Investigating Fate of Silver Nanoparticles in Wastewater Biofilms

As industrial advances make everyday life easier for human kind, the processes by which we need to maintain sanitary conditions for both water and wastewater treatment will become increasingly complex. Innovations in food packaging and textile design incorporate engineered nanoparticles (ENPs) to increase antimicrobial properties of clothing, maintain product color, and keep food in packaging from spoilage. For most products, ENPs released will enter the sanitary sewer system, and ultimately wastewater treatment plants. Biofilms grow universally on surfaces where a protective layer of extracellular polymeric substances (EPS) shields attached cells from stressors. In wastewater treatment, complex biofilms are utilized as a biological process for nutrient removal. Along with manufacturing innovations, the technology to study wastewater processes also continues to advance. Understanding complex biological communities requires detailed expertise in metagenomics for identifying bacteria present in a unit process of interest. This dissertation seeks to address both issues with respect to biofilm processes. First, a review of ENPs and their interaction with wastewater microbial communities lays groundwork for understanding the current state of knowledge. Then, a comparison of multiple methods to identify wastewater biofilms will help to understand the proper application of metagenomics to study changing biofilms in the presence of ENPs. Finally, multiple bench scale reactors and a quartz crystal microbalance are used to quantify ENP accumulation in wastewater biofilm. These studies advance the field of biofilm research by aiding in understanding how new technologies impact the biological treatment processes applied in wastewater treatment, as well as improve on the metagenomic identification of biofilm communities in these environments