Experimental Study On Degradation Of Micro Pollutants In Source Water By Centrifugal Pump Hydraulic Cavitation

Tetracycline（TET）is a kind of micro pollutant in water environment,which has stability and biodegradability.At present,some scholars have used ultrasonic cavitation to remove tetracycline,but the efficiency of ultrasonic cavitation reactor is low.As a new technology to deal with micro pollutants,hydraulic cavitation has gained more and more attention.At present,the degradation of pollutants by hydraulic cavitation focuses on jet cavitation.The existing research results show that the effect of centrifugal pump is better than that of jet cavitation and eddy current cavitation.In this paper,based on the self-made hydraulic cavitation device,the degradation effect of tetracycline by centrifugal pump before and after the installation of orifice plate cavitation device was compared,and the degradation effect of centrifugal pump in operation was also analyzed;The effects of five kinds of centrifugal pump pressure,five kinds of initial concentration,five kinds of p H value,cavitation time and temperature on the degradation effect were investigated by single factor method,and the optimum working conditions were determined by orthogonal test;the synergistic effect of hydrogen peroxide（H₂O₂）and centrifugal pump cavitation was tested;The kinetic characteristics of the degradation process were analyzed.The main achievements are as follows:（1）The optimal parameters before and after installing orifice plate cavitator in centrifugal pump:the outlet pressure of centrifugal pump is 0.25 MPa,the initial concentration of tetracycline is 3 mg/L,the p H value is 3.0,and the cavitation time is 4h.Under these conditions,the corresponding degradation rates were 29.88%and 35.2%respectively,and the degradation effect was the best when the temperature was 40℃.（2）The results showed that the degradation rate curve accorded with the first-order kinetic characteristics when the device ran for 0-180 min,and accorded with the second-order kinetic characteristics when the device ran for 0-300 min.The content of OH radical played a leading role in the degradation of tetracycline.（3）The results showed that hydrogen peroxide and hydraulic cavitation had obvious synergistic effect,and the combined degradation rate increased from 22.77%and 27.04%to65.2%and 68.88%respectively.The degradation of 3 mg/L tetracycline solution had the best condition as above,and the best condition showed up when the dosage of 30%hydrogen peroxide solution was 0.3L.The degradation rates of tetracycline were 73.23%and 80.04%respectively.（4）When tetracycline was degraded,the degradation effect of the centrifugal pump with orifice generator was less than 10%.The cavitation effect was mainly hydraulic cavitation of the centrifugal pump,and the energy consumption in the operation of the device mainly came from the centrifugal pump.