Civil Engineering ETDs

Publication Date

Fall 12-16-2017


Plastic biofilm carriers are used in biological wastewater treatment to encourage the attachment and retention of microorganisms that metabolize pollutants. The following research was conducted to better understand how different characteristics of the biofilm carrier affect the treatment performance of the attached biofilms in moving bed bioreactors. Lab scale reactors were used in this study to grow nitrifying biofilms in reactors with contrasting and controlled conditions. The effect of surface geometry on nitrification performance was evaluated by testing commercially available moving bed bioreactor media that contrast in physical design, and by varying operational parameters. Additionally, mature biofilm from a similar attachment media type were tested under nitrification-inhibited conditions to better understand microbial populations and metabolisms associated with organic microconstituent removal. Finally, the influence of surface chemistry on biofilm attachment and performance was tested by facilitating biofilm growth on freely floating nylon and high-density polyethylene. Results indicate that organisms grown on more protected, sheltered carrier media respond to changes in mixing more rapidly than those on open and exposed media design. Geometry of the carrier media in a well mixed freely floating reactor influences the environment of the biofilm as it determines the fluid dynamics experienced by the microorganisms. In biofilm systems designed to remove organic microconstituents, the occurrence of nitrification appears to have benefits for the removal of several different compounds. The type of plastic used to attach biofilms may also influence the total quantity or relative abundance of bacteria types and the performance of microconstituent removal.


nitrification, wastewater, biofilms


National Science Foundation

Document Type




Degree Name

Civil Engineering

Level of Degree


Department Name

Civil Engineering

First Committee Member (Chair)

Andrew Schuler

Second Committee Member

Bruce Thomson

Third Committee Member

Kerry Howe

Fourth Committee Member

Carlo Santoro