## 5 Conclusions  
In this study, we conducted a comprehensive analysis of groundwater pollutant transport models, integrating the innovative application of bacterial chemotaxis to enhance the efficacy of groundwater remediation strategies. Groundwater contamination poses a significant and widespread environmental challenge, where conventional treatment methods have demonstrated limitations. Our findings underscore the significance of tailoring remediation approaches to the specific characteristics of each site, emphasizing the necessity for a multifaceted and interdisciplinary strategy. The numerical results indicate that chemotactic bacteria, which can rapidly adapt as the pollutant concentration decreases, have seen a 112% increase in concentration in the low-permeability area. The integration of genetic engineering offers a promising avenue for optimizing bacterial performance, potentially augmenting their chemotactic capabilities and resilience in diverse environmental conditions.  
Moreover, we propose that a holistic approach, in the context of this research, involves not only the genetic enhancement of bacteria but also the synergistic application of chemotactic principles alongside other treatment modalities. The numerical results suggest that the use of some traditional remediation methods, such as surfactants, can increase the extent of impact on low-permeability areas, which will be beneficial to bioremediation.  
With the increasing amount of research currently being conducted, chemotactic bacterial remediation is hopeful to stand out as a key component of environmental restoration efforts in the future. Especially for monocyclic or dicyclic aromatic hydrocarbons, due to their higher solubility in water, such pollutants buried in low-permeability areas can continuously dissolve in groundwater, posing a significant threat to human health. However, bacteria have a considerable decomposition efficiency for these types of pollutants. This method holds the promise of significantly mitigating the impact of contamination, leading to the restoration of cleaner and safer groundwater resources. The envisioned outcome is a sustainable and enduring solution for environmental recovery, one that integrates scientific innovation with ecological stewardship. This study only considered the chemotaxis of chemotactic bacteria, which is only one of the important indicators of chemotactic bacterial remediation, and in real life, it will involve many other aspects such as bacterial colonization and the decomposition of pollutants. Therefore, more research is needed in this area in the future.  
For the research article, the following contributions have been made by the authors: Conceptualization, S.C. and H.Z.; Methodology, S.C.; Software, X.W.; Validation, H.Z., X.W. and X.Z.; Formal analysis, S.C.; Investigation, X.Z.; Resources, H.Z.; Data curation, X.W.; Writing--original draft preparation, S.C.; Writing--review and editing, X.Z.; Visualization, X.W.; Supervision, T.L.; Project administration, H.Z. and T.L.; Funding acquisition, H.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Shandong Provincial Natural Science Foundation [grant number ZR2021 ME108, ZX20220090, ZR2021 JQ18], the Program of Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment: Integration of Ecological and Environmental Protection in Yangtze River Delta [grant number ZX2022 QT047], and the Open Foundation of State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control [grant number SEMPC2023002].