Prof. D. N. Singh

SHASHANK B. S

Indian Institute of Technology Bombay, Powai, India BS_SHASHANK@YAHOO.CO.IN

INVESTIGATIONS ON BIOGEOCHEMICAL INTERACTIONS IN SANDS

Conventional geotechnical engineering theories and practices consider physical, chemical and mineralogical aspects of geomaterials (naturally occurring and/or anthropogenic), and do not account for the effect of biogeochemical processes impinging on them. Courtesy earlier studies, it is well-known that these processes also cause alteration in the state and composition of geomaterials. One of such processes is?Biogenic Calcite Precipitation?(BCP), which has attracted the attention of several researchers, worldwide, in the recent past. However, not many efforts have been made to investigate biogeochemical interactions, which primarily control the BCP in laboratory investigations that involve a sand column, bacterial suspension and cementing solution. With this in view, efforts have been made to investigate the (i) kinetics of urea hydrolysis (UH) in the presence of urease enzyme from microbes cultivated in laboratory (i.e., Sporosarcina pasteurii) and extracted from plants (i.e., Jack bean meal), and (ii) influence of urea concentration, buffer capacity, and cell harvesting method on UH. Furthermore, an attempt has been made to investigate the mechanisms associated with the interaction of bacterial suspension (read cells) with substrates (viz., sand grains and biogenic calcite), which is a precursor for the BCP. This fundamental study, which has been conducted by employing?Atomic Force Microscopy?and?Extended Derjaguin-Landau-Vervey-Overbeek?theory, provides an insight into the biosorption on sand grains and the biogenic calcite.