Towards successful bioaugmentation with entrapped cells as a soil remediation technology: Effects of the water content and cell dispersal.

Soil remediation technologies are proposed that rely on inoculation with degrading microorganisms entrapped in protective carriers. A mathematical model developed to model entrapped cell bioaugmentation describes the 3-D diffusion-driven mass transfer of benzoate, and its mineralization by Pseudomonas putida KT2440 entrapped in alginate beads spatially distributed in a sandy matrix. The model is validated against experimental data where one, three, and nine degradation hotspots are spatially distributed in sandy microcosms. The lowest mineralization rates are observed in dry conditions (water saturation 7%) and agree satisfactory well with model predictions. In contrast, much larger mineralization rates are measured for wet conditions (water saturation of 68%). This discrepancy originates from extensive cell dispersal, not accounted for in the model, which occurs in wet conditions but is restricted in dry conditions, as confirmed by performing cell counts. This highlights the potential of entrapped cells when they act as seeds for soil colonization.