Laboratory-scale treatment and microbial profiling of biofilms grown in water supply wells.

A biofilm is a unique community of bacteria and their excreted substrates that are attached to a surface. In most cases, the build up of this biofilm is undesirable and has adverse affects on its surrounding environment causing what is termed biofouling. Biofouling includes both biological and precipitant build-up. Unfortunately, biofouling is a very common problem affecting everything from medical implants to dental water lines to water-producing wells, which is the case for this study. Aquifers and the wells that draw from them represent one of the main sources of water supply in the South Texas region. Three wells currently diagnosed as being severely biofouled were studied in this project. The wells are located on Staggs Ranch in southern Bexar County, Texas, and are producing water from the Carrizo aquifer. Several methods, including three chemical biocides and UV radiation, were employed to ascertain which treatment was the most successful for irradicating the bacterial community of the biofilm. This was accomplished by analyzing water chemistry and quality parameters as well as conducting ex situ treatment testing and bacterial identification. It was determined that a 1% hydrogen peroxide treatment was the most effective to lower colony forming units (CFU) below countable levels, with sixty-nine isolates comprising the biofilm community.