Hydrothermal co-carbonization of sewage sludge and pinewood sawdust for nutrient-rich hydrochar production: Synergistic effects and products characterization

• Published in: Journal of environmental management Vol. 201; pp. 52 - 62
• Main Authors: Zhang, Xiaojuan, Zhang, Lei, Li, Aimin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2017
• Subjects: Biomass; Carbon; Different mixing ratio; Fourier transform infrared spectroscopy; hydrochars; Hydrothermal carbonization; mixing; Nitrogen; nuclear magnetic resonance spectroscopy; Nutrient elements; nutrients; Phosphorus; sawdust; scanning electron microscopy; Sewage; sewage sludge; Spectroscopy, Fourier Transform Infrared; Synergism; Different mixing ratio; Nutrient elements; Biomass; Hydrothermal carbonization; Synergism
• ISSN: 0301-4797; 1095-8630; 1095-8630
• DOI: 10.1016/j.jenvman.2017.06.018

The aim of this study is to explore the synergistic effects of hydrothermal co-carbonization of sewage sludge and pinewood sawdust on hydrochar production. Firstly, the effects of mixing ratios on hydrothermal carbonization were investigated, and then, the hydrochar was characterized by diverse analytical techniques. The mass balance results indicated that a significant synergistic enhancement occurred in terms of the increased hydrochar yield, organic and carbon retentions. By combining sewage sludge and pinewood sawdust at the mass ratio of 1:1, 58.11 ± 0.91% of hydrochar yield was obtained with high synergistic coefficients (8.41% for hydrochar yield, 13.09% for carbon retention, and 14.92% for organics retention). The hydrochar properties of nutrients, such as nitrogen and phosphorus, and surface functional groups were improved by hydrothermal co-carbonization approach. The FT-IR spectra, CP-MAS 13C NMR and SEM results further indicated that hydrothermal co-carbonization promoted the development of aromaticity and surface structure. Our findings suggested that hydrothermal co-carbonization is a promising strategy to tailor high-performance hydrochar for different applications. •The mixing ratios of 1:1 showed the better performance in terms of solid yield, carbon and organics retention.•The nitrogen fractions in the solid were increased.•The hydrothermal co-carbonization increased the amount of the surface functional group density of hydrochar by synergism.