Effect of electromagnetic induction drying on the drying-incineration process of dyeing sludge: focus on migration and conversion of sulfur

Mengxin Lu; Yongjie Xue; Hui Zhao; Xiaoshan Zhang; Teng Wang

doi:10.1016/j.wasman.2023.10.003

Effect of electromagnetic induction drying on the drying-incineration process of dyeing sludge: focus on migration and conversion of sulfur

Waste Manag. 2023 Oct 6:171:522-531. doi: 10.1016/j.wasman.2023.10.003. Online ahead of print.

Authors

Mengxin Lu¹, Yongjie Xue¹, Hui Zhao¹, Xiaoshan Zhang¹, Teng Wang²

Affiliations

¹ State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.
² School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China. Electronic address: 2018001@wtu.edu.cn.

PMID: 37806160
DOI: 10.1016/j.wasman.2023.10.003

Abstract

Secondary sulfur pollution in dyeing sludge (DS) during drying and incineration is a major environmental problem necessitating in-situ control. To robustly immobilise sulfur during drying-incineration, the authors introduce an electromagnetic induction (EMI) drying method and reveal the corresponding migration and conversion of sulfur in DS. The EMI-drying efficiency reached 10.69%/min, five times that of thermal drying. EMI drying increases the relative sulfoxide ratio from that of thermal drying. In a sludge-sulfur model, the proposed treatment promoted the oxidation and decomposition of organic sulfur without noticeably affecting the inorganic sulfur. The selective oxidation process during EMI drying promotes sulfur stabilisation in dried DS, decreasing the performance and stability of DS combustion. The sulfur-containing pollutants released during the incineration of DS mainly contain H₂S, followed by CH₃SH and SO₂. EMI drying increases the outputs of SO₂ and CH₃SH but decreases the outputs H₂S and total sulfur compared with the outputs of thermal drying. Under the sulfur-model conditions, EMI promoted the conversion of inorganic sulfur to sulfur-containing gases (especially H₂S) during incineration. In contrast, the sulfur stabilised by partial oxidation of organic sulfur in the EMI-dried DS was not easily converted to gaseous sulfur during subsequent combustion. Overall, EMI inhibits the release of sulfur during the combined drying-incineration process of DS.

Keywords: Dry-incineration; Dyeing sludge; Electromagnetic induction; Sulfur.