Change in microstructure of clogged soil in soil wastewater treatment under prolonged submergence

Abstract

Laboratory experiments were carried out to observe the changes in the micro-structure of soils during the process of sealing of soil pores under prolonged submergence. When soils were submerged, the infiltration rate which was plotted against time and decreased in assuming a S-shaped curve become eventually stabilized at a constant value. During this process soils were stained with the fluorescent brightener calcofluor white M2R, and then thin sections of soil samples were prepared from clogged soils in experimental columns. The site of clogging was distinctly detected by fluorescence microscopy. It was observed that the soil pores were clogged by entrapment of suspended particles, clay, microbial cells, and their metabolized products (polysaccharides). Mechanisms controlling physical and biological clogging are discussed.

Key Words:

• infiltration rate
• physical and biological clogging
• soil micro-structure
• soil wastewater treatment