Kelly Burke - US grants

Plastic contamination in the environment is a pervasive global problem with no obvious solutions. Environmental plastics are predominantly comprised of tiny pieces less than five millimeters in length. These so-called ?microplastics? (or ?MPs?) are now found in nearly every environment on Earth, including inside humans and animals, and their future health impacts and ecological consequences are unknown. This research project aims to create safe, efficient, and cost-effective technology to separate and eliminate MPs from wastewater. Outflows from wastewater treatment plants (WWTPs) are a major source of environmental MPs. Taking inspiration from nature, this project will employ freshwater mussels grown by the thousands in tanks to quickly and efficiently filter large volumes of wastewater. When drawing in wastewater for feeding, the mussels will combine the MPs in the wastewater with special bacteria capable of breaking down and destroying the plastic, transforming MPs back into small, naturally-occurring organic molecules. The bacteria and the MP breakdown products will be tested so that nothing harmful is released into the environment. Throughout the project, the team will engage with WWTP operators and state regulators to make sure the technology being developed is practical to implement. In parallel with lab- and pilot-scale technology development, a mathematical model representing a full-scale WWTP system including technical, economic, and social components will be developed. The model will be used for benchmarking and scenario exploration to give decision-makers clear, quantitative answers to the questions: how can our existing WWTP be modified, considering both traditional and novel technologies? what pollution prevention benefits would be achieved and at what cost? The project's focus on existing WWTP infrastructure will allow scientists and engineers to make a large impact with a relatively small investment. Led by a team of 10 scientists and engineers from two universities, the project will also train dozens of graduate and undergraduate students in sustainable biotechnology and will proactively engage students from underrepresented and disadvantaged communities. Multiple outreach and education activities will engage the support and imagination of thousands of K-12 students, teachers, and members of the public.

The objective of this project is to separate and eliminate microplastics (MPs) from wastewater treatment plant (WWTP) effluent. WWTP effluent is the source for approximately half of the MPs now in the environment, and WWTPs can be modified to economically prevent MP pollution of receiving waters. The approach of this project is to employ suspension-feeding aquatic bivalves to efficiently separate and concentrate MPs from water. Further, by co-concentrating MPs with certain MP-degrading bacteria, MP bioavailability will be enhanced. Microbially-mediated depolymerization will be achieved by leveraging the team?s existing collection of 1000 microbial cultures isolated from MPs in aquatic environments, some of which have already been shown to degrade certain plastics. This collection will be augmented by additional strains collected from the WWTP at the University of Connecticut, which will serve as a living laboratory for the project. The scope of the project will encompass both particulate and fibrous forms of polyhydroxybutyrate (PHB), a more readily-degraded polyester, as well as polyethylene (PE) and polyethylene terephthalate (PET), which are more recalcitrant; all are common environmental MPs. To achieve depolymerization of even the more recalcitrant MPs, biodeposits from mussels will be further processed in a microbially-driven Fenton bioreactor, and a complementary gradient microfluidic approach will be used to identify the optimal reaction conditions. At each stage of development, performance metrics will be quantified, alongside fundamental physiochemical properties, to inform a techno-economic optimization of a full-scale WWTP system that also incorporates a cost model for the socio-technical drivers/barriers to technology adoption. The expected outcomes of this project include (i) a detailed understanding of the fate of MPs in a model WWTP; (ii) practical, scalable processes to concentrate and eliminate MPs from wastewater, and (iii) decision tools to drive broad adoption of this MP separation and elimination technology.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.