, the order of treatment efficiency is EF-PACC > EF > PACC. EF-PACC technique was a highly effective method in the treatment of Cu²⁺-organic compound wastewater. The EF-PACC coupled process includes that electrolyzed Fe³⁺ produces electrocoagulation and OH produces degradation of organic compounds. The combined action of the two effects can effectively remove Cu²⁺-organic from wastewater.