Application Study Of Particulate Separation Principle Of Dean Vortices In The Treatment Of Secondary Effluent

Flocculate sedimentation, dielectrophoresis, immunomagnetic, membrane separation and hydrodynamic separation were some traditional techniques of particle separation. There were some advantages and disadvantages. Membrane separation was one of most widely used,which was restricted to the conditions of concentration polarization and membrane pollution. Particle separation principle on laminar Dean vortex has been applied in the areas such as power. Particulate separation principle,which produced by Dean vortices of the formation of the bend laminar flow,was applied to the treatment of secondary effluent. Separation device was developed rely on fluid power for replace membrane separation technique.HDS(Hydrodynamic Separation)was developed by numerical simulation and design in the channel. According to the flow length and height,HDS was divided into the whole circle of 1.1 mm, the whole circle of 1.0 mm and semicircle of 1.0 mm That was designed hydrodynamic separation device by experiments with water of cocoanut charcoal and the river with moderate flocculants. The effect of separation on particle size distributions,different flow velocity,dosage of flocculants and length of the pipe was investigated Through the simulation experiments and analysis,the result were shown as following:①SS removal rate was over 90% by 1.1mm and 1.0mm HDS-whole circular device in the experiment of cocoanut charcoal. SS removal rate was about 75% by 1.0mm HDS-semicircular device. And the effect of separation was best by 1.1mm HDS-whole circular device. The effect of separation was best while influent particle sizes were between 94.6um and 161.4um.②In the Coagulation-HDS experiment, the effect of separation was enhanced as the flow velocity increases when the flow was under 600 m L/min,the effect remained stable when the flow was over 600 m L/min. The turbidity,TP and SS removal rate was over 90%,85% and 50% by 1.1mm HDS-whole circular device when the flow was 600 m L/min. After the secondary effluent was separated through the device,the turbidity of clean water was about 1NTU.HDS was good applied to the treatment of secondary effluent.③The flocculating particles were relatively dense and large, which were formed byFe Cl3. But the flocculating particles were relatively small and easily crushed, which were formed by PAC.Fe Cl3 should be used rather than PAC in the process of coagulation before HDS device. The optimal dosage of flocculants was 21mg/L when the flow was 600 m L/min.④The effect of separation of HDS-semicircular device was lower and less stable,relative to HDS-whole circular device,it is best to keep with HDS-whole circular device.⑤HDS was suitable for separation of insoluble particle effluent,rather than soluble substance such as COD.