Numerical Simulation Of Integrated Oxygen-Artificial Floating Island Integrated Repair Of Polluted Water

Remediating polluted water with integrated mixing-oxygenation and artificial floating island was numerically investigated,it is found that this technology could effectively enhance the fluidity of water,increase the dissolved oxygen content,and significantly reduce the organic pollutants in water.In order to better evaluate the water purification performance with this integrated device and improve the efficiency of the integrated device,the structural parameters of the integrated device were optimized with the help of FLUENT software,and the remediation performance of the artificial floating island was simulated with MIKE3 software.The research outcome will provide guidance for the application of this integrated device.（1）The numerical method based on Fluent was developed to simulate the flow around the mixing and vacumm oxygenation device,and the simulation results were verified against the measured data.After confirming the accuracy and reliability of the numerical simulation method,a series of process parameters of the device were set for the orthogonal numerical simulation research,and the best mixing-oxygenation performance of the device was achieved under the following optimal parameters:the shrinkage ratio is 0.6,the diffusion inclination angle is 15°,and the distance between the outer edge of the impeller and the diffusion side wall is 30 cm.When the throat contraction ratioγ<0.6,the flow velocity and pressure in the device are asymmetrically distributed,and the critical Reynolds number of the asymmetric flow in the device was dependent on the structural parameters.The diffusion dip angle had little effect on the water-lifting performance of the device,but had a great influence on the oxygenation performance of the device.The distance r between the impeller and the diffusing side wall was negatively correlated to the water-lifting performance,but the influence is weak,reflow strength and reflux rate of the recirculation zone increased with the increase of the value of distance r.（2）Using the Morris parameter screening method,the first-order parameter sensitivity analysis of numerical simulation model for remediating polluted water with the mixing-oxygenation and artificial floating island was carried out,and the strong sensitivity parameters and insensitive parameters of each water quality index were determined,and the parameter sensitivity was quantitatively analyzed based on the RSMSobol method.The degree of influencing the simulated results for each water quality index were determined when the parameters interacted together,which plays a guiding role in calibrating the model parameters.（3）When running the integrated device of mixing-oxygenation and ecological floating island,the dissolved oxygen level in the water body could be effectively improved,and large amount of organic matter in the water could be degraded by ecological restoration.The simulated results showed,under similar initial water quality conditions,the natural removal rates of BOD₅ and NH₄⁺-N in one week were about 28%and 59%,respevtively,but the removal rates of BOD₅ and NH₄⁺-N were increased to48%and 66%with the operation of this device,among which the removal rates of BOD₅ and NH₄⁺-N by the ecological floating island were 60%and 84%.