Nitrogen Conversion in Relation to NH3 and HCN during Microwave Pyrolysis of Sewage Sludge

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• 作者：Yu Tian ; Jun Zhang ; Wei Zuo ; Lin Chen ; Yanni Cui ; Tao Tan
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：April 2, 2013
• 年：2013
• 卷：47
• 期：7
• 页码：3498-3505
• 全文大小：366K
• 年卷期：v.47,no.7(April 2, 2013)
• ISSN：1520-5851

文摘

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 掳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 掳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 掳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鈥?00 掳C.