Purdue University Graduate School
Thesis_Final_Rackliffe 7.13.20.pdf (824.74 kB)

Effect of Acclimatization Rate on Biogas Production from Anaerobic Digestion of Biodiesel Waste Products

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posted on 2020-07-27, 18:36 authored by Jennifer A RackliffeJennifer A Rackliffe
Anaerobic digestion can be used to sustainably treat the organic byproducts of the biodiesel process (crude glycerol and biodiesel wastewater) while generating a renewable natural gas to be used for heating or electricity generation. The purpose of this thesis was to (1) investigate the possibility of co-digestion of biodiesel byproducts without use of external substrates or pretreatment and (2) assess the impact of various acclimatization rates on the stability and efficiency of such a system. Two inocula (effluent from a wastewater treatment plant digester and from an agro-industrial waste digester) and two acclimatization rates were studied. The results showed that co-digestion of crude glycerol and biodiesel wastewater at high organic loading rates(up to 6.8 g COD L-1day-1)is possible without addition of other substrates or pretreatment.Thecumulative biogas production of the digesters using inoculum from the agro-industrial waste digester was statistically greater than the digesters using the wastewater treatment plant digester, indicating that similar inoculum could be useful for additional experiments.In addition,maximum efficiency due to a slower rate of acclimatization was higher for both inocula, up to a maximum average daily biogas yield of 621 mL biogas g-1COD added.Finally, comparison of two methods for measuring gas production (mass difference and volumetrically using a syringe) revealed a reasonable correlation(R2= 0.97)between the methods. Additional validation could lead to use of the mass difference method as a validation method or an alternative gas production measurement method.


Degree Type

  • Master of Science in Agricultural and Biological Engineering


  • Agricultural and Biological Engineering

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Dr. Nathan S. Mosier

Additional Committee Member 2

Dr. Jiqin Ni

Additional Committee Member 3

Dr. Eduardo A. Ximenes

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