Nitrous oxide production during nitrification from organic solid waste under temperature and oxygen conditions
2016
Nag, Mitali | Shimaoka, Takayuki | Komiya, Teppei
Landfill aeration can accelerate the biological degradation of organic waste and reduce methane production; however, it induces nitrous oxide (N ₂O), a potent greenhouse gas. Nitrification is one of the pathways of N ₂O generation as a by-product during aerobic condition. This study was initiated to demonstrate the features of N ₂O production rate from organic solid waste during nitrification under three different temperatures (20°C, 30°C, and 40°C) and three oxygen concentrations (5%, 10%, and 20%) with high moisture content and high substrates’ concentration. The experiment was carried out by batch experiment using Erlenmeyer flasks incubated in a shaking water bath for 72 h. A duplicate experiment was carried out in parallel, with addition of 100 Pa of acetylene as a nitrification inhibitor, to investigate nitrifiers’ contribution to N ₂O production. The production rate of N ₂O ranged between 0.40 × 10 ⁻³ and 1.14 × 10 ⁻³ mg N/g-DM/h under the experimental conditions of this study. The rate of N ₂O production at 40°C was higher than at 20°C and 30°C. Nitrification was found to be the dominant pathway of N ₂O production. It was evaluated that optimization of O ₂ content is one of the crucial parameters in N ₂O production that may help to minimize greenhouse gas emissions and N turnover during aeration.
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