Identifying the fate of nitrogenous species during sewage sludge pyrolysis via in-situ tracing of protein-sludge inherent components interactions

Zhihang Yuan; Wenchao Ma; Nanwen Zhu; Ying Zhu; Shaolin Wu; Ziyang Lou

doi:10.1016/j.scitotenv.2022.160437

Identifying the fate of nitrogenous species during sewage sludge pyrolysis via in-situ tracing of protein-sludge inherent components interactions

Sci Total Environ. 2023 Feb 10;859(Pt 2):160437. doi: 10.1016/j.scitotenv.2022.160437. Epub 2022 Nov 23.

Authors

Zhihang Yuan¹, Wenchao Ma², Nanwen Zhu¹, Ying Zhu³, Shaolin Wu⁴, Ziyang Lou⁵

Affiliations

¹ Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
² School of Environmental Science and Engineering, Tianjin Key Lab of Biomass/Wastes Utilization, Tianjin University, Tianjin 300072, China.
³ Advanced Materials Institute, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250014, China.
⁴ Shanghai Solid Waste Management Center, Shanghai 200235, China.
⁵ Shanghai Engineering Research Center of Solid Waste Treatment and Resource Recovery, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China; China Institute for Urban Governance, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: louworld12@sjtu.edu.cn.

PMID: 36427709
DOI: 10.1016/j.scitotenv.2022.160437

Abstract

The effect of interactions between different components in sewage sludge on the thermochemical transformation of nitrogenous species is usually neglected, which is important to explain the generation mechanism of some key nitrogenous by-products. Here, we investigated the distribution, form, and chemical properties of the products from sludge-extracted protein (PR) under different pyrolysis scenarios using several in-situ probe techniques, to elucidate the critical role of typical sludge organics/inorganics on the evolution of nitrogenous intermediates and by-products. The results suggested that Ca/Fe/Si/Al-containing inorganics significantly affected the pyrolytic behavior of PR and the thermal transformation of nitrogenous species, while sludge organics, including humic acids and polysaccharides, had limited effects on the temperature-dependent evolution of nitrogenous species in PR. Among them, calcium oxide catalyzed the ring-opening reaction of heterocyclic-N with aromatic-like structures, resulting in a 21.1 %-68.8 % reduction in nitrogen fixation efficiency in the char. At lower temperatures (350-450 °C), calcium oxide caused more nitrogen to be transferred to the gas/tar phases in the form of NH₃ and heterocyclic-N, and it also enhanced the conversion of nitrile-N → HCN → NO at temperatures above 450 °C. In contrast, polyferric salts inhibited the devolatilization of mono-heterocyclic-N and enhanced the thermal stability of poly-heterocyclic-N, resulting in a maximum increase of 18.5 mg·g^-1 of nitrogen content in the char, while reducing the release of NH₃ and HCN by 71.1 % and 32.0 %. This work elucidated the interaction between PR and inherent components in sludge, providing key information for the control of nitrogenous volatiles and NO_x.

Keywords: Heterocyclic-N; Nitrogenous species; Pyrolysis; Sewage sludge; Thermal transformation route.

MeSH terms

Nitrogen* / analysis
Oxides
Pyrolysis
Sewage* / chemistry

Substances

Sewage
Nitrogen
lime
Oxides