Pyrolysis as an economical and ecological treatment option for municipal sewage sludge
Pyrolysis as an economical and ecological treatment option for municipal sewage sludge
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DOI：
10.1016/j.biombioe.2019.01.041
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发表时间：
2019-03-01
影响因子：
6
通讯作者：
Berruti, Franco
中科院分区：
文献类型：
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作者：
Barry, Devon;Barbiero, Chiara;Berruti, Franco
选择污水污泥热解作为提供生物炭和生物油的潜在处理方法。污水污泥的一个固有问题是保留在炭中的高浓度重金属。本研究旨在比较慢热解炭和快速热解炭及其对农业用地的重金属浸出率（根据美国 EPA 法规的规定）。缓慢热解生物炭产率从 300 摄氏度时的 51.6 wt% 下降到 500 摄氏度时的 32 wt%。同样，快速热解生物炭产率也从 400 摄氏度时的 30 wt% 下降到 500 摄氏度时的 26 wt%。由于灰分含量较高，高温下产生的炭的较高热值降低。快速热解炭在500℃时的无灰基础高位热值为34.6 MJ kg(-1)。我们开发了一种计算热解热函(2.2 MJ kg(-1))的新方法，用于为污水污泥热解建立完整的能量平衡。我们对每小时处理 2.1 吨干固体的典型污水污泥热解厂进行了经济分析。对于这样的场景，我们发现每年的总资本投资和年度支出分别为1350万加元和132万加元。环境生命周期评估确定，在水泥窑中使用生物炭作为替代燃料热解污水污泥对全球变暖潜力和淡水生态毒性的影响最小。
Pyrolysis of sewage sludge was selected as a potential disposal method that provides biochar and bio-oil. An intrinsic problem of sewage sludge is the high concentration of heavy metals, which is retained in the char. This study aims to compare both slow and fast pyrolysis char and their leachability of heavy metals for agricultural land use, as defined by the U.S. EPA regulation. Slow pyrolysis biochar yields decreased from 51.6 wt% at 300 degrees C to 32 wt% at 500 degrees C. Similarly, fast pyrolysis biochar yields also decreased from 30 wt% at 400 degrees C to 26 wt% at 500 degrees C. The higher heating value reduced for the chars produced at high temperatures because of greater ash content. The maximum higher heating value on ash free basis was 34.6 MJ kg(-1) for the fast pyrolysis char at 500 degrees C. We developed a new method for the calculation of the enthalpy of pyrolysis (2.2 MJ kg(-1)), which was used to create a complete energy balance for the pyrolysis of sewage sludge. We performed an economic analysis for a typical sewage sludge pyrolysis plant processing 2.1 ton of dry solids per hour. For such a scenario we found that the annual total capital investment and annual expenditure were 13.5 million CAD and 1.32 million CAD, respectively. An environmental life-cycle assessment determined that pyrolysis of sewage sludge with use of the biochar as a substitute fuel in a cement kiln had the least impacts on global warming potential and fresh water ecotoxicity.