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Paper wastes form the major biodegradable fraction of the municipal solid waste. One of the best ways to treat paper wastes is using them as a feedstock for biomethane production through anaerobic digestion (AD). However, the AD characteristics, kinetics, and energy potential of different types of paper wastes are not clear. In this study, four kinds of typical paper wastes including corrugated board (CB), office paper (OP), tissue paper (TP), and magazine paper (MP) were used as feedstocks to produce biomethane at different volatile solids (VS) organic loading (OL). TP had a high cellulose content and showed high biomethane potential, while the lowest was obtained by CB, possibly due to its high lignin content. Kinetic analysis showed that Cone and modified Gompertz model could fit the biomethane production process well. Energy potential analysis revealed that biomethane yield, electric generating efficiency, and electricity price were the principal factors accounting for the profitability of biomethane production project treating paper wastes. Overall, paper wastes could be a promising feedstock for biomethane production, because paper wastes not only had high biomethane yield and biodegradability that exceeded many kinds of organic wastes but also could be continuously supplied for AD plants without the influence of seasonal changes. • Anaerobic digestion characteristics of typical paper wastes were investigated. • High cellulose content in tissue paper might account for its high biomethane yield. • Corrugated board with high lignin content showed the lowest biomethane yield. • Energy potential of the anaerobic digestion of paper wastes was evaluated. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is the most abundant natural resource with high biomethane potential. However, complex structure of lignocellulosic biomass has hampered the efficient utilization of this bioresource. Previous studies have investigated the overall anaerobic digestion performance of lignocellulosic biomass, but the individual participation of each lignocellulosic component during anaerobic digestion remained unclear. Thus, this study investigated the methane production characteristics of cellulose, hemicellulose, lignin and their mixtures along with the microbial communities involved in anaerobic digestion. The results showed that the biomethane potential of cellulose was higher than that of hemicellulose; however, hemicellulose was hydrolysed more quickly than cellulose, while lignin was very difficult to be digested. The higher concentrations of acetic, n -butyric and n -valeric acids hydrolysed from the hemicellulose resulted in a lower pH and more severe inhibition on methane production than that of cellulose, and the methanogenesis gradually recovered after pH adjustment. The co-digestion of cellulose and hemicellulose increased the methane yield and biodegradability compared to mono-digestions. The addition of lignin to cellulose brought more significant decrease in the methane yield of cellulose than that of hemicellulose. Substrate-related bacteria such as Clostridium sensu stricto , Lutaonella , Cloacibacillus and Christensenella showed higher relative abundance in cellulose digestate, and sugar-fermenting bacteria such as Saccharofermentans , Petrimonas and Levilinea were more rich in the digestate of hemicellulose. Moreover, methanogenic Methanospirillum and Methanothrix likely contributed to the methane production of cellulose, while aciduric methanogens from Methanobrevibacter , Methanomassiliicoccus , Methanobacterium and Methanoculleus contributed to that of hemicellulose. This study provides a deeper understanding of the mechanism in the bioconversion of lignocellulosic biomass during anaerobic digestion. [ABSTRACT FROM AUTHOR]

A large amount of sheep dung (SD) produced on farms in China is a potential feedstock for production of clean energy in the form of biogas. Similarly, waste paper can be a notable energy source that is worth exploiting. In this study, we assessed the feasibility of co-digesting nitrogen-rich SD with the carbon-rich corrugated board (CB) or waste office paper (OP) in varying volatile solids (VS) ratios, to produce methane. Synergistic effect of co-digesting SD with CB and SD with OP on methane production was found in this study. The highest methane yields of 151.62 and 198.85 mL/g-VS were obtained during the co-digestions of SD with CB at 4:1 ratio (SDCB) and SD with OP at 2:3 ratio (SDOP), respectively. High-throughput 16 S rRNA gene sequencing demonstrated that the microbial diversity and richness in SDCB and SDOP co-digests were higher than in SD and OP mono-digests, respectively. Characteristic bacteria and archaea in the digests were strongly substrate-related and might contribute to methane production. The validated results indicated that methane production through anaerobic co-digestion of SD and waste paper can be an efficient way that could not only reduce environmental pollution but also contribute to methane production. [ABSTRACT FROM AUTHOR]

Highlights • Swine slaughterhouse waste produced a maximum methane yield of 999.2 mL/g VS. • Lipid hydrolysis led to serious accumulation of linoleic, oleic and palmitic acids. • Increase of palmitic acid produced by degradation of oleic acid was observed. • Predominant microorganisms were Clostridium , Syntrophomonas and Methanospirillum. Abstract This study investigated methane production, long-chain fatty acids (LCFAs) profile, and predominant microorganisms in anaerobic digestion (AD) of lipid-rich swine slaughterhouse waste (SSW). The maximum methane yield was 999.2 mL/g VS. LCFAs, as inhibitory hydrolysis products, accumulated first to 1165 mg/L on day 3, and then decreased sharply to 125.7 mg/L on day 9, and finally were degraded to 20 mg/L on day 27. Linoleic acid (C18:2), oleic acid (C18:1) and palmitic acid (C16:0) were the dominant LCFAs. The easy conversion of C18:1 to C16:0 compared with difficult degradation of C16:0 resulted in an increase of C16:0 on day 4–6. Predominant microorganisms were Clostridium , Syntrophomonas and Methanospirillum. This study proved the high methane potential of lipid-rich SSW and gained insights into the degradation process by analysis of intermediates of LCFAs and predominant microorganisms. The results can provide valuable guidance for efficient utilization of this waste to produce methane in future. [ABSTRACT FROM AUTHOR]

Alkaline pretreatment of lignocellulosic biomass has been intensively investigated but heavy water usage and environmental pollution from wastewater limits its industrial application. This study presents a pretreatment technique by in-situ injection of potassium hydroxide concentrations ranging from 0.8% to 10% (w/w) into the briquetting process of wheat straw and meadow grass. Results show that the biomethane yield and hydrolysis rate was improved significantly with a higher impact on wheat straw compared to meadow grass. The highest biomethane yield from wheat straw briquettes of 353 mL.g −1 VS was obtained with 6.27% (w/w) potassium hydroxide injection, which was 14% higher than from untreated wheat straw. The hydrolysis rates of wheat straw and meadow grass increased from 4.27 × 10 −2 to 5.32 × 10 −2 d −1 and 4.19 × 10 −2 to 6.00 × 10 −2 d −1 , respectively. The low water usage and no wastewater production make this a promising technology. [ABSTRACT FROM AUTHOR]

As an alternative class of antimicrobial agents, antimicrobial peptides (AMPs) have gained significant attention. In this study, K1K8, a scorpion AMP derivative, showed effective activity against Candida albicans including clinically resistant strains. K1K8 killed C. albicans cells mainly by damaging the cell membrane and inducing necrosis via an ROS-related pathway. K1K8 could also interact with DNA after damaging the nuclear envelope. Moreover, K1K8 inhibited hyphal development and biofilm formation of C. albicans in a dose-dependent manner. In the mouse skin infection model, K1K8 significantly decreased the counts of C. albicans cells in the infection area. Overall, K1K8 is a potential anti-infective agent against skin infections caused by C. albicans. [Display omitted] • K1K8 showed effective activity against Candida albicans in vitro. • K1K8 damaged the cell membrane, induced necrosis, and interacted with DNA. • K1K8 inhibited hyphal development and biofilm formation of C. albicans. • K1K8 effectively inhibited C. albicans in a mouse skin infection model. • K1K8 is a potential anti-infective agent against skin infections caused by C. albicans. [ABSTRACT FROM AUTHOR]

This study employs a microaerobic pretreatment that includes different microbial reagents combined with oxygen to enhance the energy conversion potential of rice straw (RS) via anaerobic digestion (AD) in a more cost-effective and time-efficient manner. Five broad varieties of microbial reagents including liquid consortium (LC), cow manure (CM), sheep dung (SD), biogas slurry (BS), and straw-decomposing consortia (SC), have been used as sources of useful microbes at varying oxygen concentrations of 0, 6, 12 and 24 mL O2 /gVS to explore the effect of microaerobic pretreatment on RS degradation. The results showed that RS pretreated with SC had the highest cumulative methane yield (CMY) of 311.7 mL/gVS at 12 mL O2 /gVS, followed by BS, CM, LC, and SD, with the CMYs of 270.5, 263.2, 257.1, and 256.7 mL/gVS at 6 mL O2 /gVS, respectively. The RS pretreated with SC, BS, CM, LC, and SD led to improvements in the methane yield by 88.7%, 63.7%, 59.3%, 55.6%, and 55.4%, respectively, compared to the untreated RS. The microbial community analysis revealed that the relative abundance (RA) of Firmicutes , which are known to play a key role in accelerating the rate of hydrolysis, increased after microbial pretreatment combined with oxygen supply. The RA of Clostridium III , which facilitates cell wall degradation via hydrolytic pathways along with other sugar-fermenting bacteria, such as Saccharofermentans , Lutaonella , and Sedimentibacter, increased after AD in the digestate of pretreated RS compared to that in untreated RS. Moreover, a shift in acetoclastic and hydrogenotrophic archaea, including Methanothrix and Methanospirillum, was also observed, indicating precursor changes resulted by pretreatments and varied microbial metabolism, which might have enhanced the methane production process of RS. The energy potential analysis revealed that microbial pretreatment was a suitable technique for stimulating the energy conversion efficiency of RS. This study can be used as a reference for future utilization of a diverse range of lignocellulosic materials for clean energy production. [Display omitted] • Microbial pretreatment combined with oxygen supply improved methane production of the rice straw. • Rice straw pretreated by straw decomposing consortia resulted in the improvement of methane yield by 88.7%. • Oxygen supply has enhanced the relative abundance of the functional bacteria facilitating rate of hydrolysis. • Methanothrix was the predominant archaeal genus in the straw-decomposing consortia pretreatment group. • Energy potential analysis confirmed that microbial pretreatment enhances energy output of rice straw. [ABSTRACT FROM AUTHOR]