Patent ID: 8273249

Claim:
A method of integrating electrochemical oxidation and flocculation processes for pre-treatment of coking wastewater, comprises steps as follow: (1) Leading high-concentration coking wastewater into a reaction pool; adding acidic solution into the wastewater to adjust its pH to 6-8, then adding ferrous sulfate as a catalyst; (2) Leading wastewater treated by Step (1) through parallel plate electrodes wherein the wastewater is treated by pulsed high-voltage electric field with the following working parameters: leading-edge rise time of 40-50 ns, pulse breadth of 50-300 ns, electric field strength of 20-50 kv/cm, repetition frequency of 40-240 pps, and acting time of 1-180 s; (3) Leading wastewater treated by Step (2) through another set of parallel plate electrodes wherein the wastewater is treated by pulsed high-frequency DC electrolysis with the following working parameters: pulse frequency 0.8 MHz-20 MHz, current density at electrolytic oxidation area of 200-1000 A/m 2 , cathode-anode phase change time of 1-120 minutes, and electrolytic area retention time of 0.5-1 hour; (4) Further treatment of the wastewater after Step (3) with microbubble oxidation process wherein alkali is added into wastewater to adjust the pH to 8-9; then polyacrylamide is added into wastewater as a coagulant aid; keeping wastewater at this reaction area for 5-20 minutes and then leaving the wastewater for natural precipitation for 4-6 hours; wastewater so treated is eligible for later routine biochemical treatment.