Degree Type

Thesis

Date of Award

2013

Degree Name

Master of Science

Department

Agricultural and Biosystems Engineering

First Advisor

Kurt A. Rosentrater

Abstract

With the rapid development of the ethanol industry, various research on distillers dried grains with solubles (DDGS) as a main co-product from the ethanol industry has been done in recent years. However, related research about basic properties to DDGS lacks of comprehensiveness. In addition, the efficient method and equipment to separate DDGS to high-valued fraction is still being investigated. Besides these, the possibility about using DDGS to produce ethanol is being explored, which is designed to own the advantages of comprehensiveness and systematicness.

This thesis is prepared in paper format, and is comprised of three manuscripts, as follow: the first part was to examine 18 samples from 10 plants in Midwest area and utilize standard laboratory methods to measure a series of properties. Final results showed moisture content of 8.69% (w.b.), water activity of 0.55, angle of repose of 48.04 º, geometric mean diameter (dgw) of 0.74 mm, geometric standard deviation (Sgw) of 1.72 mm, loose bulk density of 483.9 kg/m3, packed bulk density of 568.5 kg/m3, Hunter L of 56.71, Hunter a of 13.85, Hunter b of 46.51, shear strength of 0.0324 kg/cm2. So it represents another step toward a complete baseline understanding of DDGS.

The second part was to use a destoner fractionation process for separating distillers dried grains with solubles (DDGS) into streams with various compositions. Results showed that destoner fractionation was somewhat efficient and effective. Runs with 8° angle and 27.5 percent air flow resulted in the highest value of protein and oil, which the light fraction had 28.15% protein, 10.50% oil, while the heavy fraction had 31.30% protein and 17.20% oil. Particle size distribution had a positive correlation coefficient (0.93) with oil parameters and a negative correlation coefficient (-0.96) with moisture parameters. Fiber had no relationship with particle size, and protein had a weak correlation coefficient with (-0.54) to particle size.

The third part described to use low-moisture anhydrous ammonia (LMAA) to pretreat DDGS and discussed varieties conditions to optimize the reaction. In previous research, low-moisture anhydrous ammonia (LMAA) pretreatment was investigated due to its high efficiency and less washing compared to other pretreatment methods. The final result showed that lower ammonia loading rate, higher moisture content, higher temperature and longer pretreatment time is evidently to improve the effect of ammonia to break lignocelluloses structure in DDGS, which can improve the hydrolysis of enzyme. Optimal LMAA conditions for DDGS were 80° C, 60% moisture content and 0.1 kg anhydrous NH3/kg dry biomass with a 168h pretreatment time. Also comparing with other methods, LMAA to DDGS has a higher efficiency and environmental conservation, which is potentially fit for industry produce. In the future study, the financial analysis to this method will be done to discuss the possibility of LMAA in industry produce.

Copyright Owner

Weitao Zhang

Language

en

File Format

application/pdf

File Size

116 pages

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