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The production of biogas from lignocellulose by anaerobic digestion (AD) has attracted much attention recently. However, the over-acidification phenomenon and low biogas yield often occur during the AD of lignocellulose. In this work, the liquid-state fermentation mode using pretreatment liquor from dilute acid treated rice straw without detoxification for continuous biogas production in a 100 L internal circulation reactor was studied. The highest biogas yield reached 0.66 m3/kg CODconsumption while the methane yield was 0.38 m3/kg CODconsumption. The pH values of outlet were maintained at 6.9–7.4, and even the inlet pH values were lower than 6.0. Furthermore, from the second day to the end of fermentation, the COD removal rates were more than 90%, even though the inlet COD was close to 20000 mg/L. The organic substances from acid pretreated rice straw were efficiently degraded by AD, which was confirmed by substrate metabolism analysis. These results indicated that the whole fermentation process of AD was very stable and showed great potential for industrial application. [Display omitted] • AD of pretreatment liquor from dilute acid treated rice straw without detoxification. • The COD removal rate during the AD process was more than 85%. • The sugars and organic acids could be utilized efficiently. • Continuous biogas production in a 100 L IC reactor was investigated. [ABSTRACT FROM AUTHOR]

Biogas is one of the important renewable energy sources, which is expected to significantly contribute not only for the successful achievement of a low carbon transition but also to achieve global climate change policy targets. Private investment is identified as a critical factor for biogas sector to fulfill its expected role. Hence, this paper emphasizes on identifying private stakeholder’s investment criteria in order to increase its active involvement for biogas in China. This study focused on banks, insurance companies, pension funds, private equity funds and high network individuals as the primary stakeholders. It applies an SWOT-AHP-TOWS analysis, in which the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of stakeholders are identified and then prioritized by using the analytical hierarchy process (AHP). Finally, the TOWS matrix supports the development of private investment strategies, which serve as a foundation for Chinese policy makers to promote private investments in the biogas sector. The following strategies have been identified as the most important ones: (1) Promoting financial tailored biogas products in terms of volume, interest rate and duration for banks; (2) Permitting insurance companies and pension funds directly investing into biogas equity; (3) Encouraging public-private partnerships and (4) Improving project cooperation by introducing professional guidance. [ABSTRACT FROM AUTHOR]