title: Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste.
abstract: This research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuously with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8 g/L, corresponding to 146 mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid.
authors.affiliation: Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, FR, Italy; UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands. Electronic address: jaka@unicas.it.
authors.forename: Javkhlan
authors.initials: J
authors.lastname: Ariunbaatar
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, Via Claudio 21, 80125 Naples, Italy.
authors.forename: Ester
authors.initials: E
authors.lastname: Scotto Di Perta
authors.affiliation: Telematic University PEGASO, Piazza Trieste e Trento, 48, 80132 Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Panico
authors.affiliation: Department of Mathematics and Applications Renato Caccioppoli, University of Naples Federico II, Via Claudio, 21, 80125 Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Frunzo
authors.affiliation: Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, FR, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Esposito
authors.affiliation: UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands.
authors.forename: Piet N L
authors.initials: PN
authors.lastname: Lens
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, Via Claudio 21, 80125 Naples, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pirozzi
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000693:Anaerobiosis; D056804:Biofuels / Q000032:analysis; D019149:Bioreactors; D005735:Garbage; D008697:Methane / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism*; D012037:Refuse Disposal / Q000379:methods*; D062611:Solid Waste / Q000032:analysis*
chemical_list: D056804:Biofuels; D062611:Solid Waste; D000641:Ammonia; D009584:Nitrogen; D008697:Methane
keywords: Ammonia inhibition; Anaerobic digestion; Buffer capacity; Comparison of one-stage and two-stage; Total ammoniacal nitrogen