Civil Engineering

 

First Advisor

Ashraf Aly Hassan

Second Advisor

Bruce Dvorak

Date of this Version

5-2019

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor Ashraf Aly Hassan and Professor Bruce Dvorak. Lincoln, Nebraska: May, 2019.

Copyright (c) 2019 Christopher Arthur Duerschner

Abstract

Ethanol manufacturing is an important and growing sector in the biofuels marketplace. At ethanol plants, the control of volatile organic compound containing emissions from fermentation tanks and distillers dried grains with solubles driers is accomplished through the use of air scrubbers and regenerative thermal oxidizers. The operation of these control units imposes substantial operating costs for the ethanol plant. Biotrickling filters have the ability to replace scrubbers and regenerative thermal oxidizers resulting in significant economic and environmental benefits. Two biotrickling filters were operated in parallel under acetaldehyde loadings ranging from 4 to 136 gm-3hr-1. To examine the effect of temperature on the effectiveness of treatment, one of the biotrickling filters was operated at room temperature while the other one was heated to 60°C – the expected exit temperature of drier emissions. The unheated biotrickling filter reached an elimination capacity of 112 gm-3hr-1 at a removal efficiency of 83.2% and 31-seconds empty bed residence time. A removal efficiency of 100% was maintained up to a loading rate of 45.28 gm-3hr-1. The heated biotrickling filter reached an elimination capacity of 27.6 gm-3hr-1 at a loading rate of 38.4 gm-3hr-1. While high removal was achieved at low loading rates, removal suffered significantly at higher influent concentrations. Performance of the heated biotrickling filter was improved by reseeding with cooking compost resulting in increased thermophilic bacterial population. The main biodegradation byproduct formed was acetic acid with traces of formic acid. Mathematical modelling was used to successfully describe acetaldehyde concentration profiles.

Advisors: Bruce I. Dvorak and Ashraf Aly Hassan

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