9753086 Figueroa The active population distribution of nitrifying bacteria is difficult to study using traditional cultivation techniques such as most probable number and selective plating. This is partially because nitrifying bacteria grow very slowly - replicating once every eight hours under optimal conditions compared to E. coli which replicates once every twenty minutes. Culturing techniques also require the disruption of the biofilm structure and a loss of spatial distribution information. One relatively new microbiological technique that can be applied to an intact biofilm sample is Fluorescent In-Situ Hybridization (FISH). The application of FISH to full-scale wastewater treatment systems is limited. This could yield important information that can be correlated with performance and then used to quantify the active population for process modeling and optimization. Other techniques such as confocal microscopy and microprobes may be applicable to intact biofilm samples collected from full-scale trickling filters and may provide additional information for process control. The main research objective is to investigate the application of relatively new microbiological and biofilm techniques to characterize intact biofilm samples and determine whether this information can be used to improve process modeling and optimization. Secondary objectives are to develop new skills and collaborative relationships to increase competitiveness for the use of these novel techniques to quantify phenotypes and their distribution in full-scale biofilm processes. ***
