Numerical simulation of oxidation ditch for wastewater treatment

摘要

Shortage of available water resource and pollution of water resource is an urgent problem confronted by Chinese people. Towards this, the equipment for wastewater treatment must be improved and optimized. Oxidation ditch plays a vital role in wastewater treatment. For the sake of making oxidation ditch more efficient, it is necessary to study on the optimization of oxidation ditch. The flow dynamic character is an important parameter for the design and optimization of the reactor. Since the flow dynamics of oxidation ditch will change with the structure of the ditch, the simulation should be performed accordingly. Thus we optimize the oxidation ditch with the help of computational fluid dynamics (CFD) in this paper. It is suggested that there are solid and liquid two phases in the oxidation ditch and the mixture model is used. The simulations are limited to three-dimensional, steady state simulation in a turbulent flow regime. Standard k-ε model is employed to simulate the turbulent flow. By simulation, the velocities and volume fractions of solid and liquid phase, the static pressure in the oxidation ditch are obtained. The influence of aerator speed on distribution of velocity and solid concentration in oxidation ditch is investigated. The results supply useful reference information for pilot-scale study and enlargement design.