Investigating the effectiveness of microplastic removal and the relationship between microplastics, bacterial communities, and nitrogen cycling in the natural treatment systems at the Arcata Wastewater Treatment Facility
Master of Science degree with a major in Environmental Systems, option Environmental Resources Engineering
Committee Chair Name
Eileen Cashman (Co-Chair)
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Catalina Cuellar-Gempeler (Co-Chair)
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Third Committee Member Affiliation
Community Member or Outside Professional
Environmental Resources Engineering
This thesis addressed two challenging aspects of microplastic research, including the quantification of microplastics in organic-rich water, and the investigation of how microplastics impact microorganisms and related nutrient-cycling. Two projects were designed and executed to address specific research objectives relating to these broad topics. The first objective was to develop and implement methods to determine the effectiveness of microplastic removal across the natural treatment systems at the Arcata Wastewater Treatment Facility (AWTF). The second objective was to observe how microplastics found in domestic wastewater impact the bacterial communities and nitrogen cycling in freshwater treatment wetland sediment through a bench-scale experiment, modelled after Seeley et al. (2020). The objectives for both parts of this study were successfully met. Methods were developed to sample large volumes of AWTF water and determine microplastic concentrations. Compared to the Primary Clarifier effluent, there is a greater than 99% reduction of microplastics in the Oxidation Ponds, with no further net removal in the Treatment Wetlands or Enhancement Wetlands. From the bench-scale experiment, it was determined that polyamide microplastics, commonly found in domestic wastewater, significantly impact freshwater marsh sedimentary bacterial communities and related nitrogen cycling. Overall, results indicate that a high load of microplastics is accumulating in the Oxidation Ponds and that those microplastics have the potential to impact nitrogen cycling and ammonia treatment.
Connor, Fiona, "Investigating the effectiveness of microplastic removal and the relationship between microplastics, bacterial communities, and nitrogen cycling in the natural treatment systems at the Arcata Wastewater Treatment Facility" (2023). Cal Poly Humboldt theses and projects. 650.