A new environment-friendly polyferric sulfate-catalyzed ozonation process for sludge conditioning to achieve deep dewatering and simultaneous detoxification

• Published in: Journal of cleaner production 2022-07, Vol.359, p.132049, Article 132049
• Main Authors: Ge, Dongdong, Huang, Shouqiang, Cheng, Jiehong, Han, Ying, Wang, Yuhui, Dong, Yanting, Hu, Jinwen, Li, Guobiao, Yuan, Haiping, Zhu, Nanwen
• Format: Article
• Language: English
• Subjects: Detoxification; ESI FT-ICR MS; Ozonation; Reactive oxygen species; Sludge dewatering
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2022.132049

The dewaterability of sludge from biological sewage treatment plants is extremely poor since the highly hydrophilic biomacromolecules. This work developed a new polyferric sulfate-catalyzed ozonation (PFS/O3) process to disintegrate sludge flocks and extracellular hydrophilic substrates for liberating bound water. With 40 mg/gTS PFS catalyzing 60 mg/gTS O3, bound water content declined to 1.42 g/gTS, and water content of dewatered sludge dropped to 59.79%. Meanwhile, microbial cells were inactivated by 47.3%, and extracellular protein-like components were degraded substantially, rendering the neutral potential and low apparent viscosity. PFS/O3 treatment significant facilitated CHO-compound decomposition, reactions of nitrogenous groups, and P-containing biomolecule release. And more hydrophobic groups were exposed on the bio-matrix surface. Besides, polyhydroxy Fe as skeleton builder reconstructed sludge drainage passages for more water permeation. The predominant mechanism for enhancing sludge dewaterability in PFS/O3 process was the oxidation role of improved •OH, and the chemical reaction chains were proposed tentatively. Moreover, this process simultaneously removed 26.95%–60.05% heavy metals and 31.18%–80.91% polycyclic aromatic hydrocarbons in dewatered sludge, and its chemical cost was preliminarily estimated as 88.80 USD$/tonTS. Therefore, the PFS/O3 process was of great prospect and practical value in sludge treatment for dewatering and detoxification. [Display omitted] •A new PFS-catalyzed O3 process assisted sludge deep dewatering and detoxification.•EPS conformation turned to be loosened with more hydrophobic groups exposed.•Molecular composition and transformation of DOM were shown by ESI FT-ICR MS.•Chemical reaction mechanism of PFS-catalyzed O3 was put forward for the first time.•Polyhydroxy Fe serving as supporting skeleton rebuilt multihole drainage passages.