Microbially Induced Carbonate Precipitation (MICP) is a technology to produce carbonate through urea hydrolysis using urease-producing bacteria. In heavy metals-contaminated soil, MICP can be used to stabilize soil heavy metals in soluble form to insoluble form like MeCO3, but the inhibitory effect of heavy metals on urea hydrolysis can affect the stabilization. In this study, the stabilization effect of MICP on soil Cu was assessed in focus on the inhibition of Cu on urea hydrolysis in four different soils. MICP was applied by injecting solution containing OD 1.0 Sporosarcina pasteurii, 4 g/L TSB, and 450 mM urea into the soils spiked with 1000 mg/kg of Cu, and synthetic precipitate leaching procedure (SPLP) was used to quantify the stabilizing effect of MICP. The Cu concentrations leached by SPLP test reduced after MICP application in all soils, but the stabilization effect varied from 6.4% (i.e., 28.5±1.0 to 26.7±0.5 mg/L) to 84.2% (i.e., 22.7±0.6 to 3.6±0.2 mg/L). The amount of Cu stabilized was determined by urea hydrolysis, which was approximately 37% of the amount of urea hydrolyzed. The inhibitory effect of soil Cu on urea hydrolysis was assessed in five different Cu spiking concentrations (i.e., 0, 100, 250, 500, and 1000 mg/kg). In all soils, the urea hydrolysis decreased as the spiking concentration of Cu increased. However, the inhibition was determined by the Cu concentration in soil solution than total concentration in soil. The sigmoidal curve for the inhibition rate of urea hydrolysis to Cu concentration in soil solution was derived from four different Cu spiked soils, and IC50 was determined to be 6.5 mg/L as Cu concentration in soil solution.

Inhibition of microbially induced carbonate precipitation by soil solution Cu and its effect on the stabilization of soil Cu

2019 Fall National Meeting

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