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Yang J, Tang S, Song B, Jiang Y, Zhu W, Zhou W, Yang G. Optimization of integrated anaerobic digestion and pyrolysis for biogas, biochar and bio-oil production from the perspective of energy flow. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 872:162154. [PMID: 36804988 DOI: 10.1016/j.scitotenv.2023.162154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/29/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Valorization of lignocellulosic biomass via anaerobic digestion (AD) is limited by its reluctant structure, leading to a substantial energy remaining in the solid digestate. To mitigate this effect, the integration of AD and pyrolysis has attracted attention in recent years. However, the energy recovery efficiency of this cascading system is still unclear, especially the time node. Herein, a comprehensive evaluation of this integration, using varied AD periods, was conducted, to produce biogas, bio-oil and biochar, and to enhance the energy recovery, from the perspective of energy flow. The result indicated that the accumulative CH4 yields increased from 33.23 to 249.20 mL/g VS as the AD time increased from 3 to 15 days. Pyrolysis of the obtained solid digestate obtained biochar from 28.81 to 35.96 %, while the bio-oil and pyrolysis gas slowly decreased. The highest energy efficiency of 71.9 % with a net energy gain of 2.0 MJ/kg wet biomass was achieved by the coupled system optimization at an AD time of 12 days as suggested by the energy flow analysis. This study provides new insight for the maximal conversion of biomass waste into energy products and provides a new way of recycling it.
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Affiliation(s)
- Juntao Yang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, CAS Key Laboratory of Renewable Energy, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255000, China
| | - Songbiao Tang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, CAS Key Laboratory of Renewable Energy, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; School of civil engineering, University of Science and Technology Liaoning, Anshan 114051, China
| | - Bing Song
- Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Private Bag 3020, Rotorua 3046, New Zealand
| | - Yujing Jiang
- State Key Laboratory of Pollution Control and Resource Reuse, State Key Laboratory of Analytical Chemistry for Life Science, the Frontiers Science Center for Critical Earth Material Cycling, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Wenlei Zhu
- State Key Laboratory of Pollution Control and Resource Reuse, State Key Laboratory of Analytical Chemistry for Life Science, the Frontiers Science Center for Critical Earth Material Cycling, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Weihong Zhou
- School of civil engineering, University of Science and Technology Liaoning, Anshan 114051, China
| | - Gaixiu Yang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, CAS Key Laboratory of Renewable Energy, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China.
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Enhanced Energy Recovery from Food Waste by Co-Production of Bioethanol and Biomethane Process. FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7040265] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The primary objective of this research is to study ways to increase the potential of energy production from food waste by co-production of bioethanol and biomethane. In the first step, the food waste was hydrolysed with an enzyme at different concentrations. By increasing the concentration of enzyme, the amount of reducing sugar produced increased, reaching a maximum amount of 0.49 g/g food waste. After 120 h of fermentation with Saccharomyces cerevisiae, nearly all reducing sugars in the hydrolysate were converted to ethanol, yielding 0.43–0.50 g ethanol/g reducing sugar, or 84.3–99.6% of theoretical yield. The solid residue from fermentation was subsequently subjected to anaerobic digestion, allowing the production of biomethane, which reached a maximum yield of 264.53 ± 2.3 mL/g VS. This results in a gross energy output of 9.57 GJ, which is considered a nearly 58% increase in total energy obtained, compared to ethanol production alone. This study shows that food waste is a raw material with high energy production potential that could be further developed into a promising energy source. Not only does this benefit energy production, but it also lowers the cost of food waste disposal, reduces greenhouse gas emissions, and is a sustainable energy production approach.
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Net Energy Analysis and Techno-Economic Assessment of Co-Production of Bioethanol and Biogas from Cellulosic Biomass. FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7040229] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Co-production is a process based on the biorefinery concept that maximizes the benefit of biomass by reusing residue from the production of one product to produce others. In this regard, biogas is one of the most researched second products for the production of ethanol from cellulosic biomass. However, operating this scheme requires additional investment in biogas processing equipment. This review compiles data from research studies on the co-production of bioethanol and biogas from lignocellulosic biomass to determine which is more worthwhile: leaving the residue or investing more to benefit from the second product. According to previous research, ethanol stillage can be converted to biogas via anaerobic digestion, increasing energy output by 2–3 fold. Techno-economic studies demonstrated that the co-production process reduces the minimum ethanol selling price to a level close to the market price of ethanol, implying the possibility of industrializing cellulosic ethanol production through this scheme.
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