Review Articles

This review article considers factors contributing to the development of problematic levels of foam, as well as ways to control foam, with emphasis on two critically important unit operations in pulp and paper manufacturing plants, namely the brownstock washing system and the paper machine. In general terms, hard-to-break foam bubbles can be expected when an aqueous system is subject to a means of air entrainment (such as agitation), when an air phase is present, when there are surface-active agents present, and when the solution also contains significant levels of water-soluble polymers. Brownstock washers and paper machines have all of these ingredients, and sometimes they are at problematic levels. The resulting stabilized foam bubbles can hurt production rates, interfere with displacement of pulping liquor from the fiber mat during washing, and contribute to blemishes in paper products. Considerable progress has been made over many years in understanding these phenomena and also in understanding the work of foam-control products. Engineers in modern pulp and paper mills can make use of efficient foam-control products as well as monitoring equipment. This article provides a tutorial review of such issues, based on published findings.

Establishing an economically efficient supply chain for biomass feedstock is a critical prerequisite for achieving large-scale bioenergy development under China’s “dual carbon” strategy. Focusing on agro-forestry residue feedstocks, this paper systematically reviews the technologies and models for the key stages of their collection, storage, and transportation (CST) system. The inherent physicochemical characteristics of biomass, such as low bulk density and high moisture content, constitute a fundamental physical bottleneck that constrains its economic viability. To this end, pretreatment technologies, with densification at their core, are widely recognized as a critical technological stage for enhancing logistics efficiency and achieving value addition. In contrast to the technological optimization of individual stages, systemic integration strategies—such as establishing a hybrid “decentralized-centralized” supply chain model and employing multi-modal transport—represent a more effective pathway to achieving whole-chain cost reduction and efficiency enhancement. Through a systematic integration of research in this field, this paper emphasizes that the key to resolving CST bottlenecks lies in adopting a whole-chain perspective that involves the deep coupling of essential pretreatment technologies with innovative supply chain organizational models.

Microalgae-derived biodiesel is increasingly regarded as a next-generation renewable fuel because microalgae combine rapid biomass growth, high lipid productivity, carbon dioxide capture, and cultivation on non-arable land or nutrient-rich wastewater. This review critically integrates recent progress in strain improvement, cultivation engineering, harvesting, lipid extraction, and conversion technologies for scalable biodiesel production. Advances in genome editing, two-stage cultivation, hybrid photobioreactor-open pond systems, and microwave- or ultrasound-assisted extraction have improved lipid yield and process efficiency. Digital tools, including artificial intelligence, predictive monitoring, digital twins, and machine-learning-based contaminant control, are also emerging as important enablers of automation and scale-up. Embedding microalgae production within circular biorefineries can support flue-gas utilization, nutrient recycling, and co-production of high-value compounds such as astaxanthin, omega-3 fatty acids, phycobiliproteins, proteins, and biodegradable biopolymers. Nevertheless, commercialization remains constrained by high cultivation costs, energy-intensive dewatering, variable outdoor productivity, and uncertain policy incentives. Integrated techno-economic optimization, carbon-credit mechanisms, and multi-product biorefinery models are therefore essential for advancing microalgae biodiesel toward industrial deployment.

Published findings are reviewed related to the recovery and recycling, as well as the biodegradability, of single-use food packaging materials that include waterborne barrier coating layers. Such layers can replace petroleum-based plastics, such as polyethylene, which tend to build up in the environment and contribute to microplastics issues. Barrier layers, of either type, can block the transport of oxygen, water vapor, liquid water, grease, contaminants, and flavors in and out of such packaging systems.  Key concerns include whether such layers can be readily dispersed in water, thereby allowing the packaging material to be used again in subsequent generations of recycled paper products. The process efficiency, including the yield of recovered materials, is also of concern. Because single-use food packaging products, in most regions, are not yet routinely routed to paper recycling, this review also considers findings related to biodegradability and compostability of waterborne barrier layers. Based on the reported findings, there are numerous waterborne formulations that can meet practical needs in terms of biodegradability and repulpability, leading to relatively high yields in paper recycling operations. Chemical components of future waterborne coating formulations need to be considered on a case-by-case basis regarding their contributions to toxicity, compostability, general biodegradability, and circular systems of recovery and reuse.

Bamboo (subfamily Bambusoideae, Poaceae) represents one of the most taxonomically complex and evolutionarily dynamic lineages within grasses due to irregular flowering cycles, extensive morphological plasticity, frequent hybridization, and widespread polyploidy. These characteristics have historically complicated species delimitation and phylogenetic reconstruction. This review synthesizes recent advances in integrative bamboo systematics, emphasizing the roles of phylogenomics, molecular cytogenetics, DNA barcoding, multi-locus sequencing, and computational morphological analytics in resolving bamboo diversity and evolutionary relationships. Genome-wide sequencing approaches have enabled the detection of hybridization events and reticulate evolutionary histories that were previously difficult to resolve using morphology or single-locus markers. These advances have improved phylogenetic resolution, particularly among closely related bamboo taxa. Nevertheless, incongruence between nuclear and plastid datasets, incomplete lineage sorting, and polyploid genome complexity continue to constrain full phylogenetic resolution. Integrative systematic approaches provide an essential framework for improving taxonomic stability, biodiversity conservation, and sustainable management within Bambusoideae.

During the production of fuel ethanol, biogas, and organic fertilizer from whole grains, mycotoxins in the feedstock raise complex issues regarding product safely. In fuel ethanol production, processes such as grinding, liquefaction, and fermentation can cause structural transformations or reductions in the levels of certain toxins (such as zearalenone and vomitoxin); however, degradation products may remain in the distillers’ grains protein feed, affecting the safety of the byproduct. During the biogas fermentation stage, anaerobic microbial communities can further degrade some toxins through enzymatic reactions and metabolic processes. The degradation efficiency is significantly influenced by feedstock characteristics, process parameters, and toxin types, and small amounts of toxins or their transformation products may still remain in the digested liquid. In the subsequent organic fertilizer production process, the high-temperature phase of composting helps reduce residual toxins, and the synergistic action of aerobic microorganisms enhances degradation. However, certain mycotoxins may not be completely degraded or may generate unknown metabolites, posing potential ecological and health risks after application to farmland. Elucidating the degradation mechanisms, transformation pathways, and product safety of mycotoxins during multi-stage sequential treatment is important for ensuring pollution control across the entire industrial chain and the safe utilization of resource-recycled products.

The sape is a traditional stringed instrument of the indigenous communities of Borneo that has evolved from its ritual origins into a symbol of cultural identity and contemporary relevance. This review examines more than 25 academic works across ethnomusicology, acoustic and engineering studies, soundboard quality and machine learning, music education, and health-related research. Existing studies address topics ranging from tonal behaviour and material assessment to cultural heritage, pedagogy, and therapeutic applications. While the literature demonstrates growing interdisciplinary interest, significant gaps remain, particularly in indigenous participation, documentation of traditional repertoires, and integration across research domains. This review highlights the need for culturally grounded and community-engaged approaches to support the continued transmission and sustainability of the sape.

Biomass gasification for synthetic natural gas (SNG) production has emerged as a promising pathway for renewable energy utilization and the low-carbon energy transition. This review comprehensively summarizes the key technologies involved in Bio-SNG conversion, focusing on feedstock pretreatment, gasification, syngas conditioning, and methanation. The influences of typical pretreatment methods, including torrefaction and hydrothermal carbonization, on feedstock reactivity and tar formation are critically analyzed. Furthermore, the effects of different gasifier configurations and gasifying agents in regulating syngas quality are compared in detail. The article systematically elaborates the research progress in tar, sulfur, and chlorine impurity removal, water-gas shift (WGS) reaction and H₂ addition through Power-to-Gas (PtG) for H₂/CO ratio adjustment, Ni-based methanation catalysts, and heat-transfer-intensified reactors. Moreover, the inherent limitations and potential improvement strategies of current technologies are discussed, including instability in gasification performance caused by feedstock variability, catalyst deactivation from multiple impurities, coking and sintering during methanation, and thermal management challenges associated with highly exothermic reactions. Finally, Bio-SNG technology is transitioning from individual process optimization toward integrated and synergistic full-process development, which is expected to facilitate the large-scale commercial deployment of this technology.

Dissolving-grade pulp (DGP) is a high-purity cellulose feedstock used in the manufacture of regenerated cellulose fibers and cellulose derivatives. Global DGP production is concentrated in regions with established forest-based industries and relies primarily on virgin lignocellulosic resources, including cotton linters, hardwoods, softwoods, and bamboo. These raw materials are typically processed through acid sulfite or prehydrolysis kraft pulping to achieve alpha-cellulose contents above 90%. Compared with virgin feedstocks, recycled fibers exhibit greater variability in morphology and chemical composition, including shorter fiber lengths, lower cellulose quality, and higher levels of residual lignin, ash, inks, fillers, coatings, and other papermaking additives. Consequently, major waste paper streams, such as old corrugated container (OCC), old newspaper (ONP), old magazine (OMG), sorted office paper (SOP), and mixed paper (MP), present distinct challenges for meeting DGP quality specifications. Producing DGP from these secondary fiber resources requires the application of key pulp and paper processing technologies, including repulping, screening, advanced washing and deinking, delignification and bleaching, selective hemicellulose removal through alkaline and enzyme-assisted treatments, and cellulose reactivity enhancement. This review evaluates the technical feasibility of producing DGP from waste paper and highlights both the challenges and opportunities associated with valorizing recycled fibers as a sustainable source of high-purity cellulose.