The U.S. wastewater industry is struggling to solve the critical problem of protecting sensitive receiving waters from microconstituent chemicals, including pharmaceuticals, hormones and industrial chemicals. These compounds are receiving increasing attention due to their frequent detection and their disruption of ecosystems at very low concentrations. Advanced physical-chemical treatment processes, such as reverse osmosis, can be effective at removing many of these chemicals, but their energy consumption and environmental consequences have been criticized, and they can be cost-prohibitive to many communities. Biodegradation of these contaminants is therefore attractive, but there are critical knowledge gaps in how such systems can be designed for high levels of performance. Biofilm-based systems are seeing increasing use in wastewater treatment systems, largely for nitrogen removal, where attached microbial communities are grown on plastic surfaces that are submerged in wastewater. This project will evaluate the hypothesis that biofilm properties, such as microbial populations, absorbance characteristics, and biodegradation rates of microconstituents with specific chemical properties can be "engineered" by targeted design of attachment media chemical and physical characteristics. Preliminary results suggest such properties can be used to produce biofilms with enriched communities of ammonia-oxidizing bacteria (nitrifiers), and also to increase rates of hormone removal. This project will include evaluation of microbial attachment of specific bacteria of interest (e.g., ammonia and nitrite oxidizers) to chemically well-defined surfaces (self-assembled monolayers), modeling of these interactions, and evaluation of mixed cultures on these surfaces. These results will be used to develop reactor systems in which the additional parameters of surface roughness and shear are evaluated, with surface chemistry, to determine effects on functional behaviors, including removal of target microconstituents and cometabolic activity.
This project will address the critical need for sustainable microconstituent removal from wastewater, while providing cost and energy savings. The project will provide new, fundamental insights to how surfaces can be designed to influence biofilm development, populations, and functional performance, which should produce important new design strategies for process engineers that utilize biofilm-based systems. These results should be of great use to communities seeking cost-effective technologies to reduce discharges of pharmaceuticals, hormones, and industrial chemicals to sensitive receiving waters.
