Comparison of fine particle clogging in soil and geotextile filters

This paper addresses the differences in the extent of clogging associated with fine particle transport in soils and geotextiles. A common experimental set-up was designed for soil and geotextile filtration. Tests were conducted using a nonwoven, needle-punched geotextile filter sample permeated with fine particle suspensions under constant flow rate. The results were compared with those from similar experiments using soil filters. Geotextile clogging was modeled using an extension of a soil-clogging model. The experimental results assisted in the evaluation of the critical velocity of particle deposition in geotextiles. Comparisons were made between the soil and geotextile clogging models for a better understanding of the clogging mechanisms. It is estimated that the critical velocity for geotextiles is on the order of 10-3 cm/sec, considerably less than the corresponding value for filter soils (10-1 cm/sec). Comparison between soil and geotextile filters shows the geotextile provides a better filtration function without excessive clogging for the same types and sizes of particle concentrations. The modeling simulation showed that both particle numbers and sizes should be considered instead of mass-based concentrations alone in order to estimate the extent of physical clogging.