Research On The Influence Mechanisms And Processes Of Chemically And Biologically Induced Calcium Carbonate Mineralization

Calcium carbonate mineral is one of the most common and important mineral in sediment environment,which also distributes widely in the Earth.It is also a crucial environmental mineral,and the processes of mineralizaiton were regulated by chemical and biological effects.The relative research work showed that,on the one hand calcium carbonate mineralization is a carrier of the environment change information in different spatial and temporal scale.On the other hand,the mineral which were formed by mineralization processes has the function of environment contamination remediation and treatment.This function had been applied widely in many fields,like underground water pollution control,in situ soil contamination remediation,modification of geotechnical engineering.While,about the chemical mineralization,recently traditional research mainly focused on field acquisition or lab experimental crystallization and mineralization of samples.The research on the processes and effect under different saturation index and different component of porous media had been limited on 2D scale,which can not describe the real state of calcium carbonate mineral in the 3D scale,either in the pore scale.About the biomineralization,for mostly recently traditional research work,the biomineral were extracted from bacteria suspension by centrifugation and deposition,which can not achieve the in situ and non destructive observation of the biomineral in biofilms.It is also lack the research on the interaction between biofilm with calcium carbonate minerals.Therefore,the research on the processes and influence mechanisms of calcium carbonate mineralization has important theoretical value and practical significance.Based on the large number of reference and experimental data analysis,this thesis work achieved the chemical analysis of calcium carbonate chemical mineralization processes and the quantitative analysis of seepage characteristic in porous media by calcium carbonate chemical mineralization experiments,X-ray microtomography,image processing and numerical calculation methods.On the other side,with the help of the in situ,real time and nondestructive visualization technique of microbial induced calcium carbonate mineralizaiton and experiments of biofilms permeability and inactivated response,this research analyzed the influence mechanisms of calcium carbonate biomineralization and products effected onbiofilms.The thesis research work is mainly about:1.Through lab column experiments,mineralization processes of calcium carbonate mineralization solution under different saturation conditions were implemented in a single component porous media.Quantitative analyzed how the parameters effected the chemical mineralization process with chemical analysis,like pH,total alkalinity,calcium ion concentration,sodium ion concentration,flow and differential pressure.At the same time,this research obtained the 3D images of porous media under different calcium carbonate saturation index by introducing X-ray microtomography to scan and 3D reconstruct samples of calcium carbonate mineralization,which thus achieved the nondestructive observation on the processed of calcium carbonate chemical mineralization in porous media.Base on it,for increasing the research accuracy,scanning electron microscope(SEM)was used to analyze the morphology features of the products of calcium carbonate chemical mineralization.2.Through lab column experiments,mineralization processes of calcium carbonate mineralization solution under a single saturation condition were applied in various components porous media.The research utilized the method combined with chemical analysis,numerical calculation and images quantitative treatment to analyze the parameters variation processes of porous medium before and after mineralization reactions,such as substrate surface features,mineralization rate,porosity and permeability,etc,which carried out the research on the influence of porous medium seepage characteristics by calcium carbonate chemical mineralization in pore scale.3.Through a new structure designed flow cell,this research presented an in situ,real time and nondestructive visualization technique which was combined with confocal scanning laser microscopy and Raman spectroscope.Base on this,our research analyzed different situations of calcium carbonate biomineralization and products,like mineral morphology and components,spatial distribution,interaction between mineral and biofilms.4.Through the development of biofilm permeability and inactivation experiments under two actions of calcium carbonate biomineralizaiton and abiotical calcium carbonate fine particle deposition.Combined with the in situ,real time and nondestructive visualization imaging,this research studied the calcium carbonate biomineralization processes influencemechanisms on biofilms base on the analysis on the variation of biofilms structure and morphology after calcium carbonate biomineralization processes and abiotical particle deposition,and also contrasted the diversity between solute transportation patterns and biocide response in biofilms under those two actions upon.The above results showed that,in terms of chemical mineralization,using X-ray microtomography technology,combined with methods of image processing technology,laboratory column experiments,chemical quantitative analysis and numerical calculation,the3 D visualization of calcium carbonate mineralization processes under the conditions of diverse calcium carbonate saturation index and porous medium matrix components could be achieved,meanwhile,it can also realize the quantitative study on mineralization processes influence on the seepage characteristics of porous medium;In biomineralization,based on the unique design of flow cell and the technique combined with confocal laser scanning microscopy and Raman spectroscope,the in situ,real time and nondestructive visualized analysis could be achieved.By the imaging analysis,we found that the formation of biomineral altered the biofilms original characteristics,like inner structure,permeability,etc.So,the biofim can be regulated by calcium carbonate biomineralization.