###### Abstract
Microbial-induced carbonate precipitation (MICP) technology has become a popular research topic because of its unique environmental friendliness [5; 6; 7; 8; 9]. MICP technology can improve the soil properties, mainly including the soil strength, durability, permeability, pollutant treatment, and crack plugging [10; 11; 12; 13; 14]. Most microorganisms are directly extracted from the natural soil environment, and the use of their own reactions to improve soil properties has little impact on the environment. These advantages are incomparable to those of traditional chemical materials. Therefore, using MICP technology to form an environmentally friendly horizontal seepage-reducing body (HSRB) without damaging the soil structure of the deep aquifer, and analyzing the migration mechanism of microorganisms in groundwater, has great scientific research and practical application value. Three types of microorganisms are used in MICP technology: photosynthetic microorganisms, sulfate-reducing bacteria, and microorganisms related to the nitrogen cycle [15; 16; 17]. The MICP technology based on urea hydrolysis is the most commonly used method for producing calcium carbonate crystals [18; 19; 20]. _Sporosarcina pasteurii_ is a typical urease-producing bacterium [16; 21; 22]. The solution injected into the confined aquifer by MICP grouting technology includes a bacterial solution (_S. pasteurii_) and cementation solution (urea and CaCl\({}_{2}\) solution). For two completely different solutions, the cementation solution was considered as a common solute without biological activity in this study. The migration process of bacteria in groundwater is similar to that of general solutes. In addition to the basic convective diffusion process, bacteria are also affected by filtration, adsorption, desorption, growth, decay, precipitation, and chemotaxis [23]. The establishment of a bacterial migration model requires a certain degree of simplification, and it mainly includes three processes of convection, arrest, and biology [23; 24; 25]. When there is solute migration in groundwater, the solute will undergo physical, chemical, and biological interactions and continue to change. The migration process is complicated. The soil will adsorb the solute, thus blocking solute migration. The migration model can be divided into an equilibrium model and non-equilibrium model (dynamic adsorption model) according to different assumptions [23]. In the past, most studies have adopted the equilibrium adsorption hypothesis--that is, the adsorption of the solute by soil particles is assumed to be instantaneous [23; 26]. However, in many cases, the adsorption of a solute by soil particles is a slow process, and the adsorption often shows nonlinear characteristics [27]. The bacterial migration model considers filtration, adsorption, desorption, death, and other processes, and can fully and accurately describe the migration process of microorganisms in porous media [28; 29]. However, many parameters have been introduced into the bacterial migration model, which has increased the difficulty of calculation and reduced the practicability of the model. Therefore, bacterial adsorption can be regarded as equilibrium adsorption or isothermal adsorption. At present, the batch experiment method is used to measure the isothermal adsorption curve to characterize the solute adsorption capacity of soil. Batch experiments are simple in design, offer good control over experimental conditions, and allow for tests to be conducted in multiple replicates. They are therefore very popular to assess the characteristics of bacteria, and are recommended by some guidance documents [30]. Compared with column tests, simple batch experiments are expected to be more reproducible than column studies, although without considering the complex conditions in accurately predicting processes in the field environments [31; 32; 33; 34; 35]. Results from batch studies can be appropriately employed in the implementation of MICP technology.