A two-dimensional study of biofouling and pathogen transport in the subsurface

Biofouling and pathogen contamination are major concerns in water well operations. A two-dimensional sandbox system was set up for investigating the biofouling process and the transport behaviour of Escherichia coli O157:H7 in a subsurface environment. Imaging of the sandbox using a CCD camera was found to be effective in monitoring the biofilm growth in this system. Biofilm formation occurred mainly near the glucose injection port but was found not to significantly impact the overall hydraulic conductivity of the sandbox. An increase in dispersion, evident as finger-like spreading and channelling of the Lissamine green B tracer, was associated with biomass accumulation in the sandbox. Transport of E.coli O157:H7 was found to be faster than the tracer LGB, although there was significantly increased E.coli detention in the biofouled sand matrix. Microscopic observations of the biofilm and water revealed that E.coli O157:H7 was mostly associated with the biofilm.