天然海水环境下离子浓度对MICP反应的影响OA北大核心CSTPCD

Microbial geotechnical technology improves the mechanical properties of basic materials through the process of biological mineralization,making it more suitable for building or solving environmental problems in multi-disciplinary fields.Calcium carbonate produced by microbial mineralization is the main component that improves the mechanical properties of basic materials,but the production efficiency and form are affected by many factors.By means of ion meter,pH meter,SEM,EDS and XRD,the influences of the concentration and proportion of calcium chloride and urea and the volume ratio of bacteria liquid and cementation liquid(calcium chloride,urea)on the morphology and crystal composition of precipitates in natural seawater and deionized water environment during the mineralization process were investigated.The results showed that:production of calcium carbonate is poorer when calcium ion concentration and the ratio of Ca2+to urea are lower,however,the ion has an inhibitory effect on the production of urease by bacteria when the initial calcium ion and urea concentration exceeds 1.0 mol/L.The more obvious inhibition effect was observed at a higher ion concentration,and thus a lower precipitation product rate.The amount of precipitates and precipitation rate in the seawater environment were higher than those in the deionized waterenvironment.When the volume ratio of bacterial to cementation solutions are 1∶4 in deionized water and less than 1∶10 in seawater,the amount of calcium carbonate is higher.The crystal type in deionized water is mainly calcite,while the crystal type in seawater is mainly of magnesium salt type.