Combustion of sewage sludge has become a viable route for sewage sludge management especially as the agricultural use of sewage sludge has become increasingly difficult due to more stringent requirements regarding the quality of sewage sludge. Combustion of digested sewage sludge in dedicated monocombustion facilities is advantageous, as it substantially reduces the volume of the sludge and still allows for a recovery of phosphorus from the sewage sludge ash at a later stage. Despite increasing amounts of sewage sludge being combusted, knowledge on the respective combustion kinetics is still fragmentary. The goal of this study was, therefore, to identify the major combustion reactions of sewage sludge, assess their Arrhenius parameters (activation energy and pre-exponential factor), and assign suitable reference compounds to the individual reactions. For that purpose, experiments were conducted using a thermogravimetric analyzer (TGA). With matrix inversion, we identified 10 individual reactions. Despite the apparent kinetic compensation most likely caused by insufficient precision of the TGA temperature setting, we were able to relate the major reactions of sewage sludge combustion to the combustion of individual reference compounds. In addition to cellulose and lignin, which dominated the weight loss with 35% and 20%, respectively, hemicellulose, xylan, alginate, and calcite were identified. The dominant fraction of cellulose is consistent with recent studies identifying cellulose mainly originating from toilet paper as a major organic constituent in wastewater. As the identified model compounds explain more than 80% of the total weight loss observed, our approach allows a rough speciation of the combustibles of sewage sludge based on TGA experiments.

中文翻译：

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污泥的燃烧：可燃物的动力学和形态

污水污泥的燃烧已成为污水污泥管理的可行途径，尤其是由于对污水污泥质量的更严格要求，农业污水污泥的使用变得越来越困难。消化的污水污泥在专用的单燃烧设施中的燃烧是有利的，因为它大大减少了污泥的体积，并且仍然允许在以后的阶段从污水污泥灰中回收磷。尽管燃烧的污水污泥数量增加，但是关于各自的燃烧动力学的知识仍然是零碎的。因此，本研究的目的是确定污水污泥的主要燃烧反应，评估其Arrhenius参数（活化能和指数前因子），并为各个反应分配合适的参考化合物。为此，使用热重分析仪（TGA）进行了实验。通过矩阵求逆，我们确定了10个独立反应。尽管明显的动力学补偿很可能是由TGA温度设置的精度不足引起的，但我们仍能够将污水污泥燃烧的主要反应与各个参考化合物的燃烧联系起来。除了纤维素和木质素（分别占体重减轻的35％和20％）之外，还鉴定出了半纤维素，木聚糖，藻酸盐和方解石。纤维素的主要成分与最近的研究一致，该研究确定主要源自厕纸的纤维素是废水中的主要有机成分。