Effect of different ammonia sources on aceticlastic and hydrogenotrophic methanogens

Research output: Contribution to journalJournal article – Annual report year: 2018Researchpeer-review



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Ammonium chloride (NH4Cl) was usually used as a model ammonia source to simulate ammonia inhibition during anaerobic digestion (AD) of nitrogen-rich feedstocks. However, ammonia in AD originates mainly from degradation of proteins, urea and nucleic acids, which is distinct from NH4Cl. Thus, in this study, the inhibitory effect of a “natural” ammonia source (urea) and NH4Cl, on four pure methanogenic strains (aceticlastic: Methanosarcina thermophila, Methanosarcina barkeri; hydrogenotrophic: Methanoculleus bourgensis, Methanoculleus thermophilus), was assessed under mesophilic (37 °C) and thermophilic (55 °C) conditions. The results showed that urea hydrolysis increased pH significantly to unsuitable levels for methanogenic growth, while NH4Cl had a negligible effect on pH. After adjusting initial pH to 7 and 8, urea was significantly stronger inhibitor with longer lag phases to methanogenesis compared to NH4Cl. Overall, urea seems to be more toxic on both aceticlastic and hydrogenotrophic methanogens compared to NH4Cl under the same total and free ammonia levels.

Original languageEnglish
JournalBioresource Technology
Pages (from-to)390-397
Publication statusPublished - 2018
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Ammonia inhibition, Ammonium chloride, Anaerobic digestion, Pure strain, Urea

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