Shearing Strength Distribution And Mass Transfer Enhancement Of Vortex Wave Membrane Bioreactor

In order to enhance performance of mass transfer, the vortex wave MBR can be used as a novel technic. It combines vortex wave flow and MBR technic, which using vortex wave can generate very effective local mixing and come into being forced convection, expedite momentum exchange under the condition of laminar flow with low Re number. Compared with traditional methods of enhancing mass transfer by using turbulent flow, the shearing stress and the power dissipation in the vortex wave MBR are rather low. It is very worthy, which increases survival rate of microorganism cells and can also solve some problems such as clogging and concentration polarization in the traditional MBR.In this paper, the parameters of mass transfer performance are experimentally tested in the vortex wave MBR, and the distribution of shearing strength in the vortex wave MBR is investigated by using numerical simulation method. The following contents are discussed.A set of experimental equipment of vortex wave MBR is established, which is sequence reactor. The mass transfer experiments of water and synthesis wastewater are carried out for different channel structures. The mass transfer performance and the results of wastewater treatment are evaluated by chemical oxygen demand (COD) of influent and effluent. Some experimental results are obtained: â‘  Vortex wave flow may remarkably enhance gas-liquid mass transfer, and the overall volumetric mass transfer coefficient (k_La) averagely increases 26.67% comparing with that of the steady flow. â‘¡ Mass transfer can be further enhanced by reducing deflector spacing L in the channel. The relation between L and k_La can be described as following: k_La(%)= -14.537Ln(L)+79.846. â‘¢ The Re number has an important effect to k_La in all kinds of channel structures. Based on the above research results, the mechanism of significant mass transfer enhancement under laminar flow conditions is analyzed.The numerical simulation of two-phase flow field in the reactor is carried out in this paper. The distribution of shearing strength in the channel is systematically obtained: â‘  The shearrates of wall, vortexcore, vorticity and non-vorticity regions are descending sort. â‘¡ With Re number increasing, the average of shearing strength becomes linearly increasing tendency in the back step expand channel.This paper quantitatively studies the mass transfer characteristic of the vortex wave with low Re number. It provides experimental and design foundation for further study andindustrialization of the vortex wave MBR.