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Characterising and modelling free ammonia and ammonium inhibition in anaerobic systems
| Content Provider | Scilit |
|---|---|
| Author | Astals, S. Peces, M. Batstone, D. J. Jensen, P. D. Tait, S. |
| Copyright Year | 2018 |
| Description | Journal: Water research Inhibition by ammoniacal nitrogen, consisting of free ammonia $(NH_{3}$) and ammonium ion (NH_{4}$^{+}$), has been widely investigated for anaerobic digestion. However, despite the large amount of research on the subject, ammoniacal nitrogen inhibition still threatens many anaerobic digesters. This paper presents (i) a method to reliably characterise ammoniacal nitrogen inhibition and (ii) a robust inhibition modelling approach. Results showed that $NH_{3}$ and NH_{4}$^{+}$ inhibition need to be jointly determined, which can only be done by performing inhibition tests at various total ammoniacal nitrogen (TAN) concentrations and pH values. These test conditions were reliably achieved using the salts $NH_{4}HCO_{3}$ and $NH_{4}$Cl without pH adjustment, rather than by using $NH_{4}$Cl with pH adjustment. The use of only salts showed a lower pH change during the inhibition test (∼1.5 days), thereby decreasing the uncertainty in TAN speciation and strengthening the test and model outputs. A threshold inhibition function satisfactorily described $(R^{2}$ > 0.99) the joint inhibition of $NH_{3}$ and NH_{4}$^{+}$ on three distinct inocula, and provided a better description of the inhibition testing results than a non-competitive inhibition function $(R^{2}$ ∼0.70). The key advantage of the proposed threshold inhibition function is its capacity to identify the inhibition lower limit (concentration where inhibition starts; $KI_{min}$) and upper limit (concentration where inhibition is complete; $KI_{max}$). The threshold inhibition function also identifies the 50% inhibition concentration $(KI_{50}$) at the midpoint of $KI_{min}$ and $KI_{max}$. Finally, experimental and model results show that at pH 7.3–7.7 and TAN concentrations above 2000 $mgN·L^{−1}$, both $NH_{3}$ and NH_{4}$^{+}$ contribute significantly to overall inhibition. |
| Related Links | https://espace.library.uq.edu.au/view/UQ:1eb2161/UQ1eb2161_OA.pdf |
| Ending Page | 135 |
| Page Count | 9 |
| Starting Page | 127 |
| ISSN | 00431354 |
| DOI | 10.1016/j.watres.2018.06.021 |
| Journal | Water research |
| Volume Number | 143 |
| Language | English |
| Publisher | Elsevier BV |
| Publisher Date | 2018-10-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: Water research Water Science and Technology Anaerobic Digestion |
| Content Type | Text |
| Resource Type | Article |
| Subject | Ecological Modeling Waste Management and Disposal Pollution Environmental Engineering Water Science and Technology Civil and Structural Engineering |
