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Demand-oriented conversion of biogas is conducive to meeting the needs of biogas supply and reduces extra costs related to gas storage facilities. In this study, the effect of feeding regimes (FRs) on anaerobic digestion performance and microbial community structure of rice straw were investigated using continuously stirred tank reactors. The result showed that compared to the FRs of every day and every 6 days, the FR of every 3 days achieved the best biomethane yield and substrate conversion rate, which improved by 17.3% and 12.4%, respectively. Additionally, the FR of every 3 days had a significant impact on microbial richness and diversity, and also improved the abundance of dominant archaea Methanosaeta. This indicated that the FR of every 3 days was suitable for the growth rate of Methanosaeta, which resulted in better anaerobic digestion performance. A narrow FR is helpful to meet the demand-oriented conversion of biogas.

Opisthopappus taihangensis (Ling) Shih is a monotypic species (Anthemideae, Asteraceae) and an endemic endangered plant of China. In this study, we sequenced the complete chloroplast genome of O. taihangensis using Illumina HiSeq X Ten platform. The total length of O. taihangensis chloroplast genome is 151,089 bp, including a large single-copy region of length 82,877 bp, a small single-copy region of length 18304 bp, and a pair of 24,954-bp inverted repeat regions. The chloroplast genome of O. taihangensis has 132 genes, including 87 protein-coding, eight ribosomal RNA, and 37 transfer RNA genes. The overall GC content of the whole genome was 37.5%. The phylogenetic analysis revealed a close relationship between O. taihangensis and Chrysanthemum boreale.

Combined pretreatment using CaO and the liquid fraction of digestate (LFD) was proposed as an eco-friendly pretreatment method for high-quality anaerobic digestion (AD). In this study, rice straw was pretreated by CaO–LFD at three pretreatment temperatures (5, 20, and 35 °C) and four pretreatment times (1, 2, 3, and 4 days). The results showed that the optimum pretreatment condition for rice straw was 35 °C for 2 days. In this case, the maximum biomethane yield reached 308 mL g–1 of VS, 77.4% higher than that of the control. The Fitzhugh and Cone models were demonstrated to be more suitable for CaO–LFD pretreated rice straw in the AD process. AD of pretreated rice straw had a shorter effective biomethane production period and lag phase time, exhibiting high AD efficiency. This study enhances the knowledge about CaO–LFD pretreatment from multiple angles, in addition to demonstrating promising possibilities for practical application.

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