State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, SKLUWRE, HIT, Harbin 150090, China.
Environ Sci Technol. 2013 Apr 2;47(7):3498-505. doi: 10.1021/es304248j. Epub 2013 Mar 20.
The nitrogen conversions in relation to NH3 and HCN were investigated during microwave pyrolysis of sewage sludge. The nitrogen distributions and evolution of nitrogen functionalities in the char, tar, and gas fractions were conducted. The results suggested that the thermal cracking of protein in sludge produced three important intermediate compounds, including the amine-N, heterocyclic-N, and nitrile-N compounds. The deamination of amine-N compounds resulted from labile proteins cracking led to the formation of NH3 (about 7.5% of SS-N) between 300 and 500 °C. The cracking of nitrile-N and heterocyclic-N compounds in the tars from the dehydrogenation and polymerization of amine-N generated HCN (6.6%) from 500 to 800 °C, respectively. Moreover, the ring-opening of heterocyclic-N in the char and tar contributed to the release of NH3 accounting for about 18.3% of SS-N with the temperature increasing from 500 to 800 °C. Specifically, the thermal cracking of amine-N, heterocyclic-N and nitrile-N compounds contributed to above 80% of the total (HCN+NH3) productions. Consequently, it might be able to reduce the HCN and NH3 emissions through controlling the three intermediates production at the temperature of 500-800 °C.
在污水污泥的微波热解过程中，研究了与 NH3 和 HCN 相关的氮转化。对炭、焦油和气体馏分中的氮分布和氮官能团的演变进行了研究。结果表明，污泥中蛋白质的热裂解产生了三种重要的中间化合物，包括胺-N、杂环-N 和腈-N 化合物。胺-N 化合物的脱氨作用是由不稳定蛋白质裂解产生的，导致 300-500°C 之间形成 NH3（约 SS-N 的 7.5%）。在来自胺-N 脱氢和聚合的焦油中的腈-N 和杂环-N 化合物的裂解分别在 500-800°C 之间产生 HCN（6.6%）。此外，杂环-N 在炭和焦油中的开环有助于随着温度从 500°C 升高到 800°C，NH3 的释放，占 SS-N 的约 18.3%。具体而言，胺-N、杂环-N 和腈-N 化合物的热裂解导致了总（HCN+NH3）产量的 80%以上。因此，通过控制 500-800°C 温度下这三种中间体的生成，可能能够减少 HCN 和 NH3 的排放。
