Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, FR (Italy)
- Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, Via Claudio 21, 80125 Naples (Italy)
- Telematic University PEGASO, Piazza Trieste e Trento, 48, 80132 Naples (Italy)
- Department of Mathematics and Applications Renato Caccioppoli, University of Naples Federico II, Via Claudio, 21, 80125 Naples (Italy)
- UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft (Netherlands)
Highlights: • Almost 100% of the biomethane potential of food waste was recovered during AD in a two-stage CSTR. • Recirculation of the liquid fraction of the digestate provided the necessary buffer in the AD reactors. • A higher OLR (0.9 gVS/L·d) led to higher accumulation of TAN, which caused more toxicity. • A two-stage reactor is more sensitive to elevated concentrations of ammonia. • The IC{sub 50} of TAN for the AD of food waste amounts to 3.8 g/L. - 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.
- OSTI ID:
- 22470229
- Journal Information:
- Waste Management, Vol. 38; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACID NEUTRALIZING CAPACITY
AMMONIA
ANAEROBIC DIGESTION
CARBOXYLIC ACIDS
CONCENTRATION RATIO
ENERGY CONVERSION
FOOD
METHANE
NITROGEN
PH VALUE
PROPIONIC ACID
TOXICITY
VOLATILITY
WASTES