Comparative assessment of single-stage and two-stage anaerobic digestion for the treatment of thin stillage

A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from e...

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Bibliographic Details
Published in:Bioresource technology 2012-05, Vol.111, p.122-126
Main Authors: Nasr, Noha, Elbeshbishy, Elsayed, Hafez, Hisham, Nakhla, George, El Naggar, M Hesham
Format: Article
Language:English
Subjects:
Anaerobic digestion
Anaerobiosis
Biofuels
Byproducts
Crops, Agricultural - metabolism
Energy use
Ethyl alcohol
Fatty acids
Fatty Acids - metabolism
Hydrogen - metabolism
Methane
Methane - metabolism
Oxygen demand
Stillage
Volatile Organic Compounds - metabolism
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Summary:A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122 g/L and total volatile fatty acids (TVFAs) of 12 g/L. A maximum methane yield of 0.33 L CH(4)/gCOD(added) (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26 L CH(4)/gCOD(added) (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion.
ISSN:0960-8524
1873-2976
DOI:10.1016/j.biortech.2012.02.019