Study Of Aerobic Granular Sludge Integrated Industrial Reactor

Aerobic granular sludge is a granular sludge formed by the interaction of microorganism itself under the action of suitable hydraulic shear force and annular flow field.With the advantages of compact biological structure,fast settling speed and strong impact resistance,aerobic granular sludge water purification technology has attracted wide attention.At present,aerobic granular sludge is mainly cultivated in a cylindrical reactor with large diameter to diameter ratio.The cylindrical reactor with large height to diameter ratio has difficulties in construction and low single cycle treatment,which makes it difficult to apply aerobic granular sludge to industrial application.Therefore,it is of great significance to design a kind of aerobic granular sludge industrial reactor with easy construction and large amount of treatment' to promote the industrial application of aerobic granular sludge technology.Therefore,a design scheme of integrated industrial reactor for aerobic granular sludge using a positive four prism reactor as a unit is proposed.The flow field characteristics of positive four prism and cylindrical reactor were compared by using CFD numerical simulation method.The results show that the two reactors have similar characteristics in the gas phase,the velocity distribution of the liquid phase and the axial flow velocity along the radial direction.It is proved that the internal flow field of the four prism reactor is similar to the cylindrical reactor.Using visualization technology and PIV technology,the experimental study of gas-liquid two-phase flow in two reactors was carried out.The results show that the gas flow field in the two reactors is similar.The gas phase flow field rises spirally from the bottom of the reactor around the center axis,and with the elevation,the gas phase moves gradually to the vertical rise.The experimental results agree with the simulation results.In the process of gas rising,the bubble size increases faster in the bottom area of the reactor.With the increase of axial height,the bubble increases slowly.In the liquid phase flow field,the liquid velocity field of the two reactors is similar to the axial liquid velocity distribution,and the flow field in the flow field has obvious annular flow field which is beneficial to the formation of the granular sludge.It is proved that the positive four prism reactor has the condition of the flow field of aerobic granular sludge.The amplification criterion of an aerobic granular sludge reactor is determined.The criterion is based on the characteristic quantity of the liquid phase velocity ratio and determines the effectiveness of the reactor magnification.By using the CFD numerical simulation method,the validity of the amplification criterion is verified by studying the flow field characteristics in the reactor before and after amplification.The results show that there are similar gas phase flow field and liquid velocity field distribution in the two reactors before and after enlargement.In the same characteristic position in the reactor,the liquid velocity ratio satisfies the calculation formula of the amplification criterion,which proves that the criterion can verify the effectiveness of the aerobic granular sludge reactor amplification.A design scheme of aerobic granular sludge integrated reactor is proposed,and its structural parameters and aeration system are designed.The aeration uniformity is used as the evaluation standard,and the aeration system is evaluated and optimized.At last,by using the analytic hierarchy process(AHP)to satisfy the application of industrialization,the comprehensive effectiveness of the design scheme of aeration system is evaluated,and the design scheme of the best comprehensive efficiency and the most suitable for industrial application is determined.