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• The insertion of an MgO buffer layer significantly reduces the large lattice mismatch between FeRh and PMN-PT. • The FeRh(001) film is epitaxially grown on the ferroelectric PMN-PT(001) substrate. • The epitaxial FeRh(001) film displays multi-step hysteresis loops at various field orientations at 350 K. • The butterfly shape of coercivity vs electric field indicates a strain-mediated magnetoelectric coupling. • The transition temperature and the magnetization are enhanced and reduced in the remnant polarization state, respectively. We epitaxially grew the metamagnetic FeRh films on ferroelectric PMN-PT(001) substrates and investigated the electric control of magnetic properties. An MgO buffer layer is inserted to reduce the considerably large lattice mismatch of 5.44% between FeRh and PMN-PT, leading to a nice epitaxial growth with a relationship of FeRh[110](001)||MgO[100](001)||PMN-PT[100](001). The as-grown FeRh film shows a typical antiferromagnetic-to-ferromagnetic phase transition by means of varying the temperature. Because a growth-induced uniaxial magnetic anisotropy is superimposed on the in-plane four-fold magnetocrystalline anisotropy, the epitaxial FeRh film displays different kinds of multi-step hysteresis loops at various field orientations. An electric field applied on the PMN-PT substrate can remarkably increase the coercivity of FeRh film, which presents a butterfly type shape, indicating a strain-mediated magnetoelectric coupling. Because of the inhibitory effect of the remnant compressive strain on the phase transition, the critical transition temperature and the magnetization are obviously enhanced and reduced, respectively, after removing the electric effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-digestion of 45.7% BPS, 26.2% SCB and 28.1% CM produced 186.5 mL/g VS methane. • This co-digestion strategy provided a synergistic effect of 37.1% on methane yield. • A higher microbial diversity was found in co-digestion due to the balanced nutrition. • The predominant microorganisms in co-digestion were Choroflexi with a proportion of 39.3%. • Enriched hydrogenotrophic Methanobacterium and Methanolinea were found at high OLR. Balanced nutrition is important for maximizing anaerobic digestion (AD) performance. Herein, the strategy of balancing sugar-fiber-nitrogen nutrients was first established for improved methane production by co-digesting two agricultural and one livestock wastes with complementary compositional properties, such as banana pseudo-stem (BPS), sugarcane baggage (SCB), and chicken manure (CM) having high sugar, fiber and nitrogen contents, respectively. The maximum methane yield was 186.5 mL/g VS added with a mixture of 45.7% BPS, 26.2% SCB and 28.1% CM (with 1: 11.3: 0.3 of sugar to fiber to nitrogen ratio), increasing by 16.1%, 53.3%, 122.6% than those of mono- BPS, SCB, and CM, respectively. The co-digestion process remained stable under an organic load of 4 g VS/(L·day), which was attributed to the predominant presence of Bacteroidetes, Proteobacteria, Thauera , uncultured_bacterium_p_Aegiribacteria , and hydrogenotrophic methanogens. This study provides a deeper understanding of the co-digestion with agricultural and livestock wastes from the perspective of nutrient balance. [ABSTRACT FROM AUTHOR]

The sustainability of biogas production from straws is limited by the collection, transportation, storage, and pretreatment of feedstocks. To address these constraints, this study investigated briquetting as a pretreatment strategy for rice straw (RS) to increase bioenergy generation. The results indicated that briquetted RS yielded 205.4 mL/g VS of methane, which was 11.7% higher compared to that produced by the untreated RS. The economic analysis revealed that the briquetting process had positive effects with a payback time of 3.4 y and an internal rate of return of 23.4%. It also reduced feedstock transportation and storage costs by 42.6%. Adding a NaOH treatment to the briquetting process increased methane production by 26.4% compared to untreated RS. However, the integration of briquetting with NaOH treatment might be an unprofitable method for processing RS. This became apparent when examining the production cost, which stood at 1.13 $/kg biomethane with an internal rate of return of 16.2%, representing an 8.7% increase and a 7.2% decrease, respectively, compared to the mono briquetting method. These results revealed that briquetting as a source pretreatment strategy can improve the productivity of straw biogas plants, thereby advancing the industry towards cleaner production. [Display omitted] • Briquetting, a source pretreatment strategy, improved straw biogas production. • The briquetting strategy integrates the collection and pretreatment of rice straw. • The proposed strategy reduced straw transportation and storage costs by 42.6%. • Adding an NaOH treatment reduced the profitability of a straw biogas plant. [ABSTRACT FROM AUTHOR]

• High moisture content is a prominent feature of banana pseudo-stems (BPS). • The effect of squeezing pretreatment on methane production from BPS was evaluated. • Methane production increased by 41.2% after pretreating BPS by squeezing. • Most phenols were lost with the BPS juice during squeezing. • Energy output from squeezed BPS exceeded energy consumption during pretreatment. Banana pseudo-stems (BPS) are an abundant and low-lignin-content lignocellulosic biomass for methane production. However, the high-water content in BPS increases the transport costs, and the resistant structure of BPS hinders methane production. In this study, squeezing of BPS as a pretreatment was evaluated for improving anaerobic digestion (AD). After 20-d digestion, methane production from squeezed BPS was 204.2 ± 6.2 mL/(g volatile solids (VS) of feedstock), which was 41.2% more than that from untreated BPS. This increase was mainly attributed to the improvement of physical properties (e.g. water absorbing capacity) and the change in the resistant structure of BPS after squeezing, which promoted good contact between microbes and substrate during AD. The measured methane production was described using a modified Gompertz model and the results showed that anaerobic process would take less time and occur faster when pretreated BPS was used as the substrate. The energy produced during AD of squeezed BPS, after deducting the energy used by the squeezer, resulted in an energy surplus of 26.2%. [ABSTRACT FROM AUTHOR]

• A novel hydraulic digester with the ability to control scum formation was developed. • Improved biogas yield and feedstock degradation were achieved in conical digesters. • The conical shapes increased the diversity and evenness of the archaea community. • The digester was operated in batch and continuous modes. Scum formation is a widespread phenomenon and causes serious damage in straw biogas digesters. A 10-L novel hydraulic conical digester for controlling scum was developed in this work and compared with a hydraulic cylindrical digester that simulated the conventional digester. After 30 d of batch and 120 d of semi-continuous fermentations using banana stems, the scum volumes of in cylindrical digesters were 4.12 and 2.12 times that in the conical digesters, respectively. The conical digesters increased biogas production by 5.7% and 11.6% in batch and semi-continuous tests, respectively. The VS removal of feedstock in conical digesters were 5.6 and 7.2% greater than for the batch and semi-continuous cylindrical, respectively. The microbial diversity and evenness were higher in conical than cylindrical digesters. The results demonstrated that conical shape was an effective structure for controlling scum formation and improving biogas production. [ABSTRACT FROM AUTHOR]