Experiments And Mechanism Study On Microbubble Air Floatation And Waste Liquid Circulation Enhancement Fenton Oxidation

The chemical industry occupies an important position in my country's national economy.In the chemical production process,a large amount of complex and difficult-to-degrade process wastewater will be produced,it is an urgent problem to be solved in the chemical industry for economic and effective treatment of wastewater.The air floatation method has the characteristics of high separation efficiency,short residence time,low operating cost,and can effectively remove suspended solids,oily substances and other pollutants in wastewater.The Fenton oxidation method has strong oxidizing property and is suitable for oxidative degradation of high-concentration refractory organic wastewater.This article combines the characteristics of microbubble air floatation technology and Fenton oxidation technology,proposes the use of microbubble air floatation based on circulating fluidization oxidation technology,develops microbubble air floatation based on circulating fluidization oxidation device,and uses this device to process perfume production Process wastewater.The conventional Fenton oxidation method was used to treat the wastewater from the fragrance production process,the initial pH=3.0,the dosage of H₂O₂?30%?was 36 mL/L,the[Fe²⁺]/[H₂O₂]mass ratio was 0.12,and the reaction time was 40min.The COD removal rate is 50.21%.It adopts Fenton oxidation-microbubble air floatation combined process to process,at an inlet pressure of 0.06 MPa,an air inlet rate of 90 mL/min,the dosage of H₂O₂?30%?is 36 mL/L,[Fe²⁺]/[H₂O₂]mass ratio under the condition of 0.12 and reaction time of 40 min,the COD removal rate reached 63.41%,and the COD removal rate increased by 13.2 percentage points.The experimental results of microbubble air floatation treatment show that the single jet air entrainment method is used to manufacture microbubble,the average diameter of microbubble is between 154.40 and 373.60?m,and the average diameter of microbubble is larger.Using this method to produce microbubbles for air flotation enhancement treatment of wastewater from fragrance production process,the COD removal rate is between 50.08%and 69.81%,and as the average value of microbubbles gradually decreases,the COD removal rate gradually increases.When the average diameter of microbubbles is 154.40?m,the COD removal rate of wastewater is as high as 69.81%,the microbubbles are manufactured by a single dissolved gas precipitation method,the average diameter of microbubbles is between73.42⁹4.38?m,and the average diameter of microbubbles is small.Using this method to manufacture microbubbles for air flotation enhancement treatment of perfume production process wastewater,COD removal is between 68.21%and 76.4%,the COD removal effect is high,and as the average diameter of microbubbles gradually decreases,the COD removal rate gradually increases.When the average diameter of microbubbles is 94.38?m,the COD removal rate of wastewater reaches a maximum of 76.4%,the microbubble is manufactured by the coupling method of jet air entrainment and dissolved gas precipitation,and the average diameter of microbubbles is between 100.13¹09.40?m.Using this method to produce microbubbles for air flotation enhancement treatment of perfume production process wastewater,COD removal rate is above 79.3%.When the average diameter of microbubbles is 101.08?m,the COD removal rate of wastewater is as high as 82.01%,the corresponding jet pressure P₁=0.03 MPa,dissolved gas pressure P₂=0.01 MPa.A mathematical model of microbubble size control between D₁₀?average microbubble diameter?and P₁?jet pressure?and P₂?dissolved gas pressure?was established.When there is no waste liquid circulation,the COD removal rate of wastewater is12.7%.Using the waste liquid circulation method,the wastewater COD removal rate will be greatly improved,and as the cycle treatment time is extended,the wastewater COD removal rate will gradually increase.When the circulating treatment time was increased from 10 min to 40 min,the wastewater COD removal rate increased from48.7%to 82.01%,an increase of 33.31 percentage points.Particle imaging velocimetry?PIV?was used to test the flow field in the reaction zone and separation zone of the device.The test results show that the flow field has strong turbulence intensity near the reaction zone of the device,which is conducive to the dispersion and mixing of agents.At a height of z=75 mm from the bottom of the reactor,the axial velocity of the fluid is large and the direction is downward.In this process,the fluid will have a strong impact with the bottom plate,and the fluid will have a countercurrent collision and shear action,which also promotes Dispersion and mixing of medicaments.In the vicinity of the separation area of the reaction device,the fluid velocity near this area is relatively uniform and stable,which is conducive to the separation of the pollutants carried by the microbubbles from the wastewater.