Microbiological and molecular evaluation of an alluvial water well field and fouling-related phenomena
An important source of water for the city of North Battleford, Saskatchewan is groundwater extracted from wells installed adjacent to the North Saskatchewan River. Unfortunately, these wells undergo fairly rapid deterioration (3-4 years) leading to reduced well capacity and water quality. The reasons for this deterioration are poorly understood. The studies in this thesis have tried to quantify the prevalence, activity and diversity of microbial populations in the aquifer and to explain the possible outcomes of microbial interaction with the environment which might lead to biofouling of the wells. A panel of conventional cultural, microscopic, metabolic and molecular techniques were utilized to analyze water, sediment and biofilm samples collected from various locations in the aquifer. The studies indicated that the aquifer was anoxic and harboured abundant concentrations of iron and manganese very close to the well and also presence of diverse groups of organisms including Fe-, Mn-, S-oxidizing bacteria as well as Fe-, Mn-, nitrite- and sulphate-reducing bacteria. A two year spatio-temporal study indicated that the biofilm growth significantly increased within the 1-2 m zone from the well and were also associated with a rapid reduction in specific capacity of the well. PCR, qPCR, and DGGE analyses indicated that the microbial community composition and diversity varied with space and time with greatest changes detected within the zone proximal to the well. Sequence data indicated that the major bacterial species prevalent in the aquifer belonged to Sulfuricurvum spp., Rhodobacter spp., Methylobacter spp., Acidovorax spp., and Geobacter spp. The studies demonstrated that water extraction influenced microbial community diversity, activity and composition, the effect of which did not extend beyond 1-2 m well radius. The application of impressed current did not demonstrate any anti-fouling effect, but rather favoured the growth of biofilm around the well and the accumulation of insoluble precipitates leading to accelerated deterioration of the well. Overall, the microbial community diversity, activity and composition in the study aquifer changed with respect to time and space, and water extraction. These changes altered the biogeochemical processes in the aquifer, especially within the zone closest to the wells leading to clogging and well deterioration.
Groundwater, Biofilm, Pumping, Biofouling, Clogging, Microbial community, Denaturing Gradient Gel Electrophoresis (DGGE), Principal Components Analysis (PCA), Impressed current.
Doctor of Philosophy (Ph.D.)
Food and Bioproduct Sciences