Study On High-efficiency Co-coagulation Floatation Separation Method And Device

It is very necessary to improve the performance of co-coagulation floatation device due to its shortcomings,such as long reaction time,poor purification effect.Therefore,in this study,a high-efficiency co-coagulation floatation separation device is designed based on the principle of air flotation.The operation conditions of the designed equipment was further optimized through experiments,including coagulation and air flotation.The domestic sewage is used as the raw water to optimize the operation conditions of the coagulation and air flotation experiments.The COD concentration,SS concentration,and PH value of the raw water is about 340-360mg/L,200-220mg/L,and 6-8,respectively.The first-stage coagulation orthogonal test determined that the best type of coagulant is PAC,the optimal dosage of coagulant is 300mg/L,the optimal dosage of coagulant PAM was 4mg/L,and the suitable pH value is 7.0.Contrast experiments(PAM+PAC vs.PAC)are conducted to highlight the importance of PAM in coagulation tests.The results of the orthogonal test of coagulation were verified by the optimal dosage of PAC,which were basically consistent with the results of the orthogonal test.The operating conditions of the air-floating stage were optimized by using the coagulation air-floating static device.The optimal dissolved gas pressure(evaluated by the bubble diameter)and reflux ratio were determined to be 0.5 MPa and 30%,respectively.On the basis of previous results,the best purification effect can be achieved by adopting the secondary coagulation method and stepwise adding the gas dissolved water.For example,the removal rate of COD and SS can reach 82.7%,and 94.1%,respectively.The reserved inlet port 2 of gas dissolved water and inlet port 1 of PAM in the copolymerization air flotation separation device was finally determined based on the removal rate of COD and SS.Contrast experiments were conducted using this device to compare the process of copolymerization flotation and coagulation-sedimentation.The results show that the best dosage of PAC of copolymerization flotation is 60mg/L less than that of coagulation-sedimentation process.Meanwhile,shorter flocculation time and better the purification effect can be achieved using copolymerization flotation.For high concentration water samples,the copolymerization floatation process possesses stronger shock resistance.