Emission and control of N₂O and composition of ash derived from cattle manure combustion using a pilot-scale fluidized bed incinerator

Abstract

This study investigates the emission of nitrous oxide (N₂O) and discusses the reduction of N₂O emissions during the 24-h combustion of cattle manure using a pilot-scale fluidized bed incinerator under various experimental conditions. The results of these experiments were then validated against previously reported data. In addition, the characteristics of cattle manure incineration ash and their changes under different combustion conditions were estimated. In incineration experiments with composted cattle manure, N₂O concentrations using multi-stage combustion were 75% lower than the concentrations resulting from normal combustion without additional auxiliary fuel, since N₂O could be decomposed in the high-temperature zone formed by the inlet of the secondary combustion air. The N₂O emission factor under normal combustion conditions (800°C) was 6.0% g-N₂O-N/g-N. This result is similar to the values found in previous studies at the same temperature. The N₂O emission factor was decreased to 1.6% g-N₂O-N/g-N using a multi-stage combustion procedure. The current Japanese N₂O emission factor of 0.1% g-N₂O-N/g-N is an underestimate for some conditions and should be uniquely specified for each condition. Finally, cattle manure ash contains ample fertilizer elements, little Fe, Al and Zn, but abundant Cl. Therefore if Cl could be removed by some kind of pretreatment, cattle manure ash could be used as a favourable fertilizer.

Keywords:

• nitrous oxide
• combustion
• cattle manure
• emission factor
• phosphorus

Acknowledgment

The cattle manure incineration experiment was supported by Mr Tetsuya Yanase, Mr Masayuki Yamamoto, Mr Tomoyuki Takeshita, Mr Shusaku Hattori, Mr Yoichiro Mizuno, and the members of the Environmental System Development Division, R&D Center, METAWATER Co., Ltd.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Japan Science and Technology Agency (JST/CREST).