Study On The Application Of Hydrodynamic Cavitation Technology In Treatment Of Tetracycline Wastewater

Tetracycline antibiotic is one of the most common antibiotics in production and usage worldwide due to their low price and broad-spectrum bactericidal properties.Therefore,a large number of tetracycline-containing wastewater is produced.Tetracycline wastewater untreated or incompletely treated enters the environment,posing potential risks to human health and the environment.For example,producing drug-resistant bacteria,affecting microorganisms in the environment,destroying balance of nature,threatening human health,etc.At present,there are many methods to treat tetracycline wastewater,but the degradation efficiency of tetracycline is not high because of its low biological absorption and difficult degradation.Therefore,it is of great value to explore efficient ways to treat tetracycline antibiotic wastewater.Hydrodynamic cavitation is a promising technology for organic pollutant degradation.It has the advantages of simple and cheap installation,good degradation effect,low energy consumption,no secondary pollution and green environmental protection,which has been widely concerned in recent years.In this paper,the degradation of tetracycline in water on hydrodynamic cavitation technology was studied by using self-made hydrodynamic cavitation device,and the various factors affecting the degradation of tetracycline were also investigated,which provided a new method for the effective treatment of tetracycline wastewater.（1）Three sets of venturi tudes with different geometric parameters were used to degrade tetracycline hydrochloride,to determine the best geometric parameters of the venturi tude,making the zetetic experiment for subsequent processing.The experimental results showed that the venturi tube with the half convergent angle of22°,the throat length of 2.0 mm and the half divergent angle of 6°has the optimal hydrodynamic cavitation effect.Under these conditions,the highest degradation ratio of tetracycline was 82.22%at 150 min.（2）The venturi tube with the optimal geometric parameter was used as the hydrodynamic cavitation generator to degrade tetracycline hydrochloride in solution.The influences of inlet pressure,initial concentration of tetracycline,initial p H and common anions in surface water on the tetracycline degradation ratios were analyzed in order to optimize hydrodynamic cavitation degradation conditions.It was found that the highest degradation ratio（83.17%）could be obtained when the inlet pressure was 3 bar and the initial concentration of tetracycline was 5.0 mg/L.The acidic condition was helpful to the degradation of tetracycline on hydrodynamic cavitation.When the initial p H value was 3.0,the degradation ratio was 77.24%.The presence of CO₃^2-in solution could obviously promoted the hydrodynamic cavitation degradation of tetracycline,while the presence of NO₃^-and SO₄^2-inhibited the hydrodynamic cavitation degradation of tetracycline.（3）In order to further improve the degradation effect of tetracycline,HC-Fenton technology was used to treat tetracycline solution,and the effects of Fe²⁺and H₂O₂concentration on the degradation ratios of tetracycline were investigated under the same conditions.The results showed that HC-Fenton technology enhanced the degradation of tetracycline.When the concentration of Fe²⁺was 5.0 mg/L and H₂O₂was 10 mg/L,the degradation ratio of tetracycline was the highest,reaching 95.48%.The degradation process of tetracycline by HC-Fenton was consistent with the first order chemical kinetics.（4）The possible degradation mechanism of tetracycline on hydrodynamic cavitation was discussed.The mineralization degree of tetracycline was analyzed by TOC,and the degradation products in the process of tetracycline degradation by hydrodynamic cavitation were identified by LC-MS.The results showed that tetracycline was effectively mineralized under the action of hydrodynamic cavitation.By the attack of·OH,tetracycline molecules were hydroxylated,ring-opening and ring-removing functional groups,which were decomposed into a series of low molecular weight organic compounds,and could be further oxidized into CO₂,H₂O and some inorganic ions such as NO₃^-.This study provides evidence that hydrodynamic cavitation can be used to treat tetracycline antibiotic wastewater on a large scale.