Liquefaction of sewage sludge in ethanol-water mixed solvents for bio-oil and biochar products

Fa-ying Lai, Yan-chao Chang, Hua-jun Huang, Guo-qiang Wu, Jiang-bo Xiong, Zi-qian Pan and Chun-fei Zhou

Energy, 2018, vol. 148, issue C, 629-641

Abstract: Liquefaction of sewage sludge (SS) is a promising technology for the preparation of bio-oil (target product) and biochar (by-product). The liquefaction of SS in ethanol-water cosolvent were preliminarily investigated in this study. There existed synergetic effects between ethanol and water on the liquefaction of SS. Higher bio-oil yield (33.5–36.1 wt%) were obtained in ethanol-water cosolvent, compared to those in pure water (32.2 wt%) and pure ethanol (26.8 wt%). Furthermore, the bio-oil obtained in ethanol-water cosolvent contained higher content of ester components, suggesting higher bio-oil quality. The addition of Na2CO3 further increased the yield of bio-oil (37.5 wt% versus 34.9 wt%), but lowered the quality of bio-oil. The main two types of coke oils in bio-oils were diesel oils and lubricating oils. Elemental, proximate and micromorphology analyses of biochars further indicated that ethanol-water cosolvent had better degradation/transformation effects on SS. The biochars obtained from the liquefaction of SS in ethanol-water cosolvent possessed similar specific surface area (23.0–26.0 m2/g) and pore volume (0.118–0.141 cm3/g) to SS pyrolysis biochar. In view of the yield and quality of liquefaction products, ethanol-water cosolvent may be more proper for the liquefaction of SS, compared to pure water/ethanol.

Keywords: Sewage sludge; Liquefaction; Ethanol-water; Bio-oil; Biochar (search for similar items in EconPapers)
Date: 2018
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Citations: View citations in EconPapers (14)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:148:y:2018:i:c:p:629-641

DOI: 10.1016/j.energy.2018.01.186

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