Biofilm with highly heterogeneous interior structure for pollutant removal : Cell distribution and manipulated mass transport

Biofilm wastewater treatment had been applied in practice. Conventionally the biofilm was modeled as a uniform structure to simplify the analysis. This study for the first time established a three-dimensional biofilm model with distributions separating living cells, Extracellular polymeric substances (EPS) and pores, based on which the local fluid flow velocity and pollutant diffusion and reaction fluxes inside the biofilm were numerically evaluated. Both the uniform structured and previously proposed heterogeneous models had been confirmed to overestimate the performances of a biofilm for wastewater treatment. The survival strategies of living cells in biofilm were discussed. Besides exposing to fresh pollutants for maximizing pollutant uptake, the tendency to form small aggregates of cells for shortening diffusion length so furnishing the pollutant with reduced diffusional resistance to living cells was also for the first time noted. This communication advanced the knowledge to comprehend the detailed processes in biofilm.