Study on release of polycyclic aromatic hydrocarbons during sewage sludge pyrolysis

doi:10.11949/j.issn.0438-1157.20180018

Abstract

Abstract:

The production and distribution of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) in liquid, gas and solid three-phase products from sewage sludge pyrolysis from 350 to 1050℃ were studied. The results show that PAHs tend to be concentrated in liquid product, then into gaseous and solid products. The mass ratio of 16 kinds of PAHs contained in liquid product reaches the highest value 96% at 650℃. 16 kinds of EPA-PAHs in liquid products are all detected out. The mass ratio of ∑₁₆PAHs in gas phase products at 750℃ reaches the highest value, 21.3%. The content of PAHs in solid product is very low, which is 1%. At all the targeted pyrolysis temperatures, 2, 3 and 4 rings of PAHs occupied a leading position in the resulting products. The mass ratio of ∑_2,3,4 rings of PAHs was over 95%, and the highest content of EPA-PAHs in liquid phase products is 15.25 mg·kg^-1 at 850℃. In the gas phase, it mainly contains naphthalene (NaP), acenaphthylene (Acp), fluorene (Flu) and anthracene (Ant), and the high ring of PAHs are not detected out. During a high temperature sludge pyrolysis, the thermos-chemical reaction of large molecular structure reaches a peak, along with the functional-groups decomposition, synthesis, and cyclization reactions, the concentration of ∑_low PAHs in gas product reached 7.248 mg·kg^-1. The variation of PAHs TEQ in the pyrolysis products from different temperatures basically agrees their concentration distributions. The TEQ of PAHs in the liquid product is up to 1.129 at 850℃.

Key words: sewage sludge, pyrolysis, liquid product, gas product, polycyclic aromatic hydrocarbons

摘要：

研究了不同温度（350~1050℃）下污泥热解过程液、气、固三相产物中16种多环芳烃（PAHs）排放规律。结果表明，PAHs趋向富集于液相产物中，其次为气相产物，在液相产物中检测到所有16种PAHs，650℃液相产物中16种PAHs（∑₁₆PAHs）总质量比最高，为96%；750℃气相产物中∑₁₆PAHs质量比最高，为21.3%以上；固相产物中PAHs含量极少，仅在650℃时达1%。所有温度下液相产物中2、3和4环PAHs均占据主导地位，∑_2，3，4环PAHs质量比达95%以上，850℃时液相产物中∑EPA-PAHs含量最高，达15.25 mg·kg^-1。气相产物主要以萘（NaP）、苊烯（Acp）、芴（Flu）和蒽（Ant）PAHs为主，未检测到高环PAHs。在高温热解阶段，污泥大分子结构裂解到达高峰，伴随产物的二次断裂、合成、环化等反应，气相产物中∑_低PAHs生成含量达到最高7.248 mg·kg^-1。不同温度下污泥热解产物中PAHs的毒性当量（TEQ）变化规律与其生成量变化基本一致，在850℃时液相产物中PAHs的TEQ最高达1.129。

关键词: 污泥, 热解, 液相, 气相, 多环芳烃

CLC Number:

TQ541

HU Yanjun, YU Fan, CHEN Jiang, YU Wenjing, LU Yanjun. Study on release of polycyclic aromatic hydrocarbons during sewage sludge pyrolysis[J]. CIESC Journal, 2018, 69(8): 3662-3669.

胡艳军, 余帆, 陈江, 于文静, 卢艳军. 污泥热解过程中多环芳烃排放规律[J]. 化工学报, 2018, 69(8): 3662-3669.

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