The widespread occurrence and environmental impacts of microconstituents has received increasing attention in recent years. An important class of microconstituents is pharmaceutically active compounds. There is a growing body of evidence that suggests chronic exposure to pharmaceutically active compounds, even at extremely low concentrations could have adverse effects on ecosystems, such as impaired embryo development, modified feeding and social behavior of fish, suppression of growth and reduction in respiration in algae. While some of these effects are reversible, other anatomical, physiological, and genetic alterations are permanent. Thus, the challenge of assessing, understanding, and mitigating the deleterious influence of pharmaceutically active compounds, and microconstituents more broadly, on the environment is one of the great challenges facing the environmental engineering and science community. Current approaches to study pharmaceutically active compounds fate in biological wastewater treatment generally lack a mechanistic basis and therefore cannot unambiguously pinpoint the protagonist microbial communities and metabolic pathways that are active in the removal of pharmaceutically active compounds. This leads to a lack of consensus regarding the identity of active species and critical attenuation processes. To unravel the conundrum of complexity and site specific results, the PIs propose a fundamental approach to understanding the fate of pharmaceutically active compounds - one that can guide future research and implementation efforts. This project aims to develop a clear understanding of the microbial "active fraction" in activated sludge which is responsible for the transformation and removal of pharmaceutically active compounds, and to elucidate the constituent metabolic pathways. A secondary objective is to quantify and differentiate between growth associated (linked to anabolism) and non-growth associated (linked to catabolism or fortuitous reactions) pharmaceutically active compounds transformation and degradation. Understanding the interplay of microbial processes acting on contaminants of emerging concern is critical to meeting the scientific challenges now facing water quality researchers and professionals. The approach to understanding these processes offered in the proposed research may seed future scientific investigations aimed at understanding biodegradation mechanisms throughout the environment.
The influence of anthropogenic chemical mixtures present within the environment at low concentration is one of the great challenges facing scientists and engineers in the 21st century. Effective wastewater treatment is critical to maintaining water quality, but what is traditionally thought of as effective may need to also include microconstituents - compounds that these facilities were never specifically designed to treat. This study will further the development and application of advanced microbial-ecological techniques to shed new light on how bacteria within activated sludge interact with pharmaceutically active compounds. The advanced understanding enabled by these state-of-the-art molecular tools can be extended to interrogate pharmaceutically active compound metabolism in different activated sludge configurations. Further, the knowledge of the "active fraction" and metabolic pathways can help improve standardized protocols that can be used by future studies to estimate the extant biokinetic parameters and to construct more accurate predictive models for pharmaceutically active compounds removal. From a fundamental perspective, there is no metabolic model to date, that can describe pharmaceutically active compounds degradation pathways. This is possibly due to a lack of detailed studies related to understanding the mechanisms by which pharmaceutically active compounds are biodegraded within mixed communities of bacteria. As part of this project, the PIs propose to develop and parameterize such a model.
