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Graphical abstract Highlights • Cow manure (1/3) functioned as a stimulant during oat straw anaerobic digestion. • Addition of cow manure affected methane yield more than the total solids content. • C/N ratio = 27 was suitable for anaerobic digestion of oat straw waste and cow manure. • Higher methane yields were due to the increasing degradation of cellulose. • Clustering analysis provided significant guidance for demonstrating project process. Abstract Impacts of adding different amounts of cow manure (CM) on the anaerobic digestion (AD) of oat straw (OS) with total solids content (TS) values of 4%, 6%, 8% and 10% was assessed over 50 days using batch experiments. A modified Gompertz model was introduced to predict the methane yield and determine the kinetic parameters. The optimum addition was a 1:2 ratio of CM to the OS added, which resulted in a suitable C/N ratio of 27 and a higher degradation rate of lignocellulose. The best cumulative methane yield of 841.77 mL/g volatile solids added (VS added) was 26.64% greater than that of digesting OS alone. In addition, the amount of CM added produced larger effects than that of changes in the TS. However, higher CM concentrations were found to be inhibitory. Clustering analysis could provide significant guidance for demonstrating project process and combining farming and animal husbandry. [ABSTRACT FROM AUTHOR]

Silage efficiency is crucial for corn stalk storage in methane production. This study investigated characteristics of dynamic changes in materials and microbes during the silage process of corn stalks from the initial to stable state. We conducted laboratory-scale study of different silage corn stalks, and optimized silage time (0, 2, 5, 10, 20, and 30 days) for methane production and the endogenous microbial community. The volatile fatty acid concentration increased to 3.00 g/L on Day 10 from 0.42 g/L on Day 0, and the pH remained below 4.20 from 5.80. The lactic acid concentration (44%) on Day 10 lowered the pH and inhibited the methane yield, which gradually decreased from 229 mL/g TS at the initial state (Day 0, 2) to 207 mL/g TS at the stable state (Day 10, 20, 30). Methanosaeta was the predominant archaea in both fresh and silage stalks; however, richness decreased from 14.11% to 4.75%. [ABSTRACT FROM AUTHOR]

A novel monomer who combined cross linker and functional groups together called 2,2'-(hexane-1,6-diyl)bis(2-methyl-2,3,3a,4,7,7a-hexahydro-1H-4,7-methanoisoindol-2-ium) iodide (HDHM-iodide) was synthesized and polymerized by Ring-opening Metathesis Polymerization (ROMP) to give a series of anion exchange membranes. The resulting monomers and polymers were characterized by 1 H and 13 C NMR, TGA. Directly cast from the polymerization solution on flat glass to form the clear, flexible anion exchange membrane. Swelling ratio and water uptake are only 6.2% and 28.04% at 60 °C for membrane with 2.32 mmol·g −1 ion exchange capacity (IEC). The conductivity of Poly (HDHM-Norbornene-hydroxide-12) and Poly(HDHM-Norbornene-chlorine-12) AEMs at room temperature up to 27 mS·cm −1 and 14 mS·cm −1 separately, and increased with temperature quickly. After 16 days immersed in 2 M NaOH solution, conductivity and IEC dropped at 60 °C in alkaline solution, 50% and 35% separately. The energy barrier of degradation pathways calculation reveled that Hofmann Elimination case 2 degradation pathway with the lowest energy barrier 12.181 kcal·mol −1 is most likely occurred when faced with hydroxide. Also, the energy barrier of Hofmann Elimination is lower than Nucleophilic Substitution degradation mechanism. [ABSTRACT FROM AUTHOR]

• Mn:CsPbBr 3 perovskite nanocrystals (NCs) revealed high green-emission at 520 nm under 365 nm excitation. • The photoluminescence quantum yields increased from 62.4 to 82.9% after Mn doping. • The luminescence of Mn2+ ions was observed by benzoyl chloride reprocessing adjusting band gap. CsPbBr 3 :Mn NCs were synthesized via a hot injection method to test the anion exchange reaction using ZnCl 2 and benzoyl chloride. In the case of no ion exchange reaction, Mn-doping resulted in the photoluminescence (PL) efficiency of the NCs increased from 62.4 to 82.9% and the stability greatly improved even though no Mn emission was observed. The NCs maintained the initial cubic phase structure. Interestingly, the ion exchange reaction using benzoyl chloride resulted in the host excitation to Mn2+ d-d transition. Bright Mn ion orange-emission was observed. The mild ion exchange reaction of benzoyl chloride greatly improved the stability of the NCs compared with ZnCl 2. To use the bright Mn ion emission, a white light-emitting diodes (LED) with a color coordinates of (0.320, 0.319) and color temperature of 5706 K was created using CsPbBr 3 :Mn NCs. The result provides an effective route to obtain high-performance white LED materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The objective of the present study is to assess the effect of the total solids (TS) content on the digestion performance, methanogenic pathways, and economic evaluation of anaerobic co-digestion with dairy manure and maize stover. The results showed that the cumulative methane yields decreased with increasing TS content, which was consistent with the maximum methane production rate and hydrolysis rate. The pH, alkalinity, soluble chemical oxygen demand, ammonium nitrogen, and volatile fatty acid content increased with increasing TS content. Analysis of the microbial community showed that the abundance of Methanosaeta decreased and Methanosarcina increased with increasing TS content, which led to the succession of the methanogenesis pathway from the acetoclastic pathway to the mixotrophic and hydrogenotrophic pathways. Results of the economic analysis indicated that the profitability of AD system increased with increasing TS content, resulting in more solid digestate being produced under the analysis conditions. [Display omitted] • TS content influences methane yield and volumetric methane productivity. • The succession from Methanosaeta to Methanosarcina with increasing TS content. • Increasing the TS content increases the net present value of anaerobic co-digestion. • The solid digestate determines the net present value of anaerobic co-digestion. • 14% TS is recommended for co-digestion with dairy manure and maize straw. [ABSTRACT FROM AUTHOR]

• Automated image-based method to observe microbubbles at high densities developed. • Error between manual and automated bubble size determination < 2%. • Small shifts of bubble size distribution and rise velocity can be detected. • Fast data processing allows continuous measurements. • Side stream sampling provides scope for in-situ microbubble measurements. Using microbubbles has gained significant interest in many domestic and industrial applications due to bubble stability in solution and increased mass transfer area. The characterisation of microbubble populations is therefore important and aids in the understanding of their behaviour. Microbubble characterisation remains challenging, particularly at high bubble densities. We have developed an in situ and automated method, based on image analysis, to determine bubble size distributions and bubble rise velocity at bubble densities of up to approximately 7 bubbles mm−2. The method uses image analysis of a side-stream viewing slit and was tested using air bubbles in water at diameters between 20 and 150 µm under a range of different conditions. The developed system enables fast, simple and accurate size determination for microbubbles, including continuous sampling and observation. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg2+) is one of the most toxic heavy metal ions which will cause permanent damage to the brain and kidneys. So, it is important to develop a sensitive, simple and reliable approach to detect Hg2+. In this work, we report a surface-enhanced Raman scatting (SERS) sensor by decorating the inner wall of capillary with 4,4′-dipyridyl (Dpy) functionalized silver nanoparticles (AgNPs). The main advantage of this sensor is that it can collect samples directly by capillary force and carry out on-site analysis by combining portable Raman spectrometer. In the presence of Hg2+, the Dpy molecules would be separated from the surface of AgNPs and coordinated with Hg2+, resulting in a decrease in the SERS signal. A linear correlation of Raman intensity with Hg2+ concentrations from 1 to 100 part-per-billion (ppb) was obtained for quantitative analysis and the limit of detection (LOD) was determined to be 0.1 ppb. The good reproducibility and selectivity of the sensor were also demonstrated. In addition, the sensors were successfully applied to detect Hg2+ in real environmental water samples, and the sampling process provided operation convenience compared to conventional methods. These results indicated that these capillary sensors had great potential for Hg2+ detection in practical use. Unlabelled Image • A SERS-based capillary sensor for the detection of Hg2+ was prepared. • The good reproducibility and selectivity of the sensor were demonstrated. • A linear correlation of Raman intensity with Hg2+ concentrations was obtained. • The quantitative results were applied to the detection of Hg2+ in environmental water. [ABSTRACT FROM AUTHOR]

The addition of trace elements to aid anaerobic digestion has already been widely studied. However, the effects of rare trace elements on anaerobic digestion remain unclear. In this study, the effects of Mo, Se and Mn on anaerobic digestion of rice straw were explored. The results showed the methane yield increased by 59.3%, 47.1% and 48.9% in the first 10 days following addition of Mo (0.01 mg/L), Se (0.1 mg/L) and Mn (1.0 mg/L), respectively. Toxic effects and the accumulation of volatile fatty acids (VFAs) were observed when the Se, Mo and Mn concentrations were greater than 100, 1000 and 1000 mg/L, respectively. The half-maximal inhibitory concentrations (IC 50 ) for Se, Mn and Mo were 79.9 mg/L, 773.9 mg/L and 792.3 mg/L, respectively. The addition of trace elements has changed the bacterial structure of the bacteria, which in turn has affected the digestion performance. [ABSTRACT FROM AUTHOR]

Trace elements were commonly used as additives to facilitate anaerobic digestion. However, their addition is often blind because of the complexity of reaction conditions, which has impeded their widespread application. Therefore, this study was conducted to evaluate deficiencies in trace elements during anaerobic digestion by establishing relationships between changes in trace element bioavailability (the degree to which elements are available for interaction with biological systems) and digestion performance. To accomplish this, two batch experiments were conducted. In the first, sequential extraction was used to detect changes in trace element fractions and then to evaluate trace element bioavailability in the whole digestion cycle. In the second batch experiment, trace elements (Co, Fe, Cu, Zn, Mn, Mo and Se) were added to the reaction system at three concentrations (low, medium and high) and their effects were monitored. The results showed that sequential extraction was a suitable method for assessment of the bioavailability of trace elements (appropriate coefficient of variation and recovery rate). The results revealed that Se had the highest (44.2%–70.9%) bioavailability, while Fe had the lowest (1.7%–3.0%). A lack of trace elements was not directly related to their absolute bioavailability, but was instead associated with changes in their bioavailability throughout the digestion cycle. Trace elements were insufficient when their bioavailability was steady or increased over the digestion cycle. These results indicate that changes in trace element bioavailability during the digestion cycle can be used to predict their deficiency. [ABSTRACT FROM AUTHOR]

Fe is widely used as an additive in anaerobic digestion, but its bioavailability and the mechanism by which it enhances digestion are unclear. In this study, sequential extraction was used to measure Fe bioavailability, while biochemical parameters, kinetics model and Q-PCR (fluorescence quantitative PCR) were used to explore its mechanism of stimulation. The results showed that sequential extraction is a suitable method to assess the anaerobic system bioavailability of Fe, which is low and fluctuates to a limited extent (1.7 to –3.1 wt%), indicating that it would be easy for Fe levels to be insufficient. Methane yield increased when the added Fe 2+ was 10–500 mg/L. Appropriate amounts of Fe 2+ accelerated the decomposition of rice straw and facilitated methanogen metabolism, thereby improving reactor performance. The modified Gompertz model better fitted the results than the first-order kinetic model. Feasibility analysis showed that addition of Fe 2+ at ≤50 mg/L was suitable. [ABSTRACT FROM AUTHOR]

Transglutaminase (TGase) is commonly used in plant protein modification to improve the quality of meat analogues. Pea protein, cornmeal, and wheat gluten were chosen for the preparation of pea protein-cornmeal-wheat gluten-meat analogue (PCWMA) due to their widespread availability and affordable price, while PCWMA fibrous structure differed slightly from that of real meat. Results showed that the addition of TGase enhanced the covalent cross-linking of protein, and also hardness and fibrous degree of extrudates were significantly improved. However, it was detrimental to the formation of fibrous structure when the amount of TGase addition exceeded 0.3%. Protein rearrangement during extrusion showed a dense structure in the SEM images. TGase addition contributed to the increase of β-sheet and water-holding capacity of the extrudates, and decrease of β-turn, tryptophan residues and oil-holding capacity, indicating that the stability of protein structure was related to hydrogen bond, disulfide bond and hydrophobic interaction. Furthermore, the apparent viscosity and denaturation degree were highest while 0.2% TGase was added. The ability to optimize the use of TGase can lead to better quality meat analogues, meeting the growing demand for alternative protein sources in the food market and providing more options for consumers who are seeking plant-based or reduced-meat diets. • TGase modifies the products of high moisture extrusion process. • TGase promotes the cross-linking of protein. • TGase accelerates the unfolding of protein molecules. • TGase modifies the structural and rheological characteristics of extrudates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Established a high lignocellulosic dry-wet combined anaerobic digestion system. • The kinetic parameters of the whole anaerobic digestion process were revealed. • Synergism between Clostridiales and methanogens was evaluated via network analysis. • Syntrophy between SFOB and methylotrophic Methanospirillum was observed. • The number of key acidogenic Clostridium was increased by 80.77–107.11%. Dry-wet combined anaerobic digestion is a novel approach for treating lignocellulosic waste by increasing the organic load of reactor while accelerating the conversion of organic acids. Here, we investigated the effect of regulated substrate ratios and initial pH in the dry acidogenesis stage on the bioconversion efficiency of dry-wet combined anaerobic digestion. Our data revealed microbial interactions and further identified key microbes based on microbial co-occurrence network analysis. On day three of acidification, the kinetic hydrolysis rate and acidification yield reached 1.66 and 60.07%, respectively; this was attributed to enhancement of the synergistic effect between Clostridiales and Methanosaeta , which increased the proportion of corn straw in the substrate or lowered the initial spray slurry pH to 5.5–6.5. With increased acidification capacity, acetoclastic methanogens were enriched in the wet methanogenesis stage; the syntrophic effect of Syntrophomonadales , Syntrophobacterales and Methanospirillum , meanwhile, was enhanced, leading to an overall improvement in biogas production. [ABSTRACT FROM AUTHOR]

Single-crystal chemical vapour deposition (CVD) diamond samples with asymmetric Schottky contacts were used for the fabrication of vertical metal-semiconductor-metal detectors for deep ultraviolet (UV–C) radiation. Spectral photoconductivity measurements, performed in the 190 ÷ 1100 nm wavelength range, returned an ultraviolet-to-visible (UV/Vis) rejection ratio of 6.8 × 103 under photovoltaic operating conditions, ensuring solar blindness and zero power consumption at the same time. When applying bias, UV/Vis rejection ratio reached excellent values (>104) even at very low electric fields (0.01 V/μm), thanks to the excellent structural quality and the superior charge transport properties of the diamond bulk, as inferred from Raman analysis and spectral photoconductivity measurements. Mobility-lifetime (μτ) product of the photogenerated carriers was indeed measured to be about 5 × 10−3 cm2/V in the case of holes, which is the highest room-temperature μτ value ever reported for CVD diamond, enabling a response speed in the nanosecond range even at zero-bias operating conditions. [Display omitted] • The concept of asymmetric Schottky contacts was applied for the first time to diamond UV-Cdetectors. • Self-powered operation was successfully demonstrated even under a weak (3.7 μW/cm2) UV-C light. • Nanosecond-response speed and a linear dynamic range of 80 dB were obtained. • A mobility-lifetime product of 5 × 10−3 cm2/V was measured for holes at room temperature. [ABSTRACT FROM AUTHOR]

Liquid digestate recirculation can fundamentally solve the problem of voluminous liquid digestate discharge for biogas projects. However, the uncertainty of the effect of recirculation under different feedstock restricts the application of recirculation technology. In this study, the comprehensive effects of straw to manure feeding ratios and liquid digestate recirculation on anaerobic digestion performance and microbial community structure were investigated. Recirculation was beneficial for biomethane production and digestion stability in digesters of corn stalk and straw/manure 3:1 by alleviating the loss of ammonia and alkalinity, while it aggravated the accumulation of ammonia and organic acids and reduced methane yield under 1:1, 1:3 and pig manure. The feeding ratios and recirculation formed a combined effect on ammonia concentration in the fermentation system, and when the total ammonia concentration was above 1500 mg/L, acids accumulation and decline in methane production would occur whether with recirculation or not. The microbial community structure varied corresponding to the fermentation state. In the well-run digesters, which were 3:1 with recirculation and 1:1 without recirculation, the dominant methanogens were Methanosaeta, while in the inhibited digesters, Methanosarcina and Methanosphaera dominated the methanogen community. Based on producing 1 GJ energy, the strategy of 3:1 with recirculation reduced the discharge of liquid digestate by 81.9% and the use of clean water by 65.4% compared to that of 1:1 without recirculation. An integrated approach of adjusting feedstock formula and selectively employing liquid digestate recirculation was proposed to produce liquid digestate on-demand with downstream application requirement, which will make biogas industry eco-friendly and cost-effective. Image 1 • Cross effects of liquid digestate reuse and feed-formula on performance and microbes. • Recirculation is beneficial when straw to manure ratio is 3:1 or higher in feedstock. • Recirculation mode ran well and reduced 81.9% liquid discharge and 65.4% water usage. • Cooperation of feedstock and recirculation may achieve controllably liquid discharge. [ABSTRACT FROM AUTHOR]

The heterostructures of graphitic carbon nitride (g-C 3 N 4) and CdS were synthesized by controlling the crystalline degree of g-C 3 N 4 and the phase composition of CdS. A thermal polycondensation process of N precursors was adjusted to get amorphous and crystalline g-C 3 N 4. A multistep adsorption method was used to deposit CdS nanoparticles on g-C 3 N 4. An annealed process was used to adjust the phase composition of CdS from cubic to hexagonal. The morphology of CdS was changed to rod. Amorphous g-C 3 N 4 /CdS heterostructures revealed enhanced photocatalytic activity because the amorphous g-C 3 N 4 has a lower crystallinity, it is easier to form a heterojunction with the CdS. Further, an annealing process resulted in the phase transfer and morphology change of CdS. The high stability and rod morphology of CdS make the heterostructures with high H 2 generation rate to 5440 μmol h-1 g-1 which is ~5 times high compared with g-C 3 N 4. g-C 3 N 4 /CdS hetrojunctions with crystallinity and phase controlling for high efficiency photocatalytic hydrogen generation. Image 1 • g-C 3 N 4 with different degrees of crystallinity was used to form a heterojunction with CdS. • The phase transition of CdS significantly improved its photocatalytic activity. • The heterojunction after the phase transition is greatly different due to difference in matrix. [ABSTRACT FROM AUTHOR]

Evaluation on urban commercial centers' attractiveness not only benefits business strategy making and location choice, but also helps traffic management and urban planning. Traditionally, it is studied using questionnaires and field research, which are labor-intensive and time-consuming. To overcome these problems when evaluating the urban commercial centers' attractiveness, massive data analytics with datasets from taxi traffic, population, area, and road networks are adopted in this paper. Taking fifteen commercial centers at Shenzhen as a case study, a Cyber-Physical-Social System is built up to deal with these massive data for statistical analysis. An "Attractiveness Degree Model" is proposed to describe the degree to which customers desire to visit a commercial center. Then attractiveness thematic maps are drawn. Results show that YiTianJiaRiGuangChang has the highest attractiveness degree even though it has a small size and low commercial value. The attractiveness degree rankings are corroborated by annual customer satisfaction survey from Shenzhen Retail Business Association. Attractiveness thematic maps show that about 50–65% visits by taxis are within 5 km range. These results can be applied to support market analysis, urban planning, traffic management, and related areas. • Commercial center is precisely defined geographically and sociologically. • Attractiveness degree is the proposed metric to evaluate the attractiveness. • A Cyber-Physical-Social System is implemented for massive data processing. • Statistical analysis and thematic maps shed new insights into attractiveness. • Commercial centers are classified into four representative types in China. [ABSTRACT FROM AUTHOR]

TiO 2 (B)/CdS/Au and TiO 2 (B)/Au/CdS heterostructures were synthesized to investigate the effect of the selected deposition of CdS and Au nanoparticles (NPs) on H 2 generation. TiO 2 (B) spheres (phase B) consisted of nanosheets were synthesized via a hydrothermal reaction. The deposition of CdS and Au NPs were carried out using wet-chemical method and a reduction reaction, respectively. The size and amount of Au and CdS NPs were adjusted to optimize the resulting properties and discuss the change of band gap. Two kinds of heterogeneous revealed different photocatalytic hydrogen generation which indicated the position of Au NPs affect the transfer of photogenerated carriers. The hydrogen production rate of TiO 2 (B)/CdS/Au heterostructures reached up to 12100 μmol g−1 h−1, which is about 3.8 times of that of pure TiO 2 (B) spheres. This is ascribed to the structure of heterostructures. CdS NPs increase the separation of photogenerated electrons and Au NPs accelerated the transfer of the electrons. The result provided a utilizable strategy for efficient photocatalysis H 2 generation. Image 1 • Two kinds of heterojunctions were successfully prepared. • TiO 2 (B)/CdS/Au and TiO 2 (B)/Au/CdS revealed different electron transport paths. • Heterojunctions improve the photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Hydroxyl ionic conductivities of anion exchange membrane with three different imidazolium group positions were studied. Models of Poly (aryl ether oxadiazole) anion-exchange membranes with the same degree of functionality were investigated by molecular dynamics simulation. Mean square displacement (MSD) was applied for hydroxyl ions, H 2 O and methanol diffusion coefficient calculation. The distance of N + –N + , N–OH–O was analyzed using radial distribution function (RDF). Simulation results shown that hydroxyl ions had more chances to appear around imidazole radical groups. The hydroxyl ionic conductivity of Line-type, Meta-type and Diagonal-type respectively were 7.74 × 10 −2 S·cm −1 , 4.66 × 10 −2 S cm −1 and 1.78 × 10 −2 S cm −1 . The diffusion rate of CH 3 OH molecules had the same trends with OH − particles, reducing from the Line-type to Diagonal-type. [ABSTRACT FROM AUTHOR]

Bioaugmentation using microbial consortia is helpful in some anaerobic digestion (AD) systems, but accelerated acidification to produce methane has not been performed effectively with corn stalks and cow dung. In this study, the thermophilic microbial consortia MC1 was inoculated into a complex open environment (unsterilized and sterilized systems) to evaluate the feasibility of bioaugmentation to improve acidification efficiency. The results indicated that MC1 itself degraded lignocellulose efficiently, and accumulated more organic acids within 3 days. Similar trends were also observed in the unsterilized system, where the hemicellulose degradation rate and organic acid concentrations increased significantly by two-fold and 20.1% (P < 0.05), respectively, and clearly reduced the loss of product. Microbial composition did not change obviously after inoculating MC1, but the abundance of members of MC1, such as Bacillus and Clostridium , increased clearly on day 3. Finally, the acidogenic fluid improved methane yield significantly (P < 0.05) via bioaugmentation. [ABSTRACT FROM AUTHOR]

• The "inhibited steady-state" was successfully constructed with C/Ns of 10–12. • Low- and high-C/N reactors are characterized by different marker taxa. • Methanosarcina can be as an indicator to aid ammonia inhibition judgment. • Competition among bacteria is rich and leads to low performance. • H 2 /CO 2 pathway became the dominant methanogenesis pathway at low C/N. The carbon/nitrogen ratio (C/N) is a key parameter that affects the performance of anaerobic digestion (AD). Recent AD research has focused on optimizing the C/N of feedstock. The so-called "inhibited steady-state" refers to a special state of ammonia inhibition of AD that often occurs at low-C/N (below 25) when degradable nitrogen-rich substrates, such as livestock manure, are used as feedstock. However, the mechanism behind the "inhibited steady-state" is still unknown. In the current study, co-digestion and recirculation were used to create a C/N gradient in the influent to explore the relationship between substrates, metabolites, and microorganisms in the "inhibited steady-state." Data were collected at the macro, microbial, and genetic levels. Three CSTRs were successfully made run into the "inhibited steady-state" using influent C/Ns of 10–12. Digestion performance levels of R10–R12 were low and stable, transitioning from an aceticlastic methane-producing pathway to a hydrogenotrophic pathway as the C/N gradually decreased. As the abundance of the hydrogenophilic methanogens increased, the abundance of syntrophic acetate-oxidizing bacteria (SAOB) also increased. The succession between populations of Methanosaeta and Methanosarcina may be used as a microbiological indicator of ammonia inhibition. Under high-C/Ns, cooperation among bacteria was high, while under low-C/Ns, competition among bacteria was high. These results clarify the processes underlying the "inhibited steady-state," which is a condition often faced in actual large-scale biogas facilities that use degradable nitrogen-rich substrates. Moreover, practical guidelines for evaluating ammonia inhibition are provided, and strategies to alleviate ammonia suppression are developed. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Pretreatment is essential for maize straw to accelerate methane production in AD. • Enzymatic pretreatment boosted the initial VFAs yield and changed its composition. • The highest cumulative methane yield was obtained with a 2/3 ratio of ETv/EAs. • Enzymes stimulated the abundance of bacterial related to cellulose degradation. Biological pretreatment is a promising technology to increase biogas yield. The methane yield and microbial community resulting from anaerobic digestion of maize straw after pretreatment of enzymes [extracted from Trichoderma viride (ETv) and Aspergillus sp. (EAs)] at different mixing ratios [5/0, 4/1, 3/2, 2/3, 1/4, 0/5] were evaluated. The methane yields from mixed enzymes pretreatment were higher than single enzymes pretreatments of ETv and EAs. The optimal enzymes mixing ratio of ETv and EAs was found to be 2/3, with the cumulative methane yield 512.64 mL/g TS added , which was 31.74% higher than the control. Enzymatic pretreatment promoted an increase in the abundance of bacteria and archaea associated with cellulose decomposition. The majority of bacteria and archaea were assigned to Bacteroidetes , Firmicutes and Methanosaeta. [ABSTRACT FROM AUTHOR]