Permeability distribution for filter media characterization in solid liquid filtration

• The filter media resistance is not a constant value but is distributed.
• The separation of variables time and area improves data evaluation.
• Permeability distribution allows a good comparison between different filter media.

In solid liquid filtration, textiles represent a key element of the setup where it represents the barrier between disperse solid particles and the filtrate. Among other characteristic textile data, the specific flow at standard test conditions is relevant information of filter performance. Nevertheless filter media with comparable characteristic data may exhibit quite different filter performance in terms of filtration rate and filtrate clarity. For a better description of the interaction between filter media and suspension the determination of the permeability distribution (PD) is proposed. This characteristic function is derived from filtration tests where the filtrate is obtained cumulatively over time at constant pressure. Experimental data show that for the same suspension different filter media with different mean permeability show different permeability distributions but also result in different specific cake resistance.

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