ENZYMATIC BIOCATALYSIS OF ENDOCRINE DISRUPTING CHEMICALS IN WASTEWATER: A SUSTAINABLE TECHNOLOGY FOR EMERGING CONTAMINANTS

 

Project Summary

As beneficial water reuse becomes a common practice throughout the world, concern over the effects of residual contaminants on aquatic ecosystems and human health is escalating. Found in everyday commercial items like plasticizers, pharmaceuticals, pesticides, and flame retardants, endocrine disrupting chemicals (EDCs) have been shown to disrupt hormone function in exposed organisms, causing adverse physiological effects even at very low concentrations. Typically, these contaminants are not completely removed during conventional wastewater treatment, and are discharged into receiving waters where they can potentially harm ecosystems and re-enter potable water supplies. Although some physical and chemical treatment methods exist for treating EDCs in wastewater, they are expensive and unattainable for the majority of the world. An inexpensive, sustainable treatment method is sorely needed for removing these emerging contaminants from wastewater.

 

Intellectual Merit

The overall objective of our work is to critically evaluate the technical and economic feasibility of enhancing EDC removal in wastewater treatment plants (WWTPs) using a symbiotic consortium of fungi and bacteria with a demonstrated ability to catalyze the elimination of EDCs. Although fungi have demonstrated such a capacity to degrade EDCs in batch systems containing nutrient-rich growth media, the use of mycelia in continuous-flow systems for the treatment EDCs in wastewater has not been reported. The PI has recently shown, however, that certain fungi are able to grow in wastewater and produce biocatalytic enzymes that are capable of catalyzing the destruction of EDCs. Similarly, others have recently shown that ammonia oxidizing bacteria (AOB) can co-metabolically degrade certain classes of contaminants in wastewater using monoxygenase enzymes, and that in certain scenarios, bacteria-fungi interactions can result in a synergistic enhancement of overall degradative capacity. Therefore, to realize the full potential of WWTP ecology, we intend to combine analytical chemistry and molecular microbiology techniques to understand the extent to which the AOB and fungal communities can be enhanced and augmented, and the mechanisms by which synergism can be promoted between inoculated and/or native fungi and AOB in WWTPs. It is envisioned that by promoting unique, enzyme-driven biocatalytic pathways, wastewater treatment processes can be optimized for effective EDC treatment while maximizing cost effectiveness. To meet this objective, data generated from a series of batch and bioreactor experiments will be incorporated into a Life Cycle Assessment (LCA) of the technology to determine its relative sustainability compared to more conventional physical and chemical treatment methods. Combining the results of our lab-scale research with the LCA results will enable a guided deployment of the technology for the treatment of EDCs at a pilot-scale ecological wastewater treatment system (a.k.a., eco-machine). If validated at the pilot-scale, then other eco-machine systems could be similarly converted, and conventional wastewater treatment plants could be enhanced or upgraded to include EDC-treatment.

 

Broader Impacts

In addition to supporting graduate and undergraduate student research, the proposed activity will disseminate information to the local community through an interactive website on safe water practices and guided tours of an eco-machine facility. The technology developed in this work would be the first to investigate the concept of enzyme-mediated destruction of emerging contaminants in wastewater using immobilized whole mycelia in combination with AOB, which could represent a significant cost savings over traditional treatment methods. Additionally, it is expected that improvements in the analytical identification and quantification of EDCs and their metabolites will be developed during this work, enabling progress in the understanding of EDC-degradation pathways, and thereby increasing our ability to optimize treatment processes for their removal. Finally, the LCA-driven development of the proposed technology will provide a detailed accounting of environmental costs and benefits and provide a framework for critical evaluation of the economic feasibility and long-term viability of the process, while providing insight into how its design can be improved for greater sustainability. This systems-based approach represents a new paradigm for holistic wastewater treatment, which could serve as a model for the future development of sustainable infrastructure.