EXPERIMENTAL RESEARCH OF MICROBIAL-INDUCED CLOGGING IN SANDS

Many problems of latent danger and environmental impact of infrastructure are due to leakage.The latest research of microbially-induced clogging shows that，suitable survival conditions for microorganisms lead to an effective microbial clogging in a relative short time，to reach the aim of decreasing hydraulic conductivity in soils. In this study，tests of microbial-induced clogging were performed in 2 sand columns，where potato soup and glucose were added，and water was added to another column only for a control. The hydraulic conductivity of the sand column supplied with potato soup decreased to 1 /50 of its initial discharge in 3 weeks，and clogging occurred near the leak. The hydraulic conductivity of the sand column supplied with glucose did not change a lot. Then，potato soup was added to the sand column initially served with glucose，and clogging happened near its leak. Clogging stability was tested by increasing water head. The water gradient in the test system was increased from 0. 267 to 1. 067，and the clogging reached a failure gradually. Tests showed microbial-induced clogging in sands was a combination of leakage detection and leakage sealing，which was stable in the case of increasing the water head of the inlet.