University of Coimbra, CIEPQPF, Department of Chemical Engineering, Rua Sílvio Lima, Pólo II, Pinhal de Marrocos, 3030-790, Coimbra, Portugal.
University of Coimbra, CIEPQPF, Department of Chemical Engineering, Rua Sílvio Lima, Pólo II, Pinhal de Marrocos, 3030-790, Coimbra, Portugal.
J Environ Manage. 2021 Oct 15;296:113255. doi: 10.1016/j.jenvman.2021.113255. Epub 2021 Jul 16.
Sewage sludge (SS) is a global environmental, social, and economic problem that requires a sustainable management approach. Still, the production of other industrial wastes, such as lime mud (LM), has recently gained considerable attention to avoid landfilling. This work aims to present a new approach for converting SS and LM into value-added products within the circular economy perspective. In particular, the effect of LM and calcined lime mud (CLM) as drying adjuvants and SS sanitation agents are investigated. Two out of three SS samples show Escherichia coli contamination above the Portuguese limit established for soil application, while no Salmonella spp. was detected in the searched samples. The addition of CLM to SS in a ratio between 0.05 and 0.15 g CLM/g, lead to complete elimination of the microbiological contamination in almost all cases. Contrarily, the use of LM does not seem efficient to act as a sanitation agent. Both LM and CLM show a positive impact on the drying process when compared to the raw SS, increasing the drying rate, and reducing the drying time. The most favourable drying conditions to maximize the drying rate and minimize the drying time (until 30% of moisture) are 130 °C, 0.15 g adj/g, and 2.5 mm of plate thickness. The thermal treatment (100 and 130 °C) without adjuvants reduces the microbiological contamination below the legal limit. Overall, a beneficial effect is observed by adding CLM to SS, open the possibility of producing a safer organic soil improver.
污水污泥（SS）是一个全球性的环境、社会和经济问题，需要采取可持续的管理方法。然而，最近石灰泥（LM）等其他工业废物的产生引起了相当大的关注，以避免填埋。本工作旨在提出一种将 SS 和 LM 转化为循环经济视角下附加值产品的新方法。特别是，研究了 LM 和煅烧石灰泥（CLM）作为干燥助剂和 SS 卫生剂的效果。三个 SS 样品中的两个显示出大肠杆菌污染超过葡萄牙规定的土壤应用限量，而在搜索的样品中未检测到沙门氏菌属。将 CLM 以 0.05 至 0.15 g CLM/g 的比例添加到 SS 中，几乎在所有情况下都导致微生物污染完全消除。相反，LM 似乎不能有效地作为卫生剂。与原始 SS 相比，LM 和 CLM 均对干燥过程产生积极影响，提高了干燥速率并缩短了干燥时间。为了最大程度地提高干燥速率并最小化干燥时间（直至 30%的水分），最有利的干燥条件是 130°C、0.15 g 助剂/g 和 2.5mm 的板厚。在没有助剂的情况下，热处理（100 和 130°C）将微生物污染降低到法定限量以下。总的来说，向 SS 添加 CLM 会产生有益的效果，为生产更安全的有机土壤改良剂开辟了可能性。
