title: A critical review on inhibition of anaerobic digestion process by excess ammonia.
abstract: Ammonia plays a vital role in the performance and stability of anaerobic digestion (AD) of N-rich organic-feedstock. Several research works were carried-out to study the effect of ammonia on the efficiency of AD of agro-food, industrial and livestock wastes/wastewater. However, excess ammonia remains a critical hitch in AD process. The mechanism of ammonia-inhibition has also been studied and there is no simple strategy available to mitigate ammonia-toxicity, when it exceeds threshold inhibition-level. For successful operation of AD systems at higher ammonia-level, adequate choice of temperature, control of pH and C/N ratio, and utilization of acclimatized-microflora to higher ammonia concentrations may ensure a stable and undisturbed digestion. This review provides a critical summary of earlier and recent research conducted on ammonia-inhibition during the anaerobic degradation of organic substrates, especially, at high ammonia concentrations. This article emphasizes that more profound knowledge on parameters influencing ammonia-inhibition is needed to apply appropriate control strategies.
authors.affiliation: Dairy and Swine Research and Development Center, Agriculture and Agri-Food Canada, Sherbrooke, Quebec J1M 0C8, Canada. rajinikanth.rajagopal@agr.gc.ca
authors.forename: Rajinikanth
authors.initials: R
authors.lastname: Rajagopal
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Massé
authors.forename: Gursharan
authors.initials: G
authors.lastname: Singh
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D000693:Anaerobiosis; D006863:Hydrogen-Ion Concentration; D013696:Temperature
chemical_list: D000641:Ammonia
keywords: Ammonia; Anaerobic digestion; Inhibition; Methanogens; Nitrogen