Biodegradation of Microplastics in Water Treatment

EPA Grant Number: SU840153
Title: Biodegradation of Microplastics in Water Treatment
Investigators: Lin, Xiaoxia “Nina”
Institution: University of Michigan
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2020 through November 30, 2021
Project Amount: $25,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2020) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources

Objective:

The goal of this project will be to determine the feasibility of engineering the microbiome of municipal wastewater treatment plants to degrade microplastics, before they enter the environment via discharge into surface waters or application of biosolids to agricultural fields. The prevention of microplastics pollution will benefit aquatic ecosystems, fishing and aquaculture industries, and human consumers of seafood. Enhanced biodegradation may be an inexpensive alternative for low-income communities which cannot afford upgraded tertiary treatment systems for their wastewater treatment plants to remove microplastics. Additionally, biodegradation of microplastics in sludge will mitigate some of the risks of using sludge in agricultural fields, thereby preventing inequitable pollution of rural areas with microplastics. Our approach is distinct from previous approaches involving plastic biodegradation in three respects: first, we will be investigating biodegradation and complete mineralization of plastics using microbial consortia instead of individual microbes; second, we will be using directed evolution to optimize microbial consortia instead of individual microbes; and third, we will optimize the indigenous microbiome  of wastewater treatment plants rather than introducing foreign microbes to wastewater treatment plants.

Approach:

To achieve our objectives, we will isolate indigenous consortia from local wastewater treatment plants and screen them for biodegradation of polyethylene and polyethylene terephthalate. We will enrich the isolated plastic-degrading consortia in synthetic wastewater media with the appropriate plastic, and then perform directed evolution and random mutagenesis experiments to improve the plastic degrading abilities of these consortia. At each stage, consortia will be characterized using metagenomic sequencing. Plastic biodegradation will be assessed qualitatively using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR), and quantitatively using a variety of techniques, including but not limited to respirometry. Plastic biodegradation pathways will be elucidated using carbon-13 (C-13) isotope tracing.

Expected Results:

Expected outputs include a methodology to optimize biodegradation capabilities of municipal wastewater treatment plants, an assessment of the feasibility of our approach, and an assessment of tradeoffs using an environmental input-output analysis. These outcomes will aid in the initial development of a risk assessment methodology for plastic biodegradation, for which risk assessment has not yet been performed. Expected outcomes include an improved understanding of how microbial consortia can improve human and environmental wellbeing via biodegradation of microplastics, a possible lower-cost alternative to tertiary wastewater treatment for the removal of microplastics, and increased awareness of microplastics pollution and plastic biodegradation among community members and wastewater treatment professionals. This will contribute to the mitigation of microplastics pollution to both aquatic and terrestrial ecosystems from communities and municipal wastewater treatment plants.

Supplemental Keywords:

Plastics, Microplastics, Wastewater Treatment, Microbial Consortia, Biodegradation, Directed Evolution, Microbiome, Aquatic