Biological Clogging in Compacted Mixtures of Ottawa Sand and Kaolinite: Fid-Bau Portal

Biological Clogging in Compacted Mixtures of Ottawa Sand and Kaolinite

Tumuluri, Sailaja / Reddi, Lakshmi N.

Biological clogging of porous media by metabolically active bacteria is an important issue in Geoenvironmental engineering. In this paper, the role of two important factors influencing biological clogging is evaluated. Results are presented from two different series of percolating experiments: (1) experiments conducted with sterile and unsterile soil, (2) experiments conducted with soils subjected to low and high hydraulic head. A. mixture of Ottawa sand and Kaolinite was used as the porous medium and Pseudomonas aeruginosa as the bacterial culture. Results indicated that filtering as well as clogging by bacteria occurred in soil samples, as reflected by the reduction in the CFUs (Colony Forming Units) of the effluent compared to the influent CFUs. Comparisons of pore size distributions (PSD) of the soil before and after clogging revealed that both biomass growth and biogas generation were responsible for the permeability reduction. Experiments conducted with sterile and unsterile soil revealed that higher reduction in permeability could be achieved in unsterile soil because of the presence of indigenous soil microbes. Experiments conducted with sample subjected to high hydraulic head revealed that high heads would result in biofilm rupture formed on the surface, which would result in subsequent increase in permeability.