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Civil and Environmental Engineering

Doctoral Dissertations

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Response Of Microbial Community Structure To Clay Flocculation Of Harmful Algal Blooms, Chunyi Chen May 2016

Response Of Microbial Community Structure To Clay Flocculation Of Harmful Algal Blooms, Chunyi Chen

Doctoral Dissertations

Harmful algal blooms are cosmopolitan and can produce extremely dangerous toxins that can sicken or kill people and animals, and create dead zones in the water. The U.S. economic loss caused by algal blooms is $82 million every year. Clay-based flocculation techniques have been developed to mitigate algal blooms; however, the potential impacts on the microbial community are poorly understood. This dissertation includes multi-scale experiments (Jar, field, microcosms) to study the response of microbial community structure and function to clay flocculation of algal blooms.

Jar tests of removal of Microcystis aeruginosa by chitosan and two types of commercially available clays …


Toward Understanding The Physiological Determinants Of Microbial Competitiveness In Methanogenic Processes, Si Chen Dec 2014

Toward Understanding The Physiological Determinants Of Microbial Competitiveness In Methanogenic Processes, Si Chen

Doctoral Dissertations

Methanogenesis is of great significance in both natural and engineered processes. Anaerobic digestion technology represents the engineering-scale implementation of methanogenesis in waste treatment processes. Despite the broad application of anaerobic digestion as a common waste treatment option, much remains to be learned on the anaerobic food web underlying methanogenesis for more effective process modeling and control.

Following an initial screening of various substrates, six continuous lab-scale anaerobic digesters were developed with animal waste as the substrate. The linkage between microbial community composition and process performance was studied by initiating process imbalance with organic overloading. As a result, accumulation of short …