Environmental performance of straw-based pulp making: A life cycle perspective

Carbon reduction and water saving potentials for growing corrugated boxes for express delivery services in China

Corrugated packaging for express grew by 90 times to 16.5 Mt y-1 in China, where 81% of recent global express delivery growth occurred. However, the environmental impacts of production, usage, disposal, and recycling of corrugated boxes under the entire supply chain remain unclear. Here, we estimate the magnitudes, drivers, and mitigation potentials of cradle-to-grave life-cycle carbon footprint (CF) and three colors of water footprints (WFs) for corrugated cardboard packaging in China. Over 2007 to 2021, CF, blue and gray WFs per unit package decreased by 45%, 60%, and 84%, respectively, while green WF increased by 23% with growing imports of virgin pulp and China's waste ban. National total CF and WFs were 21 to 102 folded with the scale effects. Only a combination of the supply chain reconstruction, lighter single-piece packaging, and increased recycling rate can possibly reduce the environmental footprints by 24 to 44% by 2035.

Exploration of the Linkages between Lignin and Carbohydrates in Kraft Pulp from Wheat Straw Using a 13C/2H Isotopic Tracer

To further our understanding of the change in association between lignin and carbohydrates after kraft pulping, isotope-labeled kraft pulp (KP) was prepared using 13C and D double-isotope-labeled wheat straw, and it was subjected to enzymatic hydrolysis and ionic liquid treatment to explore the linkages between lignin and carbohydrate complexes in wheat straw. Isotope abundance determination showed that 13C and D abundances in the experimental groups were substantially higher than those in the control group, indicating that the injected exogenous coniferin-[α-13C], coniferin-[γ-13C], and d-glucose-[6-D2] were effectively absorbed and metabolized during wheat internode growth. Solid-state CP/MAS 13C-NMR spectroscopy showed that lignin was mainly linked to polysaccharides via acetal, benzyl ether, and benzyl ester bonds. Kraft pulp (KP) from the labeled wheat straw was degraded by cellulase. The obtained residue was fractionated using the ionic liquid DMSO/TBAH to separate the cellulose-lignin complex (KP-CLC) and xylan-lignin complex (KP-XLC). X-ray diffractometer determination showed that the KP-CLC regenerated cellulose type II from type I after the ionic liquid conversion. The 13C-NMR spectrum of Ac-En-KP-CLC showed that the cellulose-lignin complex structure was chemically bonded between the lignin and cellulose through acetal and benzyl ether bonds. The 13C-NMR spectrum of En-KP-XLC showed a lignin-hemicellulose complex structure, wherein lignin and xylan were chemically bonded by benzyl ether and acetal bonds. These results indicate that the cross-linking between lignin and carbohydrates exists in lignocellulosic fibers even after kraft pulping.

Chemical pulp from corn stalks

This work aimed to carry out chemical cooking of corn stalks, both in a nitrate-alkaline manner and in a soda pulp method. The composition of corn is characterized by cellulose, lignin, ash, and substances extractable into polar and organic solvents. Handsheets were made from the pulp, for which the degree of polymerization, sedimentation rate, and strength properties was determined.

Non-wood fibers as raw material for pulp and paper industry

Pulp and paper industry in the world have been growing fast. As a result, there has been a massive request for pulp and paper raw materials. The raw materials used in papermaking can be classified into three groups: wood, non-wood, and recycled wastepaper. The Non-wood raw material is an important fiber resource in the regions where forest resources are limited. The current usage of non-wood plant fibers, as rice straws, corn stalks, cotton stalks, and bagasse would play a chief role in increasing papermaking raw materials. Using of non-wood plant fibers in the paper industry associated with some problems, including collection, transportation, storage and handling, washing, bleaching, papermaking, chemical recovery, supply of raw material and the properties of finished paper. Recently, a high-tech innovation in all the fields of papermaking has made non-wood more reasonable with wood as a raw material for papermaking. Although till now, use of non-wood fibers for pulp and paper manufacture was focused in countries with limited wood supply, it is now showing a growing effort even in countries with acceptable wood source due to environmental concerns. Consequently, the future of non-wood plant fibers as pulping and papermaking raw material looks bright.

Multi-criteria decision making for sustainability assessment of boxboard production: A life cycle perspective considering water consumption, energy consumption, GHG emissions, and internal costs

Papermaking is a capital-intensive industry that requires a high consumption of plant fibers, energy, and water. Previous sustainability assessments of papermaking industry primarily focused on separate evaluations for multiple criteria without the integration for criteria and could not compare the overall priority of the production alternatives. The life cycle sustainability for the most representative boxboard production is analyzed as a case study in this work. Life cycle water consumption, energy consumption, greenhouse gas emissions, and internal costs are selected as the assessment criteria. The two multi-criteria decision-making methods are applied to integrate the above criteria to obtain the sustainability sequence under different production pathways. When the papermaking enterprises are regarded as decision-makers, the alternative using waste paper as raw material to manufacture boxboard is the most sustainable, following by mixed fiber. The sustainability sequence of the alternatives using wood and straw as raw materials is controversial due to the different calculation models. Changing the proportion of raw materials and the criteria weights might adjust sustainability sequence of the alternatives.

Knowledge domain and emerging trends of agricultural waste management in the field of social science: A scientometric review

Many studies have been conducted on agricultural waste management, especially review articles; however, there are few literature analyses from the scientometric and bibliometric perspective. This study is one of the first to offer insights into the research topics and trend evaluation in terms of agricultural waste management over time. Our main findings are as follows: For nearly half a century, the United States has maintained the leading position in research on agricultural waste management. Many core research institutions or scholars are also from the United States. There are four major areas in this field: the research on the low-carbon and energy utilization of agricultural waste, the influence of agricultural waste emissions, the material and energy flow of agricultural waste and the prevention and control of agricultural waste pollution. As time progresses and with the development of environment, economy and society, the popular research topics in different stages vary, but on the whole, the research on agricultural waste management has emerged in the early stage. With the change of global natural resource conditions and political and economic background, there are more space for the future. We believe that research on greenhouse gas emission reduction from agricultural waste management based on specific social policies is extremely urgent, and will be of great significance in reducing agricultural greenhouse gas emission.

Ecotoxicological effects of fertilizers made from pulping waste liquor on earthworm Eisenia fetida

In recent years, increasing efforts have focused on production of organic-inorganic compound fertilizers using ammonium sulfite pulping waste liquor. However, their ecological effects on soil have not been studied. In this study, earthworm Eisenia fetida was exposed to various doses (0, 0.13, 0.26 and 0.52 kg/m²) for different time (7, 14, 21, and 28 d) to evaluate the effects of fertilizers made from pulping waste liquor, including reactive oxygen species (ROS) generation, antioxidant enzymes activities, glutathione S-transferase enzyme (GST) activity, malondialdehyde (MDA) content and DNA damage. Results showed that there were significant increase of ROS and MDA levels after 14 d, inducing production of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT)) as well as GST. Before 14 d, excess ROS and MDA caused damage to the DNA of earthworms, leading to gradual increase of Olive tail moment (OTM) in the comet assay. With the exposure time extended to 28 d, owing to the combined effects of elimination of free radicals by antioxidant enzymes and detoxification enzymes as well as self-repairing function of cells, ROS and MDA levels declined slightly and OTM gradually decreased. In summary, this study indicated that there was a toxicological effect on earthworms when fertilizers made from pulping waste liquor were applied to soil, which needs more attention.

Sustainability evaluation and implication of a large scale membrane bioreactor plant

Membrane bioreactor (MBR) technology is receiving increasing attention in wastewater treatment and reuse. This study presents an integral sustainability evaluation of a full scale MBR plant. The plant is capable of achieving prominent technical performance in terms of high compliance rate, low variation in effluent quality and high removal efficiency during long term operation. It is also more responsive to the new local standard with rigorous limits. However, electricity consumption is found to be the dominant process resulting in elevated life cycle environmental impacts and costs, accounting for 51.6% of the costs. As such, it is suggested to optimize energy use in MBR unit and implement sludge treatment and management. The prolonged membrane life span could also contribute largely to reduced life cycle environmental concerns and expenses. This study is of great theoretical significance and applicable value in guaranteeing the performance and sustainability of large scale MBR schemes.

Life-cycle assessment of tobacco stalk utilization

The aim of this work was to investigate the environmental performance of different tobacco stalk methods using Life Cycle Assessment (LCA). Three scenarios were established: biodegradable plant nursery tray (PNT) making, open burning, and indoor incineration. The results showed that 3380, 1590, 1320 kg CO2-eq, 25.7, 1.97,1.99 kg SO2-eq are generated for global warming and acidification in biodegradable PNT making, open burning, and indoor incineration scenarios respectively. The overall environmental impact for biodegradable PNT making is higher than that of open burning, and indoor incineration. The dominant factors contributing to environmental impact in biodegradable PNT making include electricity consumption, solid waste landfill etc. Through technical optimization, the environmental impact of biodegradable PNT making could be reduced greatly. Biodegradable PNT making with tobacco stalk, which follows the cyclic economy principles of maximum material utilization and waste minimization, provides an alternative for agricultural residue utilization.