1. Electric Fenton process technologyPrinciple
The reaction principle of the electric Fenton process is based on the mechanism of action of the traditional Fenton reagent, using the electrolytic plate to produce new ecological H2O2 and Fe2+, and at the same time the reaction produces strong oxidizing ·OH, and the organic matter in the reaction system undergoes rapid oxidation reaction and free radical chain reaction under the action of ·OH, so that the COD in the wastewater is removed. The electrochemical production of H2O2 is generated by the reduction of oxygen under the condition of cathode oxygenation or aeration, and Fe2+ can also be obtained by the reduction reaction of the cathode.
Under acidic conditions, oxygen undergoes a 2E reduction reaction at the cathode by oxygenation or aeration, as shown in the following equation, to produce H2O2. In this process, oxygen is first dissolved in solution and then migrates to the surface of the cathode in solution, where it is reduced to H2O2.
o2 + 2h+ +2e → h2o2
For the electric Fenton reaction, pH is one of the important influencing factors. At a pH of 2At 8, the [·OH] produced from the Fenton reaction is maximum, therefore, in an electric Fenton reaction with Fe2+ as the catalyst, the condition for pH is usually chosen is 3.
Features of the electric Fenton process:
1. The electric Fenton process does not need to prepare ferrous sulfate solution, which saves water resources and chemical costs.
2. Control the concentration of ferrous ions in the solution by controlling the voltage or current, which is simple to operate and easier to automate.
3. The treatment efficiency is higher, and the ferrous ions near the electroelectric Fenton plate are highly enriched, which has a higher reaction impetus than the traditional Fenton, and the reaction time is greatly shortened.
4. The traditional Fenton ferrous ions** are added to the ferrous sulfate, and after the effluent is flocculated and precipitated by alkali adjustment, the sulfate remains in the water in the form of sulfate, which will increase the salt content of the effluent; The electric Fenton ferrous ions are supplied by the iron plates and do not increase the sulfate ions, so they have less impact on subsequent biochemical treatment and wastewater discharge.
5. Hydrogen peroxide H2O2 and free radical·OH will be produced in the electrolytic reduction process, and at the same time, there is a new ecological Fe2+ production, and the catalytic effect of hydrogen peroxide H2O2 will not be weakened, so the dosage of hydrogen peroxide H2O2 in the treatment process is reduced to the greatest extent, thereby reducing the operating cost.
6. The pH of electric Fenton effluent is about 8, and the pH of traditional Fenton effluent is 5 6, and the amount of alkali used in electric Fenton is less when adjusting alkali flocculation and precipitation.
7. In addition to the oxidation of hydroxyl radicals generated near the anode, the cathode also has a reducing effect, and heavy metal ions can be precipitated and precipitated at the cathode, so as to be removed.
Second, the structure of the equipment
The complete set of equipment is composed of four parts: electrolyzer, electrode material, supporting DC power supply and auxiliary equipment. The electrolyzer box is made of corrosion-resistant PP material or "carbon steel + anti-corrosion" material, electrode plates are placed inside, and the supporting DC power supply converts 380V AC power into DC power. The auxiliary equipment is configured by the user according to his needs, including water pumps, air pumps, pipelines, valves, coagulation reactors, etc.
Three, equipment installationDebuggingDescription
1. Place the electrolytic cell on a stable and firm flat foundation, and connect the inlet and outlet pipes.
2. Connect water, gas and dosing pipelines according to the designed process.
3. Place the DC power supply in the designated position next to the electrolyzer, and pay attention to the waterproof, anti-collision and anti-discharge of the power supply.
4. Connect the cathode and anode of the plate to the corresponding output copper bar of the power supply. Due to the large working current of the equipment, it is necessary to ensure that the connection points are in reliable contact, and there is no flashover and obvious heating at the wiring.
5. Connect the input power cord of the DC power supply to 380V AC.
FourInstructions on equipment debugging and use
1. Operation process.
Open the inlet and outlet valves, start the inlet pump, acid dosing device and hydrogen peroxide dosing device, and pump the treated wastewater with pH adjustment of about 3 and mixed hydrogen peroxide into the electrolyzer. Adjust the opening of the valve, control the inlet flow, and ensure that the residence time of the wastewater in the tank meets the design requirements; After the equipment is filled with wastewater, turn on the aeration device, turn on the power supply and adjust the power supply parameters. Regularly sample and analyze from the water outlet, and adjust the amount of hydrogen peroxide added according to the water quality of the effluent.
2. Power output adjustment.
Turn on the incoming switch of the power supply, turn on the DC switch on the controller, and wait for 5 seconds. Slowly rotate the adjustment knob clockwise to increase the output and observe the current and voltage values. In the working mode of steady flow, the output current is adjusted to the required value, and the voltage will be automatically adjusted around a certain value according to the conductivity of the wastewater, and the data will be recorded regularly.
It is recommended that the three-dimensional electrolysis treatment time is 60min, and the specific residence time is determined according to the raw water quality and process requirements.
3. Shut down. 1) Turn the output knob on the power control panel to the minimum and turn off the DC power switch.
2) Turn off the AC input switch of the power supply.
3) Turn off the inlet pump, aeration device, and cut off the main power switch.
4. Precautions in the use process.
After the equipment is put into use, it should be ensured that the plates and fillers are submerged in water when the machine is shut down to prevent the poles.
Plates and fillers are oxidized and corroded in the air, reducing service life.
FiveequipmentAbnormal situation and troubleshooting
1. The water temperature will increase during operation, if the water temperature in the tank is greater than 60, the current and voltage should be appropriately reduced.
2. When adjusting the current, if the current does not increase much, but the voltage value is high, it means wastewater
The conductivity is not good, and it is necessary to improve the conductivity of wastewater, such as adding substances such as NaCl or acid, and not blindly and directly increasing the current.
3. During operation, if the current value is abnormally large, there may be a short circuit of the equipment, and the machine should be stopped immediately for inspection and solution.
4. If the blistering in the reaction tank is serious during operation, the aeration volume should be reduced or the aeration device should be started and stopped regularly, and if it cannot be solved, the defoamer can be appropriately added to the raw water.