Civil and Environmental Engineering


First Advisor

Ashraf Aly Hassan

Second Advisor

Bruce Dvorak

Date of this Version

Summer 7-30-2020


Al-Faliti, M. (2020). "Biofiltration of Volatile Organic Compounds Emitted at Ethanol Plants." University of Nebraska - Lincoln, Nebraska, United States. Thesis.


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: Environmental Engineering, Under the Supervision of Professor Ashraf Aly Hassan and Professor Bruce Dvorak. Lincoln, Nebraska: August, 2022

Copyright 2020 Mitham Al-Faliti


Ethanol is a major biofuel source of energy in the U.S. Ethanol production produces several harmful emissions from both fermentation tanks and dryers. CO2 scrubbers control the emissions from the fermentation tanks, while the emissions from the dryers are controller by regenerative thermal oxidizers. These methods are expensive to operate. A potential alternative is bio-trickling filters. Bio-trickling filters are an inexpensive and environmentally friendly alternative. For this study, two parallel bio-trickling filters were operated one at 25°C called the mesophilic bio-trickling filter and one at 60°C called the thermophilic bio-trickling filter. The mesophilic bio-trickling filter simulates emissions from fermentation tanks while the thermophilic bio-trickling filter simulates emissions from dryers. The two beds were operated at an empty bed residence time of 31.3s. The beds were operated at three phases where phase I, II, and III correspond to influent formaldehyde concentrations of 20, 50, and 100 parts per million per volume, respectively. No maximum elimination capacity was established for this study; however, the highest recorded elimination capacity was 60 g m-3 h-1 for the mesophilic and 41.9 g m-3 h-1 for the thermophilic bio-trickling filters, respectively. Formaldehyde polymerization was also reduced in this study by adding NaOH to pH levels of 7.0-7.4 and heating the solution to a temperature of 60°C. Methanol biodegradation was also investigated in this study. The highest elimination capacities for methanol for both mesophilic and thermophilic BTFs are 13.0 and 11.3 g m-3 h-1. Acetaldehyde biodegradation in a BTF was compared between three different temperature of 20, 40, and 60°C at a loading rate of 45.3 g m-3 h-1. The BTF at 40°C performed better reaching an elimination capacity of 44.2 g m-3 h-1. Finally, a calibration curve for the dervatization and quantification of formaldehyde was successfully established up to a concentration of 10 ppmv.

Advisors: Ashraf Aly Hassan and Bruce Dvorak