Hydrocyclone Membrane Separator To Deal With Low Concentrations Of Oily Wastewater

Combined the mechanism of rotary flow separation and membrane separation, a new rotary flow membrane separator was designed based on the theory of two-phase flow to apply to the treatment of low concentration oily wastewater. The concentration polarization is avoided by rotation of feed and the sediments on membrane were reduced effectively by cut force from flow rotation.Based on the basic equations of hydrodynamics, the dynamical characters of the fluid in the separator were analyzed. The movement Characters of two-phase fluid in the separator were discussed; the three-dimension velocity, the distributing of the pressure along with the radius and the distributing of the cut force in the axis and radial were given. In the end, the force suffering of the oil drop was simply discussed.The influencing factors of the treatment of oily wastewater with lower concentration through hydrocyclone membrane separator were researched. The results of experiments show that the increase of membrane pressure brings about the improvement of the initial flux, which induces the flux decline sooner, and the optimum membrane pressure in the study is 0.01MPa. Increase of the inlet flux redounds to the improvement of the separation efficiency and the oil retention ratio. Along with the increase of feed concentration, the steady flux declines and rejection ratio of oil raise. After treatment, the oil concentration in permeation fluid is lower than 10mg/L. The membrane fouling and cleaning methods in the process of the treatment of oily wastewater with lower concentration were researched. The results show that the degree of membrane fouling is less; the resistance of membrane is 76.9% account for the total resistance. The methods of backwash, acid wash, alkaline wash and petroleum ether wash were used to clean the fouling membrane after 6h running respectively, and the flux recoveries of membrane are all over 80%. Those results indicate that the hydrocyclone membrane separation could avoid or lighten membrane fouling and concentration polarization, and the membrane is easier to clean after fouling.