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[Display omitted] • Effects of various microaerobic pretreatments on AD of tobacco straw were studied. • Biogas slurry as pretreatment agent dosing 4 mL/g VS of O 2 (BS-4) performed better. • BS-4 had a good performance in the lignocellulosic decomposition of tobacco straw. • O 2 dosing in microbial pretreatment process could change the microbial diversity. Tobacco straw is an abundant biomass in China's agricultural ecosystems, and has high potential for methane production. However, the anaerobic digestion (AD) efficiency is limited by the recalcitrant lignocellulose structure of the tobacco straw. In this study, three microaerobic pretreatments were performed for the AD of tobacco straw to increase methane production. Among them, microbial pretreatment with biogas slurry at an oxygen concentration of 4 mL/g VS resulted in the highest methane production of 349.1 mL/g VS, increasing by 19.8 % than that of untreated. During this pretreatment, the relative abundances of Enterococcus and Clostridium sensu stricto 12 , which are closely related to acetic acid production and cellulose degradation, were high, and these bacteria might have an important contribution to substrate hydrolysis and the methanogenesis efficiency of the AD process. This study advances the understanding of microaerobic pretreatment processes and provides technological guidance for the efficient utilization of tobacco straw. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anaerobic digestion performance of common textile wastes was investigated. • The CMPs of textile wastes ranged from 159.9 to 356.0 mL/g VS. • Flax possessed the highest CMP and B D of 356.0 mL/g VS and 78.0 %, respectively. • Morphological and micro-structural changes of textile wastes during AD were recorded. • Clostridium sensu stricto and Methanothrix cooperated closely in AD process. The dramatic increase of textile wastes has become a major global concern, which calls for alternative practices to alleviate severe environmental pollution and waste of resources due to their improper disposal and management. Anaerobic digestion (AD) is a cost-effective and eco-friendly technology that allows the bioconversion of organic wastes into clean energy (methane), which might be potentially useful for recycling textile wastes. In this study, AD was applied to 11 commonly available textile wastes in daily life to explore their feasibility, along with the methane production efficiency, biodegradability (B D), degradation mechanism, and microbial community dynamics during AD. The results showed that all textile wastes presented an obvious decomposition from an integrated shape to fragmented pieces within 18 days except blue denim. The highest experimental methane production (EMP) of 356.0 mL/g volatile solids (VS) and B D of 78.0 % were obtained with flax. The degradation mechanism could be concluded that predominant bacteria, especially Clostridium sensu stricto , first attached to the surface of textile waste and converted its main compositions cellulose and hemicellulose into acetate as the core intermediate. Then, acetate was utilized by the major methanogen, Methanothrix , through the acetoclastic methanogenesis pathway to produce methane. This study not only enriches the understanding of textile wastes degradation mechanisms during AD and provides very useful data on methane production from commonly available textile wastes but also proposes a promising method for efficiently recycling and utilizing the diverse range of textile wastes to reduce waste pollution and generate clean energy simultaneously. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of loaded O 2 in microbial pretreatment on anaerobic digestion were studied. • Higher yield of volatile fatty acids after microaerobic pretreatment was detected. • Anaerobic pretreatment by straw composting inoculant had the highest methane yield. • Microbial responses to O 2 loading varied significantly with microbial consortium. Microbial pretreatment to lignocellulosic biomass for anaerobic digestion (AD) has achieved increased attention; however, the low efficiency and unclear mechanism of oxygen parameter affecting this process performance limit its practical application. In this study, five readily available microbial consortia were developed to analyze the influences of various oxygen concentrations during pretreatment process upon methane conversion efficiency and microbiota within AD of giant grass. Results found that anaerobic pretreatment by liquid or straw composting inoculant, along with microaerobic pretreatment by cow manure at 10 mL/g VS oxygen concentration, obtained 23.1%, 24.4%, and 16.0% higher methane yields (275.3, 279.8, and 265.3 mL/g VS) than corresponding untreated group, respectively. Microbial community analyses showed that microbial responses to oxygen varied significantly with microbial consortium, which consequently caused different AD performances. The findings will enrich theoretical knowledge of microbial pretreatment and provide a technological guidance for efficient utilization of giant grass and other lignocellulosic biomasses. [ABSTRACT FROM AUTHOR]