Degree Type

Thesis

Date of Award

2007

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Robert C. Brown

Abstract

This thesis is an exploration into the technical and economic issues related to a syngas fermenting biorefinery producing 50 metric tons per day of hydrogen gas and 12 metric tons per day of PHA, a biodegradable plastic. In addition, an optimization study on the bioreactor is performed by varying reactor diameter and stirring speed.;The analysis assumed switchgrass costing {dollar}55/Mg as feedstock, and the bacterium Rhodospirillum rubrum to ferment the syngas. With a hydrogen market value of {dollar}1.90/kg assumed, 95% pure PHA was determined producible for approximately {dollar}2.05/kg. Grassroots capital for the biorefinery was estimated to be {dollar}55 million, with annual operating costs at {dollar}8.3 million. For a constant volumetric mass transfer coefficient of 0.05 s-1 the optimum reactor size was a 14.8 m diameter being stirred at 0.6 rev/s. Producing PHA by this method was found to be less expensive than processes using sugar fermentation.

DOI

https://doi.org/10.31274/rtd-180813-15834

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Scott C. Bents

Language

en

Proquest ID

AAI1447501

OCLC Number

213358331

ISBN

9780549334422

File Format

application/pdf

File Size

100 pages

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