Factors affecting Nitrogen Transformations and Related Nitrous Oxide Emissions from Aerobically Treated Piggery Slurry

✍ Scribed by F. Béline; J. Martinez; D. Chadwick; F. Guiziou; C.-M. Coste

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 291 KB
• Volume: 73
• Category: Article
• ISSN: 0021-8634
• DOI: 10.1006/jaer.1999.0412

✦ Synopsis

A laboratory treatment system was designed to study the fate of nitrogen during aerobic treatment of pig slurry. Di!erent aeration strategies, and more particularly the in#uence of residence time and aeration level, were manipulated. A series of six experiments was carried out to determine the nitrogen mass balance, including measurement of the gaseous nitrogen forms particularly ammonia and nitrous oxide. Further nitrogen transformations were examined during the subsequent anaerobic storage of aerated pig slurry at 7, 21 and 60 days. Aeration level and carbon content of raw slurry were identi"ed as the main factors in#uencing nitrogen transformation during treatment. A high aeration level (2}4 mg O /l) and/or low carbon content (biological oxygen demand of the raw slurry +2 g/kg) resulted in nitrite accumulation (up to 33% of the total nitrogen content of the raw slurry) while a low level of aeration (redox potential"0 mV !

) and high carbon content (biological oxygen demand of the raw slurry +16 g/kg) led to simultaneous nitri"cation and denitri"cation which removed 66% of the total nitrogen in the raw slurry. Nitrous oxide emissions were observed in all treatments and represent up to 30% of the total nitrogen content of the raw slurry. Both nitri"cation and denitri"cation appear to be sources of nitrous oxide during the treatment. Further nitrous oxide emissions were recorded during subsequent storage, especially when the biological oxygen demand to NO\ V -N ratio was lower than 1)3. However, during closed storage experiments, the nitrous oxide emitted was dissolved into the slurry and "nally reduced to di-nitrogen after 60 days of storage.