Characterizing the Opportunity Space for Sustainable Hydrothermal Valorization of Wet Organic Wastes.

Resource recovery from wet organic wastes can support circular economies by creating financial incentives to produce renewable energy and return nutrients to agriculture. In this study, we characterize the potential for hydrothermal liquefaction (HTL)-based resource recovery systems to advance the economic and environmental sustainability of wastewater sludge, FOG (fats, oils, and grease), food waste, green waste, and animal manure management through the production of liquid biofuels (naphtha, diesel), fertilizers (struvite, ammonium sulfate), and power (heat, electricity). From the waste management perspective, median costs range from -193 $·tonne-1 (FOG) to 251 $·tonne-1 (green waste), and median carbon intensities range from 367 kg CO2 eq·tonne-1 (wastewater sludge) to 769 kg CO2 eq·tonne-1 (green waste). From the fuel production perspective, the minimum selling price of renewable diesel blendstocks are within the commercial diesel price range (2.37 to 5.81 $·gal-1) and have a lower carbon intensity than petroleum diesel (101 kg CO2 eq·MMBTU-1). Finally, through uncertainty analysis and Monte Carlo filtering, we set specific targets (i.e., achieve wastewater sludge-to-biocrude yield >0.440) for the future development of hydrothermal waste management system components. Overall, our work demonstrates the potential of HTL-based resource recovery systems to reduce the costs and carbon intensity of resource-rich organic wastes.

A comprehensive review on integrating sustainable practices and circular economy principles in concrete industry.

This comprehensive review explores the integration of circular economy principles into the concrete industry, emphasizing their role in enhancing sustainability and resource efficiency. It covers the fundamental concepts of circular economy and examines the application of Life Cycle Assessment (LCA) in evaluating the environmental impacts of concrete production. The review highlights innovative strategies for recycling, reuse, waste reduction, and resource optimisation, showcasing how these approaches can transform concrete production practices. It also addresses the policy considerations, economic implications, and societal impacts associated with adopting circular economy practices. Furthermore, the review investigates recent technological advancements in circular concrete production, including self-healing concrete and 3D printing. By summarizing these findings and offering practical recommendations, the review aims to support the industry in transitioning towards more sustainable practices. This detailed analysis provides valuable insights into the benefits and challenges of circular economy adoption, helping stakeholders make informed decisions for a greener concrete sector.

Life cycle assessment perspective on waste resource utilization and sustainable development: A case of glyphosate production.

The growing demand for pesticide manufacturing and increasing public awareness of sustainable development, have let to urgent requirements for a refined environmental management framework. It is imperative to conduct process-based life cycle assessments (LCAs) to promote clean and environment-friendly technologies. Herein, the cradle-to-gate LCA of glyphosate production was executed as an example to investigate crucial production factors (materials or energy) and multiple environmental impacts during the production processes. Results showed that methanol caused the highest environmental damage in terms of toxicity, with a normalized value of 85.7 × 10-8, followed by coal-fired electricity in 6.00 × 10-8. Furthermore, optimized schemes were proposed, including energy improvement (electricity generated by switching from coal-fired power to solar power) and wastewater targeted conversion. Regarding the normalization results before and after optimization, the latter showed more significant results with the normalized value decreasing by 21.10 × 10-8, while that of the former only decreased by 6.50 × 10-8. This study provides an integrated LCA framework for organophosphorus pesticides (OPs) from upstream control and offers an important supplement to managing the key pollution factors and control links of the OP industry. Moreover, it reveals the positive influence of optimized schemes in facilitating cleaner production technologies, thus ultimately promoting new methodologies for resource recycling.

Environmental sustainability assessment of biodegradable bio-based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from agro-residues: Production and end-of-life scenarios.

In the context of a circular bio-based economy, more public attention has been paid to the environmental sustainability of biodegradable bio-based plastics, particularly plastics produced using emerging biotechnologies, e.g. poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV. However, this has not been thoroughly investigated in the literature. Therefore, this study aimed to address three aspects regarding the environmental impact of PHBV-based plastic: (i) the potential environmental benefits of scaling up pellet production from pilot to industrial scale and the environmental hotspots at each scale, (ii) the most favourable end-of-life (EOL) scenario for PHBV, and (iii) the environmental performance of PHBV compared to benchmark materials considering both the pellet production and EOL stages. Life cycle assessment (LCA) was implemented using Cumulative Exergy Extraction from the Natural Environment (CEENE) and Environmental Footprint (EF) methods. The results show that, firstly, when upscaling the PHBV pellet production from pilot to industrial scale, a significant environmental benefit can be achieved by reducing electricity and nutrient usage, together with the implementation of better practices such as recycling effluent for diluting feedstock. Moreover, from the circularity perspective, mechanical recycling might be the most favourable EOL scenario for short-life PHBV-based products, using the carbon neutrality approach, as the material remains recycled and hence environmental credits are achieved by substituting recyclates for virgin raw materials. Lastly, PHBV can be environmentally beneficial equal to or even to some extent greater than common bio- and fossil-based plastics produced with well-established technologies. Besides methodological choices, feedstock source and technology specifications (e.g. pure or mixed microbial cultures) were also identified as significant factors contributing to the variations in LCA of (bio)plastics; therefore, transparency in reporting these factors, along with consistency in implementing the methodologies, is crucial for conducting a meaningful comparative LCA.

Sustainable repurpose of end-of-life fiber reinforced polymer composites: A new circular pedestrian bridge concept.

In response to global challenges in resource supply, many industries are adopting the principles of the Circular Economy (CE) to improve their resource acquisition strategies. This paper introduces an innovative approach to address the environmental impact of waste Glass Fiber Reinforced-Polymer (GFRP) pipes and panels by repurposing them to manufacture structural components for new bicycle and pedestrian bridges. The study covers the entire process, including conceptualization, analysis, design, and testing of a deck system, with a focus on the manufacturing process for a 7-m-long prototype bridge. The study shows promising results in the concept of a sandwich structure utilizing discarded GFRP pipes and panels, which has the flexibility to account for variabilities in dimensions of incoming products while still meeting mechanical requirements. The LCA analysis shows that the transportation of materials is the governing contributing factor. It was concluded that further development of this concept should be accompanied by a business model that considers the importance of the contributions from the whole value chain.

A sustainable recycling process and its life cycle assessment for valorising post-consumer textile materials for thermal insulation applications.

The textile industry along with construction, electronics and plastic generate huge amounts of waste posing challenges to the adoption of the circular economy. This research presents a sustainable and low-cost recycling technology for conversion of post-consumer textile (denim) wastes to useful insulation materials. To accomplish the objective, nonwoven materials were produced using varying proportions of post-consumer recycled denim (r-denim) fibre and hollow polyester (PET) fibre using different punch densities in the needle punching process. Kowalski, Cornell and Vining mixture design, a special type of design of experiments, was adopted to develop the samples. Developed nonwoven materials were characterised for thermal resistance and tensile properties. The results show that nonwoven materials containing the minimum proportion (20%) of r-denim fibres exhibited the highest thermal resistance (0.131 W-1m2K). However, by adjusting the process parameter of the nonwovens, that is, the punch density, the same thermal resistance (0.131 W-1m2K) is also achieved even with 39% r-denim fibres. Additionally, the nonwovens produced from this blend proportion (r-denim:PET = 39:61) demonstrate a reasonable strength of 2.43 cN/tex. Environmental benefits of the developed r-denim/PET nonwovens have been evaluated by the life cycle assessment approach. Results show that the use of ~40% r-denim fibre has reduced the environmental burden significantly. Therefore, the nonwoven materials produced from post-consumer textile wastes hold tremendous potential as an alternative to synthetic fibres in thermal insulation applications. This recycling approach has immense potential to contribute to the efficient utilisation of post-consumer textile waste materials paving the way for environmental sustainability.

Harmonized Life-Cycle Inventories of Nanocellulose and Its Application in Composites.

Cellulose nanocrystals (CNC) and nanofibers (CNF) have been broadly studied as renewable nanomaterials for various applications, including additives in cement and plastics composites. Herein, life cycle inventories for 18 previously examined processes are harmonized, and the impacts of CNC and CNF production are compared with a particular focus on GHG emissions. Findings show wide variations in GHG emissions between process designs, from 1.8-1100 kg CO2-eq/kg nanocellulose. Mechanical and enzymatic processes are identified as the lowest GHG emission methods to produce CNCs and CNFs. For most processes, energy consumption and chemical use are the primary sources of emissions. However, on a mass basis, for all examined production methods and impact categories (except CO emissions), CNC and CNF production emissions are higher than Portland cement and, in most cases, are higher than polylactic acid. This work highlights the need to carefully consider process design to prevent potential high emissions from CNCs and CNF production despite their renewable feedstock, and results show the magnitude of conventional material that must be offset through improved performance for these materials to be environmentally favorable.

Improved Machine Learning Models by Data Processing for Predicting Life-Cycle Environmental Impacts of Chemicals.

Machine learning (ML) provides an efficient manner for rapid prediction of the life-cycle environmental impacts of chemicals, but challenges remain due to low prediction accuracy and poor interpretability of the models. To address these issues, we focused on data processing by using a mutual information-permutation importance (MI-PI) feature selection method to filter out irrelevant molecular descriptors from the input data, which improved the model interpretability by preserving the physicochemical meanings of original molecular descriptors without generation of new variables. We also applied a weighted Euclidean distance method to mine the data most relevant to the predicted targets by quantifying the contribution of each feature, thereby the prediction accuracy was improved. On the basis of above data processing, we developed artificial neural network (ANN) models for predicting the life-cycle environmental impacts of chemicals with R2 values of 0.81, 0.81, 0.84, 0.75, 0.73, and 0.86 for global warming, human health, metal depletion, freshwater ecotoxicity, particulate matter formation, and terrestrial acidification, respectively. The ML models were interpreted using the Shapley additive explanation method by quantifying the contribution of each input molecular descriptor to environmental impact categories. This work suggests that the combination of feature selection by MI-PI and source data selection based on weighted Euclidean distance has a promising potential to improve the accuracy and interpretability of the models for predicting the life-cycle environmental impacts of chemicals.

Evaluating Sustainable Development Pathways for Protein- and Peptide-Based Bioadsorbents for Phosphorus Recovery from Wastewater.

Recovering phosphate (P) from point sources such as wastewater effluent is a priority in order to alleviate the impacts of eutrophication and implement a circular economy for an increasingly limited resource. Bioadsorbents featuring P-binding proteins and peptides offer exquisite P specificity and sensitivity for achieving ultralow P concentrations, i.e., <100 µg P L-1, a discharge limit that has been implemented in at least one treatment facility in nine U.S. states. To prioritize research objectives for P recovery in wastewater treatment, we compared the financial and environmental sustainability of protein/peptide bioadsorbents to those of LayneRT anion exchange resin. The baseline scenario (reflecting lab-demonstrated performance at a full-scale implementation) had costs that were 3 orders of magnitude higher than those for typical wastewater treatment. However, scenarios exploring bioadsorbent improvements, including increasing the P-binding capacity per unit volume by using smaller P-selective peptides and nanoparticle base materials and implementing reuse, dramatically decreased median impacts to $1.06 m-3 and 0.001 kg CO2 equiv m-3; these values are in line with current wastewater treatment impacts and lower than the median LayneRT impacts of $4.04 m-3 and 0.19 kg CO2 equiv m-3. While the financial viability of capturing low P concentrations is a challenge, incorporating the externalities of environmental impacts may provide a feasible path forward to motivate ultralow P capture.

A comparative environmental analysis of conventional and organic rice farming in Thailand in a life cycle perspective using a stochastic modeling approach.

System stochasticity is an inherent characteristic of agricultural systems. Many studies have been conducted in Thailand to analyze the rice production systems. However, most of the prior work just focused on deterministic approach to investigate the rice production systems while disregarding the system variability. In this study, the conventional and organic rice farming systems in Thailand were compared considering the uncertainties associated with parameters. The system variability was taken into account by employing a stochastic modeling approach. The considered impact categories include global warming, ozone formation (human health), freshwater ecotoxicity, terrestrial acidification, fine particulate matter formation, freshwater eutrophication, and fossil resource scarcity. The results showed that yield had considerable influence on the environmental profiles of the two systems; organic and conventional farming showed similar results in terms of global warming on a per hectare basis, but the considerable difference was observed on a per tonne basis. The field emissions due to farm inputs were the most significant contributor to most of the impact categories. The fuel used for irrigation, land preparation, and harvesting also contributed significantly to several impact categories. On the other hand, the impacts of inputs production and material transportation were modest. Uncertainty analysis outcomes indicated that there was a noticeable deviation from the deterministic results in terms of global warming and freshwater ecotoxicity. However, when considering the associated uncertainties, no significant difference was observed between the environmental profiles of the two systems.

Environmental impacts and improvement potentials for copper mining and mineral processing operations in China.

There has been growing concern among the public over the environmental impacts of the copper (Cu) mining and mineral processing industries. As an effective tool enabling interactions of all energy and material flows with the environment, Life Cycle Assessment (LCA) is used in many countries to identify environmental hotspots associated with operations, based on which improvements can be made. However, robust LCA research in this sector is lacking in China. This study aimed to fill this critical gap by investigating two typical Cu mining and mineral processing operations using different mining technologies, based on globally harmonized LCA methodologies. The results of the overall environmental impacts were obtained using a sensitivity analysis. Electricity (38%-74%), diesel (8%-24%) and explosives (4%-22%) were identified as the three main controlling factors. At the same time, the mineral processing stage was found to be the major production stage (60%-79%), followed by the mining stage (17%-39%) and the wastewater treatment (1%-13%). Global Warming Potential (GWP) was prioritized as the most important environmental issue (59%) across the selected impact categories. In addition, it was initially found that underground mining technology has better environmental performance than open-pit technology. Finally, the potential for improvement was estimated and discussed for the three identified controlling factors. Using GWP as an example, using green electricity can effectively reduce CO2 emissions by 47%-67%, whereas replacing diesel and explosives with cleaner fuels and explosives may contribute to lower CO2 emissions by 6% and 9%, respectively.

Towards credible, evidence-based environmental rating ecolabels for consumer products: A proposed framework.

Environmental rating ecolabels are a new generation of ecolabels. They are intended to enable consumers to compare the environmental impacts of multiple products and make more sustainable consumption choices. Falling outside of the three types defined in the ISO 14020 environmental label and declarations series, the recent proliferation of these business-to-consumer communication instruments has resulted in the creation of a plethora of methodologies to derive product performance ratings. Interest from consumers wanting more information on the products they purchase, as well as the promise of policy instruments aiming to increase transparency and combat greenwashing, are fuelling further multiplication of schemes. A move towards more credible, evidence-based environmental rating ecolabels is therefore urgently needed to promote assessment based on scientific understanding, gain consumer trust, and realise policy objectives. We propose a framework based on four core principles - i) relevance, ii) scientific robustness, iii) trust and transparency, and iv) feasibility (scalability, affordability) - with 18 guidelines that can be followed by rating scheme developers. We characterise the rise of environmental rating ecolabels in geographical Europe and build an inventory of 33 existing schemes, at various stages of development and implementation, to which we apply the framework. This reveals the potential for significant improvement in current schemes, indicating important areas for development. The framework provides a valuable guide for the development of new schemes or an evaluation grid for existing initiatives.

Life-LCA: case study of the life cycle impacts of an infant.

Purpose: The recently published first Life-LCA case study of a human being (0-49 years) did not use primary data for the "childhood and youth stage" (0-17 years). Consumption was assumed to contribute 50% of the calculated 48th baseline year. This led to uncertainties as consumer behavior changes from birth to adulthood. Furthermore, transport emissions and environmental impacts before birth were neglected. Therefore, this paper analyzes the prenatal and infancy phase (0-3 years) to develop the Life-LCA method and database further and evaluate generic assumptions. Methods: The Life-LCA method sets the reporting unit to newly defined prenatal and infancy phases. The reporting flow describes the range of all consumed products attributable to an infant. Primary data was collected with a sample of three study objects-a pregnant mother, a newborn baby, and a 3-year-old infant-living in Germany. The following environmental impact assessment categories are considered: climate change (GWP), acidification (AP), eutrophication (EP), and photochemical ozone creation (POCP). Results and discussion: Prenatal and infancy phase burdens account for a GWP of 4,011 kg CO2-eq., an AP of 22.3 kg SO2-eq., an EP of 10.7 kg PO4-eq., and a POCP of 1.7 kg C2H4-eq. The share of the prenatal phase is around 15-20% for all impact categories. Transport is a hotspot for GWP (30-60%) and POCP (45-70%) in both phases. AP (50%) and EP (45-50%) are dominated by food products, mainly meat (45%) and dairy products (35%). For the prenatal phase, energy and water consumption at birth rank third in GWP (8%). Diapers account for 6% (GWP) of the environmental burden in the infancy phase. Assumptions made in the first Life-LCA study connect closely with the values calculated for the first three years of infancy. A remaining challenge is allocating the impacts between infants and parents and developing a methodology for assessing data quality. Conclusion: Focusing on two new life phases has led to the subdivision of the "childhood and youth stage" and an extension of the system boundaries. The results' uncertainty was reduced by developing a new set of specific datasets focusing on several study objects. The case study results show the importance of primary data collection for evaluating generic assumptions. Additional studies on childhood and adolescence from 3 to 17 years are suggested for a robust assessment of the complete "childhood and youth stage." Supplementary Information: The online version contains supplementary material available at 10.1007/s11367-022-02129-7.

Nanotechnologies for environmental remediation and their ecotoxicological impacts.

Environmental nanoremediation is an emerging technology that aims to rapidly and efficiently remove contaminants from the polluted sites using engineered nanomaterials (ENMs). Inorganic nanoparticles which are generally metallic, silica-based, carbon-based, or polymeric in nature serve to remediate through chemical reactions, filtration, or adsorption. Their greater surface area per unit mass and high reactivity enable them to treat groundwater, wastewater, oilfields, and toxic industrial contaminants. Despite the growing interest in nanotechnological solutions for bioremediation, the environmental and human hazard associated with their use is raising concerns globally. Nanoremediation techniques when compared to conventional remediation solutions show increased effectivity in terms of cost and time; however, the main challenge is the ability of ENMs to remove contaminants from different environmental mediums by safeguarding the ecosystem. ENMs improving the accretion of the pollutant and increasing their bioavailability should be rectified along with the vigilant management of their transfer to the upper levels of the food chain which subsequently causes biomagnification. The ecosystem-centered approach will help monitor the ecotoxicological impacts of nanoremediation considering the safety, sustainability, and proper disposal of ENMs. The environment and human health risk assessment of each novel engineered nanomaterial along with the regulation of life cycle assessment (LCA) tools of ENMs for nanoremediation can help investigate the possible environmental hazard. This review focuses on the currently available nanotechnological methods used for environmental remediation and their potential toxicological impacts on the ecosystem.

Impact of smallholder cattle farms on the environment: a study.

With increasing evidence of global warming, the pressure is building to limit greenhouse gas emission from many human activities including dairy production systems. In this context, the present study was conducted to estimate the carbon footprint (CF) of cattle milk produced in the Hisar district of Haryana, India. The data about feeding practices, crops grown, manure management systems, etc. was collected through personal interviews with cattle-rearing rural male farmers chosen through multistep random sampling. The life cycle assessment (LCA) methodology was adopted to estimate carbon footprint, with the system boundary being "Cradle to farm gate." The latest methodologies prescribed by the IPCC were used to estimate GHG emissions using the tier-2 approach. The current study has presented a detailed and recent GHG inventory from smallholder cattle farms at the village level. On the basis of the inventory analysis, a simplified life cycle-based analysis is used in order to quantify the carbon footprint of fat- and protein-corrected milk (FPCM). The carbon footprint of cattle milk was estimated at 2.13 kg CO2-eq/kilogram FPCM. Enteric fermentation was the most potent contributor to GHG, contributing around 35.5% of the total emissions, followed by manure management (13.8%) and soil management (8.2%). Further studies to accurately estimate carbon footprint are advocated besides suggesting ways to reduce GHG emissions and using efficient production technologies.

Environmental impacts of rare earth production.

Rare earth elements (REEs) are important raw materials for green technologies. However, REE mining and production uses techniques that are often not environmentally sustainable. Life cycle assessment (LCA) is a well-recognized method for evaluating the environmental impacts of products and technologies. This article provides an overview of the environmental impacts based on published LCA results of primary REE production. Existing major REE deposits (Bayan Obo in China, Mountain Pass in the United States, Mount Weld in Australia, ion-adsorption deposits in several Chinese southern provinces) and currently possible production routes are compared. Alternative minerals, such as eudialyte, are also discussed. The article shows which environmental effects can be minimized by technology optimization and environmental safety strategies. Additionally, some of the environmental impacts discussed, may be difficult to mitigate, as they depend on the mineral type. Activities along the complex process chain of REEs production that have particularly high environmental impacts are identified.

Environmental and Socioeconomic Impacts of Poly(ethylene terephthalate) (PET) Packaging Management Strategies in the EU.

Plastics are a challenge for the circular economy due to their overall low recycling rate and high dependency on primary resources. This study analyzes the EU demand for poly(ethylene terephthalate) (PET) packaging from 2020 to 2030 and quantifies the potential environmental and societal savings by changing the waste management and consumption patterns compared with business-as-usual practices. The results of the life-cycle assessment and life-cycle costing show that a maximum of 38 Mt of CO2-eq and 34 kt of PM2.5-eq could be saved with a more efficient waste management system and a robust secondary material market while also avoiding 8.3 billion EUR2019 in societal costs (cumulative 2020-2030). However, limiting annual PET consumption growth appears to have a similar profound effect on improving the efficiency of waste management systems: 35 Mt of CO2-eq, 31 kt of PM2.5-eq, and 25 billion MEUR2019 societal costs could be saved, simply by keeping EU consumption of PET constant.

Life cycle assessment of heavy metal contaminated sites: phytoremediation and soil excavation.

Phytoextraction by native Taiwanese chenopod (Chenopodium formosanum Koidz.) and Napier grass (Pennisetum purpureum) for heavy metals such as chromium (Cr), nickel (Ni), and copper (Cu) was reported first. Maximum bioconcentration factors of Cu and Cr were 8.8 and 12.5 by Taiwanese chenopod. Napier grass cultivar Taishi No.4 plants demonstrated higher survivals than that of Taiwanese chenopod, under heavy metal stress in soils. All heavy metal accumulation and biomass data were employed, as well as historical engineering data were collected for conventional excavation-and-refill remediation of two sites. Life cycle assessment (LCA) was conducted for comparing environmental performances of phytoextraction and conventional remediation for two contaminated sites. Assuming one-year growth, three harvests were done and biomass was collected and sent to the nearest municipal incinerators, phytoextraction by both plants demonstrated superior environmental performances than conventional methods for contaminated site remediation. High quantities of fuels to haul the soils of conventional methods mainly contributed to the greenhouse gas emission. Phytoextraction has the most advantages for sites with lesser extents of pollution and time restraints. Environmental performances of phytoremediation were even better if energy recovered from biomass incineration is counted. Novelty statement Phytoextraction by native Taiwanese chenopod and Napier grass was firstly reported. Life cycle assessment was conducted for comparing the phytoextraction and conventional remediation. Phytoextraction demonstrated superior environmental performances. Energy reutilization of biomass recovered made phytoremediation more sustainable.

Environmental synergies in decentralized wastewater treatment at a hotel resort.

Climate change and water scarcity are clearly related environmental problems, making them global environmental issues. Accordingly, the water cycle management deserves a revision in its approach, integrating the concept of circular economy within an efficient and sustainable management of water resources and the design of wastewater facilities. In this sense, newly engineered decentralized facilities have emerged as a viable option for the treatment of segregated wastewater flows. The design has not only integrated the wastewater treatment function, but also resource recovery, such as water reclamation for agricultural and irrigation activities, fertigation, fertilization and energy sustainability. Based on these premises, the concept of decentralized wastewater management deserves the same degree of attention and development that has so far been reserved for conventional centralized management systems. Therefore, this paper proposes a progressive substitution of the business-as-usual scenario or centralized system by applying a small-scale wastewater management scheme performing a more efficient resource and water recovery in a medium-sized 4-5-star resort hotel. The spotlight was a membrane technology for the anaerobic digestion of the blackwater instead of the greywater treatment. A favorable environmental profile was found for the decentralized scenario under two circumstances: a large system boundary including the beneficial environmental impacts of the products and, based on the results obtained from a sensitivity analysis, an energy demand for the operation of the AnMBR lower than 2 kWh·m-3. The global warming potential results (around 9%) were even for such high demand and much larger benefits were obtained for other impact categories (94% for SOD and 98% for LU). Nevertheless, the operation (gate-to-gate approach) of these on-site recovery facilities is far from being optimized and further research should follow to decrease the 39.8% difference in the global warming potential between decentralized and centralized systems.

Environmental assessment of recycling waste corrugated cartons from online shopping of Chinese university students.

College students in China are among the main consumers of online shopping and the corrugated cartons used to ship items are piling up on campus. However, the generation characteristics of waste corrugated cartons (WCCs) in universities and the environmental consequences along their recycling pathway remain to be addressed. Taking Nanjing University (NJU) as an example, this study conducted a questionnaire survey on campus to analyze the generation characteristics of WCCs and evaluated the life cycle environmental impacts of their recycling process using the Life Cycle Assessment (LCA) method. The results showed that WCC generation on campus varied by educational level, sex, grade and major, with doctoral students and female students being more active in online shopping and thus generating more WCCs. It was further estimated that a total of 0.27 Mt of WCCs were generated by college students in China in 2020, of which recycling would result in 0.31 Mt of CO2 eq of GHG emissions. Pulping and papermaking processes are the main contributors to the life cycle environmental impacts of WCC recycling, together accounting for at least 77% of the total. This study suggests the need for joint efforts from universities, students, and recycling enterprises to reduce WCC generation in Chinese universities and to make its recycling chain more environmentally sustainable.