Dissolution And Recrystallization Of Iron Oxide During Micp

An MICP field trial was performed at the Integrated Field-Scale Subsurface Research Challenge (IFRC) site, at Rifle, Colorado, USA. Non-destructive geophysical tests were used to monitor changes in soil properties as a function of time, while groundwater was sampled and tested for chemical indicators, including pH and dissolved iron content. During the field trial, the measured concentration of dissolved iron (Fe2+ ferrous iron) increased, which implied that the increased microbial activity resulted in dissolution of naturally occurring iron oxides, which are naturally occurring cementation agents. Column tests were performed to compare dissolved iron concentrations in the effluent of MICP tests performed in silty sands to sands with iron oxide. Release of ferrous iron was observed in the columns with iron oxide mineral phases; however, no observable differences were detected in the distribution of mass of calcite precipitated within the soil columns.