Transport of bacteria in porous media and its enhancement by surfactants for bioaugmentation: A review

•Theoretical bases associated with bacterial transport are presented•Factors influencing bacterial transport are reviewed•Mechanisms for surfactant to enhance bacterial transport are summarized

The success of bioaugmentation processes for groundwater bioremediation requires efficient transport of bacteria in the subsurface environment. In this paper, the factors that influence transport of bacterial cells in porous media are reviewed and the effects of surfactants on the transport are discussed. Movement of bacterial cells in porous media is a process driven by advection and hydrodynamic dispersion forces of fluids. Immobilization of bacterial cells takes place due to processes such as adsorption and straining. Blocking and ripening along with bacterial migration process decrease and increase the retention of cells in porous media, respectively. Physicochemical properties of the porous media, groundwater chemistry, and properties of the bacterial cells affect the transport behavior. Surfactants have the potential to modify bacterial surface properties for both bacterial cells and medium solids, and thus enhance bacterial transport.