Transport Mechanisms And Mathematical Model Of E.coli In Soil

Microbial migration in the soil is closely connected to agriculture,industry,environmental protection,water conservation and other areas.It has great significance to master the transport of microorganisms in the soil,establish appropriate models to predict the process for the establishment of biological control measures and the development of in-situ bioremediation technology.The paper selected two different soil particle size?27?m,347?m?and chosen Escherichia coli as a research object,established a linear relationship between the concentration of E.coli and the absorbance OD₆₀₀;First by laboratory soil column experiments studied the process of migration of microorganisms in the soil;Then improved colloid filtration theory based on the existing mathematical model;Finally,established a relatively accurate CFT model which has strong applicability.A According to the experimental data analysis,there has a good linear relationship between the concentration of E.coli and the absorbance OD₆₀₀,which correlation coefficient R² = 0.9965,in this case,the corresponding concentration of E.coli can accurately and quickly obtained by the determination of OD₆₀₀ value.The linear relationship C=0.86073×OD₆₀₀.In this article,it was established a relatively accurate as well as applicability strong mathematical model,which improved to CFT based on the existing quality model,according to the quality of the model,taking into account the ease of understanding and description,given an improved model CFT analytical solution under certain conditions.Solving the correlation coefficient v and k_att+k_str,a correlation coefficient of 0.889,can be accurate description of the E.coli transport law in the soil,and to solve the correlation coefficient.The correlation coefficient v and k_att+k_str substituted into consideration hydrodynamic dispersion conditions improved CFT model,solving the water power diffusion coefficient D.Through different concentrations of bacteria suspension transport in soil column experiments,the results showed that with the decrease of the concentration of the bacterial suspension,effluent stabilization time will be extended,and reaches steady effluent concentration will also decrease.E.coli effluent quality accumulation rate also reduced with the decreases of bacterial suspension concentration.Through the research of soil column experiments at different durations,analysis the relationship between the effluent E.coli total mass and the retention of the total E.coli mass in soil.The effluent E.coli total mass impact from the power process,the retention of the total E.coli mass in soil mainly affects the resistance process,that the two processes influence transport of E.coli depends on the experimental time.When the experiment time is short,theresistance of E.coli transport process will play a significant role in the retention rate of E.coli can reach 86.87%;when a long pass into the bacterial suspension time,dynamic process of transport for E.coli obvious,E.retention rate was 27.74%.E.coli transport assay in different soil particle size showed that surface-cake in E.coli retention process has played a crucial role,and the smaller the particle size,the more prone the soil into account the phenomenon of surface-cake.surface-cake occurs in the surface of the soil,hindering the inward transport of microorganisms in the soil column,and so continued to gather microorganisms in the soil surface layer formed surface-cake.When the surface-cake is not formed,the microorganisms retained mainly by straining and adsorption;when the surface-cake is formed,surface-cake will greatly be a prominent role,becoming the main cause of microorganisms retention,transport mechanism of microorganisms will change.This is the retention mechanism of microorganisms transport in soil.