Experimental Study On Degradation Of Refractory Wastewater By Hydrodynamic Cavitation Due To Square Orifices Plates

In water treatment, the hydrodynamic cavitation technology as a new method of harnessing refractory wastewater, not only removes toxic substances effectively, but also shows many other advantages including effective degradation, energy saving, high efficiency and simple reaction device.In this paper, degradation on refractory wastewater was studied by the square orifices plate as the generating device of hydrodynamic cavitation, which was designed in the Hydraulics Laboratory of Zhejiang University of Technology. At first, the influences of the opening ratio of the multi-orifice plate, cavitation number, back pressure of cavitation, hydraulic radius, initial concentration of p-nitrophenol and pH value on degradation of p-nitrophenol were explored by using the advanced experimental facilities in the hydraulics laboratory at Zhejiang University of Technology. On this basis, the impact of pressure characteristics and resistance characteristics were studied. In order to explore the cavitation mechanism and find the best element which can enhance the cavitation phenomenon. We used the solution of methylene blue as the medium to capture the production of·OH radicals due to hydrodynamic cavitation and performed quantitative analysis by uv-vis spectrophotometer. To verify the results, degradation on actual wastewater (Atrazine wastewater) was studied. We explored the influences of initial concentration of atrazine wastewater, running time and orifices plate characteristics, and found out the best orifices plate in processing atrazine wastewater by experiment.This study results could provide a reference for a design of multiple-orifice plate, and laid a foundation for the development and utilization of the cavitation.