膜过滤过程中滤饼层阻力及通量变化计算研究

Calculation of Cake Layer Resistance and Flux Change in Membrane Filtration

膜过滤时间延长,阻力增加,通量减小。滤饼层是阻力主要来源之一,通过计算滤饼层阻力和通量变化,来研究滤饼层阻力和通量变化的关系。可以得出:投加絮凝剂或相应物质,因为絮凝剂等物质不对膜产生强力吸附,且比表面积大,吸附污染物后被剪切力或摩擦力冲下,减少滤饼阻力较为容易,膜通量恢复及时,长时间保持高通量。在数值计算时,纯膜过滤也难以界定滤饼形成的瞬间时刻,但投加絮凝剂后可以根据通量变化来确定滤饼形成和脱落时刻,最后根据模型分析减少滤饼层阻力的方法。

With the increase of filtration time, the resistance increases and the flux decreased. The cake layer is one of the main sources of resistance. Through the calculation of filter cake resistance and flux changes, this paper studied the relationship between filter cake resistance and flux. It is necessary to add the flocculant or equivalent material, because materials such as floc- culant do not have strong adsorption and their membrane and specific surface area is big. After the adsorption of pollutants by shear force down or friction, it＇s easy to reduce the filter cake resistance. Membrane flux can be recovered in a timely manner to keep high flux for a long time. In the numerical calculation, it is difficult to define the moment of filter cake formation by pure membrane filtration, but the time of filter cake formation and shedding can be determined by the flux change after flocculation. Fi- nally, according to the model, approach was proposed to reduce the cake resistance.