Quantification and Analysis of Microplastics in Penn State Wastewater Systems

Open Access
Jackson, Andrew David
Area of Honors:
Civil Engineering
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Rachel Brennan, Thesis Supervisor
  • Eric Donnell, Honors Advisor
  • Microplastics
  • Cosmetic Microbeads
  • Penn State Wastewater
Plastics are a very useful material in industry and consumerism. However, the irreversible shredding of littered plastics into microscopic pieces smaller than 5 mm in diameter has endangered aquatic organisms and humans alike. Persistent organic pollutants (POP’s) and other contaminants have a tendency to sorb onto hydrophobic microplastics. When ingested by aquatic organisms, microplastics can be a source for contaminant bioaccumulation into humans. Microplastics also enter the environment through treated wastewater, which can contain synthetic fibers from clothing and polyethylene microbeads from cosmetic products. Microplastics have been quantified at a very wide range of concentrations in wastewater effluent, and very little is known about the behavior of microplastics in local environments immediately after release from wastewater treatment plants. The purpose of this thesis is to quantify and characterize the microplastics leaving the Penn State Wastewater Treatment Plant (PSU WWTP) and entering the Penn State Living Filter, the irrigation fields onto which the treated wastewater is sprayed. First, a sieve was used to collect particulate matter from the effluent of the PSU WWTP chlorine contact tank, which is the final stage of the treatment process. Then, 36 soil samples were collected from the Penn State Living Filter and a jar sedimentation process was used to separate plastics from sediments. Wet peroxide oxidation (WPO) was then used on all samples from both the PSU WWTP and the Living Filter to remove organic material from the samples, leaving only plastic and other synthetic materials. Ultimately, the concentration of plastic leaving the PSU WWTP was found to be 1 bead per 52 liters. This equates to roughly 146,000 beads per day entering the Penn State Living Filter. Additionally, a wide range of plastic concentrations were detected at the Penn State Living Filter wastewater irrigation fields, including plastics that were derived from plastic litter such as shotgun casings.