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University of Massachusetts Amherst

Environmental Engineering

EPS

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Full-Text Articles in Engineering

The Role Of Extracellular Polymeric Substances In The Accumulation And Transport Of Polystyrene Nanoparticles In Biofilms, Joann Marie Rodríguez Suarez Mar 2022

The Role Of Extracellular Polymeric Substances In The Accumulation And Transport Of Polystyrene Nanoparticles In Biofilms, Joann Marie Rodríguez Suarez

Doctoral Dissertations

With the increasing number of nanotechnology applications, it is reasonable to expect nanoparticles to be ubiquitous in biofilms found in natural and engineered aquatic systems. We studied the impact of the degree of cross-linking on the deposition and diffusion of polystyrene nanoparticles (NPs) in alginate model biofilm matrices in the presence and absence of calcium cross-linkers using image correlation methods and single particle tracking. We found that cross-linking increases the viscoelasticity and hydration of the polymeric matrix and leads to structural changes that can restrict and alter the diffusive behavior of NPs, but the magnitude of the effects on diffusion …


Size Progression Of Oxygenic Photogranules (Opgs) And Its Effect On Opg Wastewater Treatment, Ahmed S.A. Abouhend Feb 2022

Size Progression Of Oxygenic Photogranules (Opgs) And Its Effect On Opg Wastewater Treatment, Ahmed S.A. Abouhend

Doctoral Dissertations

In recent years, the oxygenic photogranule (OPG) process has gained increasing interest because of its potential to treat wastewater without supplemental aeration. Oxygenic photogranules (OPGs) are dense spherical aggregates comprised of phototrophic and nonphototrophic microorganisms. In OPG wastewater treatment reactors, photogranules grow in number as well as in size. The primary goal of this dissertation was to investigate how OPGs grow in size and how the growth affects their structure and functions. We found that OPGs undergo structural changes as they grow bigger in size. As OPGs grow larger, filamentous cyanobacteria become enriched while other phototrophic microbes diminish significantly. OPGs …