Integrating hydrothermal carbonization and chemical leaching to recover biogenic carbon from sewage sludge.

IF 8 2区 环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES
Journal of Environmental Management Pub Date : 2025-01-01 Epub Date: 2024-12-15 DOI:10.1016/j.jenvman.2024.123516
A Salimbeni, H Demey
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引用次数: 0

Abstract

With more than 10 million dry tons annually produced in the EU and a carbon content of approximately 30% db, sewage sludge (SS) can be a strategic source of biogenic carbon. However, the high moisture content and large amount of ash are strong barriers to sustainable valorisation. This study aims to assess the potential of hydrothermal carbonisation (HTC) as a sustainable alternative to sludge drying. Furthermore, it aims to test the integration of HTC and chemical leaching to convert sewage sludge into a leached hydrochar (LHC) useable as an alternative to fossil coal in steelmaking, and to extract inorganic compounds. Seven HTC tests were conducted at temperatures ranging from 180 to 270 °C and a residence time of 20 and 120 min. Hydrochar was chemically leached with HNO3 at 70 °C for 1 h. On average, a solid mass yield of 62% was obtained by the HTC tests; the residence time didn't significantly affect the process performance and the hydrochar composition. In all tests, a significant portion of sludge carbon (between 25% and 38.5%) was found as TOC in the aqueous phase. After leaching, the ash content in the LHC was reduced by half. Extraction efficiencies of >95% for P and Ca and >80% for Fe were achieved. The LHC was more stable than raw hydrochar when subjected to gasification with CO2 above 800 °C. Moreover, LHC showed potential as reducing agent in blast furnaces, with an average replacement ratio of 40%.

水热炭化与化学浸出相结合,从污泥中回收生物炭。
欧盟每年生产超过1000万吨干污泥,含碳量约为30% db,污水污泥(SS)可以成为生物碳的战略来源。然而,高含水率和大量灰分是可持续增值的强大障碍。本研究旨在评估热液碳化(HTC)作为污泥干燥的可持续替代方案的潜力。此外,它旨在测试HTC和化学浸出的整合,将污水污泥转化为浸出的碳氢化合物(LHC),可作为炼钢中化石煤的替代品,并提取无机化合物。在温度为180 ~ 270℃,停留时间为20 ~ 120 min的条件下,进行了7次HTC试验。在70℃条件下,HNO3对烃类进行化学浸出,浸出时间为1 h。HTC试验的平均固体质量产率为62%;停留时间对工艺性能和烃类组成影响不显著。在所有的测试中,在水相中发现了相当一部分污泥碳(在25%到38.5%之间)作为TOC。浸出后,LHC中的灰分含量降低了一半。>对磷、钙的萃取效率为95%,>对铁的萃取效率为80%。在800℃以上的CO2气化条件下,LHC比原料煤更稳定。此外,LHC在高炉中表现出作为还原剂的潜力,平均替代率为40%。
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来源期刊
Journal of Environmental Management
Journal of Environmental Management 环境科学-环境科学
CiteScore
13.70
自引率
5.70%
发文量
2477
审稿时长
84 days
期刊介绍: The Journal of Environmental Management is a journal for the publication of peer reviewed, original research for all aspects of management and the managed use of the environment, both natural and man-made.Critical review articles are also welcome; submission of these is strongly encouraged.
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