Modelling sodium inhibition on the anaerobic digestion process

Joseph C. Akunna, Anthony Hierholtzer

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Sodium is a known process inhibitor in anaerobic systems and impacts on methanogens through an increase of osmotic pressure or complete dehydration of microorganisms. In this study, a combination of experimental and modelling approaches has been employed to determine and simulate sodium inhibition on the anaerobic digestion process. The ADM1, which has been successfully used in modelling anaerobic processes, has been modified to include an extra inhibition function that considers the effect of sodium on acetoclastic methanogens and the impact on biogas production and composition. A non-competitive inhibition function was added to the rate of acetate uptake for the model to take into account sodium toxicity. Experimental studies consisted of both batch and reactor tests to obtain parameters for model calibration and validation. The calibrated model was used to predict the effect of ammonia nitrogen on sodium toxicity. It was found that relatively low sodium levels can bring about significant levels of process inhibition in the presence of high levels of ammonia. On the other hand, where the concentration of ammonia is relatively low, the tolerance threshold for sodium ions increases. Hence, care must be taken in the use of sodium hydroxide for pH adjustment during anaerobic digestion of protein-rich substrates.
Original languageEnglish
Pages (from-to)1565-1573
Number of pages9
JournalWater Science and Technology
Volume66
Issue number7
DOIs
Publication statusPublished - 2012

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sodium
modeling
ammonia
toxicity
anaerobic digestion
biogas
dehydration
hydroxide
inhibitor
acetate
experimental study
tolerance
microorganism
calibration
substrate
protein
ion
nitrogen

Cite this

Akunna, Joseph C. ; Hierholtzer, Anthony. / Modelling sodium inhibition on the anaerobic digestion process. In: Water Science and Technology. 2012 ; Vol. 66, No. 7. pp. 1565-1573.
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Modelling sodium inhibition on the anaerobic digestion process. / Akunna, Joseph C.; Hierholtzer, Anthony.

In: Water Science and Technology, Vol. 66, No. 7, 2012, p. 1565-1573.

Research output: Contribution to journalArticle

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AB - Sodium is a known process inhibitor in anaerobic systems and impacts on methanogens through an increase of osmotic pressure or complete dehydration of microorganisms. In this study, a combination of experimental and modelling approaches has been employed to determine and simulate sodium inhibition on the anaerobic digestion process. The ADM1, which has been successfully used in modelling anaerobic processes, has been modified to include an extra inhibition function that considers the effect of sodium on acetoclastic methanogens and the impact on biogas production and composition. A non-competitive inhibition function was added to the rate of acetate uptake for the model to take into account sodium toxicity. Experimental studies consisted of both batch and reactor tests to obtain parameters for model calibration and validation. The calibrated model was used to predict the effect of ammonia nitrogen on sodium toxicity. It was found that relatively low sodium levels can bring about significant levels of process inhibition in the presence of high levels of ammonia. On the other hand, where the concentration of ammonia is relatively low, the tolerance threshold for sodium ions increases. Hence, care must be taken in the use of sodium hydroxide for pH adjustment during anaerobic digestion of protein-rich substrates.

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