There have been many empirical studies of such biofouling over the last few decades, but a good understanding of factors affecting bacterial growth and aquifer clogging is still not available. One reason is that good visualization methods for observing the processes involved were lacking until recently. The visualization approach being proposed here is expected to add significantly to our understanding of the processes of importance. An apparatus for visualizing the growth of bacteria on surfaces that simulate a groundwater aquifer and for measurement of fluid velocities as well has been constructed. The apparatus consists of simulated aquifer pore structure with defined channel widths etched on a silicon wafer.
Growth is visualized by a light microscope with moving stage, with images stored in a computer.
The SPIE is seeded initially with a bacterial culture, and liquid containing nutrients and substrate is pumped through the SPIE with a syringe pump. The resulting growth, its distribution and pressure losses across the SPIE are recorded over time. From the understanding that is obtained, cultures with different adhesion properties will be evaluated under a variety of growth substrates at different concentrations and with different fluid velocities and aquifer system geometries. The effect of disinfectants on the biofilms that develop will also be evaluated. Two case studies have now been conducted using a defined pore structure with a checkerboard layout, and with randomly varying pore widths.