An Experimental Study Of Degradation Of Refractory Wastewater By Hydrodynamic Cavitation Due To Triangular Orifices Plates

Hydrodynamic cavitation has made certain progress in many areas since it becomes a hot topic. The collapsed cavitation bubbles resulting in the generation of microjet and shock wave can release tremendous amounts of energy in a short time and the local extreme high temperature and pressure generated by bubble collapse in cavitation can induce rupture of chemical bond of water and occurrence of free hydroxyl radical·OH and H2O2. Hydroxyl radical has the ability of strong oxidation. Based on these special phenomena, hydrodynamic cavitation has been used in wastewater treatment research as a new technique. Hydrodynamic cavitation technology has many advantages, such as reaction device simple, no need to add any reagent, no secondary pollution, low operation and maintenance costs and large-scale production run. In recent years, more and more domestic and foreign scholars began to study hydrodynamic cavitation technology. This paper carried out the pilot study of degradation of refractory wastewater by the self-developed hydrodynamic cavitation due to triangular orifices plates. The device was designed and built in the Hydraulics Laboratory at Zhe Jiang University of Technology. The main research works are as follows:(1) Study hydrodynamic cavitation characteristics of the device. Probe the influence of factors such as porosity, inlet pressure, flow rate and back pressure on cavitation number. Observe the change of pressure behind of the orifices plates and find out the region of maximum pressure recovery occurring.(2) Select methylene blue to capture hydroxyl radicals generated by the device. Detect the number of oxidant and reflect hydrodynamic cavitation intensity of the device.(3) Choose P-NP as the target pollutant to research the degradation of refractory pollutants. Discuss the influence of factors such as run time, initial concentration, pH and back pressure on the degradation of P-NP. Provide a new processing possibility for phenolic wastewater.(4) Study the treatment of practical printing and dyeing wastewater in the hydrodynamic cavitation device. Detect the degradation of COD and color. Discuss the influence of factors such as run time, initial concentration and pH on the processing effect.