Experimental study on influence of microbial mineralization on permeability of clay
In order to explore the influence of mineralization on clay permeability,clay was treated by induction of mineralization through Sporosarcina kp-22.The carbonate formation rate of clay after treatment was measured and the clay permeability characteristics were studied.The permeability coefficient variation with the OD600 of bacteria,the concentration of cementation solution and cadmium content were investigated.The influence rule and mechanism of each factor on permeability coefficient were discussed.The empirical formulas to calculate permeability coefficient of clay after mineralization considering the OD600 and concentration of cementation solution were established.The results show that carbonate crystal was formed in the mineralized soil samples,which can fill some pores in the soil,and the permeability coefficient of clay can be reduced by at most one order of magnitude.With the increase of OD600,the carbonate formation rate in mineralized soil first increased and then gradually stabilized,but the permeability coefficient first decreased and then tended to be stable.When the OD600 was greater than 0.9,the carbonate formation rate and the permeability coefficient changed little.With the increasing concentration of cementation solution,the formation rate of carbonate first increased and then decreased.On the contrary,the permeability coefficient first decreased and then increased.When the concentration of cementation solution was 0.8 mol/L,the permeability coefficient was the lowest.With the increasing cadmium content in soil,the mineralization reaction was inhibited and the permeability coefficient increased gradually.Permeability coefficient after mineralization is negatively correlated with carbonate formation rate,which satisfies a linear relationship.The calculated coefficients of the empirical formulas established for permeability coefficient of clay after mineralization agree well with the experimental results.
microbial mineralizationclaypermeabilityOD600 of bacteria solutionconcentration of cementation solution
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