| Air flotation process was a high-efficiency solid-liquid separation process commonly used in water treatment.The combination of microbubbles and floc particles was the basis for achieving solid-liquid separation.Most of the current research is aimed at the improvement of air flotation reactors and technological improvements.At present,there is not much microscopic exploration of air flotation technology.In order to solve the problem of improving air flotation efficiency from a micro perspective,this study constructed a dynamic observation system of simulated flocs,explored the distribution law of bubble size and number of bubbles in the air flotation process under different floe sizes,and revealed the processing characteristics of the air flotation process The combined characteristics with airborne flocs provide important theoretical and practical significance for improving the efficiency of solid-liquid separation in air floatation process and optimizing the dosage of coagulant.The main research results of the study are as follows:In this study,montmorillonite and silica were used as two typical inorganic suspension systems,and the treatment characteristics of typical inorganic suspension by air floatation process were explored.For montmorillonite system,when the dosage of coagulant is greater than 80mg·L-1,the turbidity removal rate is stable at about 60-70%,while the dosage of coagulant in silica system is higher than 400mg·L-1,the turbidity removal rate was only stable at about 40%.Under the optimal dosage of coagulant,the airborne floe size of the two types of inorganic suspension system was concentrated at500-750?m.Since the surface of silica is more negatively charged than montmorillonite,when the amount of coagulant added is small,the positively charged polynuclear hydroxyl hydrolysate formed by coagulant hydrolysis is insufficient to neutralize the surface of silica colloidal particles or bubbles Negative charge,so the dosage of coagulant required to achieve the best turbidity removal rate is higher.Based on the scale distribution of the airborne flocs of the two inorganic suspended matter systems above,the simulated flocs with diameters of 0.35 mm,0.5mm,0.75 mm,1mm and 1.5mm were selected to analyze the binding characteristics of the flocs and bubbles.The results showed that: The size and number of bubbles attached to the simulated flocs increase with depth.The larger the simulated floe size,the larger the proportion of small bubbles,and the airborne flotation efficiency(airborne floc buoyancy / volume)It shows the characteristics of increasing first and then tending to stability over time,and the air flotation efficiency is inversely proportional to the floc diameter,that is,the smaller the floc size,the higher the air flotation efficiency. |
PDF Full Text Request