Reducing Soil Permeability Using In Situ Biofilm-Forming Bacteria: Overcoming Testing Apparatus Challenges

Growing biofilm in saturated sand has been shown to reduce the permeability of soil by one or more orders of magnitude and may be a viable approach to reducing seepage in the field; however, obtaining laboratory permeability results in soil samples where biofilm is being developed is difficult. Adding nutrients results in the formation of biofilm in the soil but also the formation of biofilm in the piping and other areas of the permeability testing apparatus. In addition, some bacteria produce gas as a product of metabolism and this gas can collect in the apparatus and interfere with fluid flow. This paper presents an approach to permeability testing that effectively minimized the growth of biofilm and the collection of gas in the testing apparatus for multiple sand samples treated with a nutrient solution over a period of more than 60 days.