A study on biological clogging of nonwoven geotextiles under leachate flow

This paper presents results of long-term permittivity tests using leachate to evaluate biological clogging of nonwoven geotextiles. Three types of geotextiles with varying masses per unit area were used in the tests. The identification and quantification of microorganisms in the geotextile were carried out as well as microscopic investigations. The accuracies of semi-empirical models to evaluate the kinetics of bacteria growth and to correlate hydraulic properties and microbiological parameters were examined. Permittivity tests under increasing water heads were also performed on the geotextile samples already subjected to long-term leachate flow in order to evaluate the values of water heads required to wash the biofilms out of the geotextile pores. The results of the tests showed the marked reduction of geotextile permeability due to biological clogging and that the results of the predictions by semi-empirical methods were consistent with the biological mechanisms observed.