Understanding nitrogen dynamics in the Brazilian beef industry: A comprehensive decadal analysis

Brazil stands as a prominent beef producer and exporter, witnessing major transformations and expansions in its production chain over the past 20 years. These changes have prompted concerns regarding waste generation and environmental pressure. This study employs material flow analysis (MFA) to quantify nitrogen flows throughout the cattle slaughter process and subsequent beef consumption in Brazil, spanning from 2011 to 2021. The analysis encompasses co-production streams like leather, tallow, viscera, and blood. Nitrogen use efficiency (NUE) and the nitrogen cascade indicator (NCI) were used to evaluate efficiency and nitrogen accumulation in the production chain. Nitrogen inputs in the system increased by 8.47 %, while beef production rose by 7.29 %. In contrast, per capita beef consumption decreased by 1.29 kg, despite an overall consumption increase of 2.84 %, attributed to population growth in Brazil. Beef exports witnessed a notable surge of 86.03 %. Conversely, human excreta and food waste losses experienced increments of 10.88 % and 2.84 %, respectively. Examining NUE reveals the highest values during the slaughter phase (90 %), followed by processing, transportation, and storage stages (79-88 %). The consumption phase exhibited the lowest NUE values (29-34 %). Regarding the cumulative nitrogen effect, the NCI varied between 77 % and 82 % throughout the study period. This highlights opportunities for enhancing nitrogen use efficiency, particularly by addressing food waste at the consumer level. Notably, the study observes nitrogen accumulation across the Brazilian beef production chain, potentially contributing to the nitrogen cascade effect and heightening environmental pressure. Recognizing these dynamics provides avenues for targeted improvements, emphasizing the need to address nitrogen-related challenges and enhance sustainability in the beef production and consumption landscape.

Material flow analysis and statistical entropy evaluation of plastic packaging for express delivery in China

Encouraging the recycling of plastic packaging materials in express delivery is a necessary step toward environmentally friendly industrial development. In this study, we present a framework for analyzing the flow of materials in express plastic packaging, from production and manufacturing to consumption and recycling. In examining the use of recycled materials in post-consumer express plastic packaging and the destination of consumer packaging waste in 2020 and 2021, we found that 44.4% (1613.6 Gg) of the studied express plastic packaging was incinerated. Additionally, approximately 1296.6 Gg of express plastic packaging flowed into rural areas. Our calculations showed that the ΔRSE in 2020 was 15.1%, and on the condition that 25% separated collection with 80% recycling, ΔRSE would be - 0.5%. Results verified that separated collection is an important step in the recycling strategy for packaging materials. Survey data from universities in Beijing indicate that currently, 26% of college students are participating in the separate collection of packaging.

Carbon reduction trade-off between pretreatment and anaerobic digestion: A field study of an industrial-scale biogas plant

With the implementation of municipal solid waste source segregation, the enormous sorted biogenic waste has become an issue that needs to be seriously considered. Anaerobic digestion, which can produce biogas and extract floating oil for biodiesel production, is the most prevalent treatment in China for waste management and greenhouse gas (GHG) emissions reduction, in accordance with Sustainable Development Goal 13 of the United Nations. Herein, a large-scale biogas plant with a capacity of 1000 tonnes of biogenic waste (400 tonnes of restaurant biogenic waste and 600 tonnes of kitchen biogenic waste) per day was investigated onsite using material flow analysis, and the parts of the biogas plant were thoroughly analyzed, especially the pretreatment system for biogenic waste impurity removal and homogenization. The results indicated that the loss of the total biodegradable organic matter was 41.8% (w/w) of daily feedstock and the loss of biogas potential was 18.8% (v/v) of daily feedstock. Life cycle assessment revealed that the 100-year GHG emissions were -61.2 kgCO2-eq per tonne biogenic waste. According to the sensitivity analysis, pretreatment efficiency, including biodegradable organic matter recovery and floating oil extraction, considerably affected carbon reduction potential. However, when the pretreatment efficiency deteriorated, GHG benefits of waste source segregation and the subsequent biogenic waste anaerobic digestion would be reduced.

Investigating the characteristics of combustible fraction of legacy waste: A study on energy recovery potential and GHG emission quantification

In India, majority of the generated municipal solid waste (MSW) was dumped in poorly managed landfills and dumpsites over the past decades and is an environmental and health hazard. Landfill mining is a promising solution to reclaim these sites along with the recovery of resources (materials and energy). During landfill mining operations, the combustible fraction is one of the major components recovered and needs proper management for maximizing resource recovery. For the identification of appropriate resource recovery options, knowledge of the physicochemical characteristics is required. The present study aims to assess the depth-wise change in the composition of legacy waste and the physicochemical characteristics of the combustible fraction. Furthermore, a material flow analysis considering the incineration of combustible fraction was performed to estimate the energy generation potential and the associated greenhouse gas (GHG) emissions. The results of the compositional analysis of dry legacy waste revealed that the fine fraction (<4 mm soil-like material) was dominating with a share of 36%. The depth-wise analysis showed a decrease in the calorific value with increasing landfill depth, while no specific trend was observed for the other parameters analyzed, including proximate and ultimate analysis, and chlorine content. The material flow analysis performed for 100 tonnes of wet legacy waste indicated that 52 tonnes of waste is combustible fraction. The GHG emissions through incineration of one tonne of dry combustible fraction would be 1389 kg CO2-eq, with 1125 kWh of electrical energy generation potential.

Tracing wastewater resources: Unravelling the circularity of waste using source, destination, and quality analysis

Current circularity assessment terminology restricts application to wastewater processes due to the focus on technical systems. Waste stream and wastewater discharge circularity definitions lead to paradoxical assessments that generate results of little value for evidence-based decision making. Therefore, a classification approach was developed to measure inflow and outflow circularity of the main wastewater resource flows using the principle of traceability, adopting the attitude that not all waste is created equally. Applying it to a wastewater treatment plant (12,000 m3/d load) showed how upstream agricultural, industrial, and human practices impact downstream treatment, and the effectiveness of resource cycling within the natural environment. Industrial actions increasing fossil carbon concentration (400 m3/d effluent at 1000 mgC/l) reduced inflow and outflow circularity by 16 % and 10.6 % respectively, as secondary and sludge treatment fossil emissions increase significantly. Alternatively, changes to human and agricultural practices (50 % reduction of detergent and synthetic fertiliser usage) improved phosphorus inflow and nitrogen outflow circularity by 5.2 % and 20.1 % respectively. This approach can educate and assign responsibility to water users for developing robust circular economy policy, shifting the pattern from promoting circularity to discouraging linear actions, overcoming the shared economic and environmental burden of linear water use.

Spatial-temporal differentiation and control strategies of nitrogen environmental loss in China's coastal regions based on flow analysis

Nitrogen pollution emissions from human production and living activities in coastal regions are important topics in the management of environmental pollution in coastal waters. However, to date, there has been relatively little research systematically assessing the environmental loss of nitrogen (NEL) from human activities that negatively affect marine ecosystems. This study categorised emission sources into five subsystems, namely livestock, farming, aquatic, industrial, and residential. Through flow analysis, the anthropogenic emissions of nitrogen in the gas, liquid, and solid phases from 11 coastal provinces in China in 2011, 2015, and 2020 were determined. A nitrogen cost index was constructed by combining the social indicators of each province. The effectiveness of nitrogen emission control since the land-sea coordination and the future challenges for the coastal region were discussed from various perspectives. The results of the study showed that the total NEL that poses a potential threat to marine ecosystems in coastal areas of China has decreased from 18.93 TgN to 14.66 TgN since the proposal of land-sea coordination, with livestock systems and aquatic systems emitting the most. The Bohai and Yellow Seas area were most threatened by nitrogen pollution. Among the three oceanic pathways, liquid-phase nitrogen discharge from each subsystem was effectively controlled, and the control of gas-phase nitrogen emissions is still the most numerous NEL state, although it has had a significant effect. The results of the correlation analysis suggest that NEL flow can characterize the regional management of nutrient-based organic pollutants. Past management tools and environmental investments in China have been more effective in controlling emissions from point and line sources involving artificial facilities, but less direct effect on mariculture. How to control surface source pollution from livestock and aquaculture will be an important challenge to reduce reactive nitrogen emissions in the future.

Plastic impurities in biowaste treatment: environmental and economic life cycle assessment of a composting plant

The study focuses on an Italian composting plant and aims to investigate the impact of the presence of plastic impurities in the collected biowaste on the environmental and economic performance of the plant. The study is divided into two main steps: firstly, a material flow analysis was conducted to quantify the number of impurities (e.g., conventional plastics and compostable plastics) before and after the composting process. Secondly, a life cycle assessment (LCA) and a complementary life cycle costing (LCC) of the composting process were conducted. The results of the material flow analysis confirmed the initial assumption that conventional plastic remains almost constant before and after the composting treatment, while compostable plastic almost disappears. As far as the life cycle analyses are concerned, the most environmentally damaging phases of the process were the shredding and mixing phases, while the operating costs (OPEX) contributed the most to the total annual costs of the company. Finally, a further scenario analysis was performed, assuming that the plastic contaminants in the treated biowaste consisted exclusively of compostable plastics. The comparison with this ideal scenario can support decision-makers to understand the potential improvements achievable by addressing the presence of plastic impurities in the biowaste. The results show that the treatment of plastic impurities causes relevant environmental and economic impacts, being responsible for 46% of the total waste to treat at the end of the process, almost 7% of the total annual costs covered by the plant owners, and about 30% of all negative externalities.

Revealing the management of municipal textile waste and citizen practices: The case of Catalonia

Although the number of studies assessing the textile sector is increasing, only a few focus on its waste management. This study aims to shed light on current textile waste disposal practices and account for their environmental impact. To do so, a combination of citizen surveying and environmental quantitative tools, such as material flow analysis and life cycle assessment, are used to assess municipal textile waste in Catalonia in 2020. The results show that only approximately 10 % of municipal textile waste is separately collected, while 90 % is landfilled/incinerated. Of the 10 % of textiles collected separately, almost 40 % are prepared for reuse and recycled in Catalonia and Spain, approximately 40 % are exported for reuse and recycling in Asia, Africa and the rest of Europe, and the remaining 20 % are incinerated or landfilled, stocked or treated as improper waste. The carbon footprint generated by 1 t of textile waste managed by unseparated collection is 353 kg CO2 eq, which almost double that of 1 t of textile waste collected separately: 207 kg CO2 eq. The results also show that the emissions of textiles collected separately could be considerably reduced by minimizing their exports. The conclusions indicate that a proper course of action includes raising awareness about textile waste management and secondhand buying habits among citizens while investing in better sorting and local recycling technologies to reduce exports. Identifying the existing limitations to creating a local reuse and recycling textile sector is crucial to reduce its carbon footprint.

Predicting environmental concentrations of nanomaterials for exposure assessment - a review

There have been major advances in the science to predict the likely environmental concentrations of nanomaterials, which is a key component of exposure and subsequent risk assessment. Considerable progress has been since the first Material Flow Analyses (MFAs) in 2008, which were based on very limited information, to more refined current tools that take into account engineered nanoparticle (ENP) size distribution, form, dynamic release, and better-informed release factors. These MFAs provide input for all environmental fate models (EFMs), that generate estimates of particle flows and concentrations in various environmental compartments. While MFA models provide valuable information on the magnitude of ENP release, they do not account for fate processes, such as homo- and heteroaggregation, transformations, dissolution, or corona formation. EFMs account for these processes in differing degrees. EFMs can be divided into multimedia compartment models (e.g., atmosphere, waterbodies and their sediments, soils in various landuses), of which there are currently a handful with varying degrees of complexity and process representation, and spatially-resolved watershed models which focus on the water and sediment compartments. Multimedia models have particular applications for considering predicted environmental concentrations (PECs) in particular regions, or for developing generic "fate factors" (i.e., overall persistence in a given compartment) for life-cycle assessment. Watershed models can track transport and eventual fate of emissions into a flowing river, from multiple sources along the waterway course, providing spatially and temporally resolved PECs. Both types of EFMs can be run with either continuous sources of emissions and environmental conditions, or with dynamic emissions (e.g., temporally varying for example as a new nanomaterial is introduced to the market, or with seasonal applications), to better understand the situations that may lead to peak PECs that are more likely to result in exceedance of a toxicological threshold. In addition, bioaccumulation models have been developed to predict the internal concentrations that may accumulate in exposed organisms, based on the PECs from EFMs. The main challenge for MFA and EFMs is a full validation against observed data. To date there have been no field studies that can provide the kind of dataset(s) needed for a true validation of the PECs. While EFMs have been evaluated against a few observations in a small number of locations, with results that indicate they are in the right order of magnitude, there is a great need for field data. Another major challenge is the input data for the MFAs, which depend on market data to estimate the production of ENPs. The current information has major gaps and large uncertainties. There is also a lack of robust analytical techniques for quantifying ENP properties in complex matrices; machine learning may be able to fill this gap. Nevertheless, there has been major progress in the tools for generating PECs. With the emergence of nano- and microplastics as a leading environmental concern, some EFMs have been adapted to these materials. However, caution is needed, since most nano- and microplastics are not engineered, therefore their characteristics are difficult to generalize, and there are new fate and transport processes to consider.

Knowns and unknowns of plastic waste flows in the Netherlands

Plastic entering the environment is a growing threat for ecosystems. We estimate the annual mass of known Dutch plastic waste generated and littered and where it ends up. We use two methods: (1) a material flow analysis of plastic waste separately collected from 13 economic sectors (including households, industry and imports) and estimate the amount sent to processing plants or exported and (2) a mismanagement model from observations of litter (on Dutch beaches and riverbanks) plus estimates of inadequately managed exported plastic scraps entering the environment abroad. In 2017 (the most recent complete data set available), an estimate of 1990 (±111) kilotonnes [kt] of plastic waste was separately collected. The top three plastic waste generating sectors (74% of the total) were households, clothing and textiles, and importation. Our mismanagement model estimates that 4.3-21.2 kt enters the environment annually; almost all of which occurs in foreign countries after inadequate management of imported Dutch waste. We highlight unknowns, including the source and/or destination of imported (623 kt) and exported (514 kt) plastics, plastics in non-household mixed waste streams and the plastic fraction of some separately collected waste, for example, e-waste. Our results stress the need for improved monitoring and reporting of plastic waste. Beyond the Netherlands, our recommendations could also help other high-income countries' decision-makers reach their circular economy goals.

Regional nitrogen budgets of agricultural production systems in Austria constrained by natural boundary conditions

Nitrogen (N) budgets are valuable tools to increase the understanding of causalities between agricultural production and N emissions to support agri-environmental policy instruments. However, regional agricultural N budgets for an entire country covering all major N flows across sectors and environmental compartments, which also distinguish between different N forms, are largely lacking. This study comprehensively analyses regional differences in N budgets pertainting to agricultural production and consumption in the largely alpine and spatially heterogeneous country of Austria. A special focus is on the interconnections between regional agricultural production systems, N emissions, nitrogen use efficiencies (NUE), and natural boundary conditions. Seven regional and one national balance are undertaken via material flow analysis and are analysed with regards to losses into soils, water bodies and atmosphere. Further, NUE is calculated for two conceptual systems of plant and plant-livestock production. The results reveal major differences among regions, with significant implications for agri-environmental management. The high-alpine region, characterized by alpine pastures with a low livestock density, shows consequent low N inputs, the lowest area-specific N outputs and the most inefficient NUE. In contrast, the highest NUE is achieved in a lowland region specialized in arable farming with a low livestock density and a predominance of mineral fertilizer over manure application. In this region, the N surplus is almost as low as in the high-alpine region due to both significantly higher N inputs and outputs compared to the high-alpine region. Nevertheless, due to low precipitation levels, widespread exceedances of the nitrate target level concentration take place in the groundwater. The same issue arises in another non-alpine region characterized by arable farming and high livestock densities. Here, the highest N inputs, primarily via manure, result in the highest N surplus and related nitrate groundwater exceedances despite an acceptable NUE. These examples show that NUE alone is an insufficient target and that adapted criteria are needed for different regions to consider natural constraints and specific framework conditions. In a geographically heterogeneous country like Austria, the regional circumstances strongly define and limit the scope and the potential effectiveness of agricultural N management strategies. These aspects should be integrated into the design, assessment and implementation of agri-environmental programmes.

Analysis of the coupled flows of aluminum and copper in household air conditioning system

The global "copper-poor and aluminum-rich" situation has made the possibility of "copper saving with aluminum" an important topic. This study established a framework for analyzing multiple substances' coupled flows at the product level based on material flow analysis (MFA), and took the household air conditioning system of the Chinese mainland in 2020 as an example to characterize the coupled flows of aluminum and copper. The results showed that the system consumed 0.69 million tons of aluminum and 2.10 million tons of copper, and discharged 0.17 million tons of aluminum and 0.43 million tons of copper to the environment cumulatively to achieve 13.2 million terajoules of final heat exchanged and serve 1.24 billion square meters during lifetime in mainland China alone, secondary aluminum and copper accounted for only 22.61% and 24.83% of the total consumption, and the in-use stocks increased by 0.19 million tons of aluminum and 0.70 million tons of copper. The external dependency of copper ore was 92.83%, which was significantly higher than the 44.29% of bauxite. The comprehensive utilization efficiency of copper reached 77.88%, which was slightly higher than the 70.80% of aluminum. The conclusion indicates that under the premise of meeting use requirements, promoting "replacing copper with aluminum" can improve the stability and safety of China's material supply chain, but there is a need to further boost the production efficiency of aluminum in primary production.

Matching end-of-life household vehicle generation and recycling capacity in Chinese cities: A spatio-temporal analysis for 2022-2050

End-of-life vehicles (ELVs) present both opportunities and challenges for the environment and the economy, where effective recycling management plays a decisive role. Recently, the primary focus of recycling management has shifted from simply meeting demand to refining and optimizing processes at the city-scale. However, the mismatch in recycling capacity has become a significant obstacle to maximizing environmental and economic benefits. To reveal this issue and propose improvements in the context of China, this study simulates end-of-life internal combustion engine vehicles (ICEVs) and new energy vehicles (NEVs) at the city-scale from 2021 to 2050, and analyzes their spatio-temporal pattern and recycling capacity matching. The results indicate that the number of ELVs in China will continue to increase, peaking between 3.5 and 3.7 million. This growth will be mainly driven by third- to fifth-tier cities, as well as central and southwestern cities. Regarding recycling capacity matching, most cities possess excess dismantling capacity, while first-tier cities face coordination problems in battery collection. Spatial coordination across cities or provinces is a viable approach for dismantling enterprises and should be prioritized over indiscriminate deregistration or establishing new facilities. The absence of initiative within the recycling system results in uncoordinated battery collection. Implementing a recycling-sharing mechanism and establishing a reuse market can effectively tackle this problem by leveraging market incentives. These analyses provide practical suggestions to maximize the environmental and economic benefits of resource recycling, thereby contributing to the UN's 2030 Sustainable Development Goals (SDGs).

Material flow analysis on the critical resources from spent power lithium-ion batteries under the framework of China's recycling policies

With the rapid growth of electric vehicles in China, the number of spent power lithium-ion batteries is dramatically increased. Considering the environmental risk, security risk, and potential resource value, China has issued a series of laws and regulations to manage the spent power lithium-ion batteries. This work employs the material flow analysis method to evaluate the material flows of Li, Ni, Co, and Mn during the life cycle of power lithium-ion batteries under the framework of China's recycling policy system. The results show that the demand for primary Li, Ni, Co, and Mn can achieve 26.9, 68.1, 20.4, and 21.9 kt in 2021, and a lot of primary critical resources will inburst the in-use stage. Moreover, the number of secondary Li, Ni, Co, and Mn can achieve 6.1, 15.4, 4.6, and 5 kt in 2021, accounting for 22.7%, 22.6%, 22.5%, and 22.8% of their corresponding demand. Based on the economic evaluation under the framework of China's recycling policy system, it is found that the potential recycling values of Li, Ni, Co, and Mn are approximately 966, 523, 414, and 43 million RMB yuan, which are 66.4%, 71%, 59.6%, and 66.4% higher than those in the absence of China's recycling policy system. It is implied that China's recycling policy system could markedly improve the collection rate by reducing losses and indirectly enhancing the recycling and reuse of spent power lithium-ion batteries. This work is expected to provide guidance for policymakers to improve the management of spent power lithium-ion batteries in China.

Material flow analysis-based assessment of polypropylene-fiber-containing microplastics released from disposable masks: Characterizing distribution in the environmental media

With the upsurge in the use of disposable masks during the coronavirus disease pandemic, improper disposal of discarded masks and their negative impact on the environment have emerged as major issues. Improperly disposed of masks release various pollutants, particularly microplastic (MP) fibers, which can harm both terrestrial and aquatic ecosystems by interfering with the nutrient cycling, plant growth, and the health and reproductive success of organisms. This study assesses the environmental distribution of polypropylene (PP)-containing MPs, generated from disposable masks, using material flow analysis (MFA). The system flowchart is designed based on the processing efficiency of various compartments in the MFA model. The highest amount of MPs (99.7 %) is found in the landfill and soil compartments. A scenario analysis reveals that waste incineration significantly reduces the amount of MP transferred to landfills. Therefore, considering cogeneration and gradually increasing the incineration treatment rate are crucial to manage the processing load of waste incineration plants and minimize the negative impact of MPs on the environment. The findings provide insights into the potential environmental exposure associated with the improper disposal of waste masks and indicate strategies for sustainable mask disposal and management.

Advancing plastic pollution hotspotting at the subnational level: Brazil as a case study in the Global South

Identifying sources is crucial for proposing effective actions to combat marine litter pollution. Here, we used an innovative approach to identify hotspots of mismanaged plastic waste (MPW) within Brazil and subsequent leakage to the ocean, based on population density, socio-economic conditions, municipal solid waste management and environmental parameters. We estimated plastic waste generation and MPW for each of the 5570 Brazilian municipalities, which totaled 3.44 million metric tons per year. Then, we estimated the probability of litter mobilization and transport (P) and the relative risk of leakage to the ocean (MPW × P). The Guanabara Bay and La Plata River comprised the main oceanic entry hotspots of litter produced in Brazil. The use of national databases allowed us to increase spatial and temporal granularity, offering a detailed baseline for the application of prevention and mitigation actions. However, overcoming data limitations is still a challenge in Brazil as in other Global South countries.

Estimation of microplastic emission and transfer into Tokyo Bay, Japan, using material flow analysis

To reduce microplastic (MP) discharge into the aquatic environment, it is necessary to properly identify its sources and amounts. Here, specific MP sources, i.e., personal care products (PCPs), fibers from clothes, and tire-wear particles (TWPs) were focused, and MP generations from these sources in the Tokyo Bay watershed, Japan, were estimated based on statistical data on production and reported emission factors of the MP sources and executing considering uncertainty on the data. Potential annual MP emission into Tokyo Bay was estimated to be 10.2 ± 1.6, 38 ± 22, and 1500-1800 tons for PCPs, fibers, and TWPs, respectively. Emissions into Tokyo Bay by assuming MP density and diameter was estimated. For fiber, the fraction to potential emission was estimated at 1.0-2.8 %. This study contributes to determining potential discharge pathways. This will assist in the application of appropriate measures to reduce MP discharge into water bodies.

Understanding the trade-offs of national municipal solid waste estimation methods for circular economy policy

Policies embracing circular economy concepts have taken hold in national legislation around the world. As the number of governments and organizations adopting circular economy policies increases, so does the need for accurate and timely measurement of material resource flows. Since many countries do not have access to centrally reported municipal solid waste (MSW) data, estimation and modeling are critical in evaluating circular economy policy effectiveness. The purpose of this paper is to examine three modeling approaches estimating national MSW data in the United States, including industry-based material flow analysis, waste-extended input-output modeling, and aggregated regional waste reporting. We establish five criteria to guide the analysis through the context of policy monitoring (data quality, flow totality, update frequency, sensitivity to disruption, and product granularity) and use these criteria to analyze and score each model. We then use a literature search to identify five, internationally-implemented options for circular economy policy and determine the data and modeling components that are most helpful in evaluating policy effectiveness. Finally, we provide a crosswalk of the model scores and policy needs to inform the suitability of model selection by policy type. We found that data quality and update frequency are identified as critical components for evaluating circular economy policies within the models evaluated, and can both be fulfilled by aggregated regional waste reporting. Flow totality, sensitivity to disruption, and product granularity requirements vary by both model and policy types. While none of the evaluated models satisfy the combination of requirements for any of the five policies, industry-based material flow analysis offers flow totality for extended producer responsibility, landfill bans, and recycling rate target policies that typically require it. The waste-extended input-output model can provide disruption sensitivity and product granularity as needed for policies like minimum recycled content and market restrictions. Policy developers in areas where strong centralized data collection is not an option should design policy action(s) with modeling tradeoffs in mind, including the potential hybridization of modeling approaches that may provide the most accurate national MSW estimates.

Photovoltaic panel waste assessment and embodied material flows in China, 2000-2050

Solar photovoltaics (PV) is one of the most promising renewable energy sources for climate change mitigation. However, not all green energy installations may not continue to be sustainable after their service life. With the largest installed solar capacity in the world, China is expected to face significant challenges in managing the end-of-life (EoL) PV panels in the coming decades, which have not been well addressed yet.Further, the massive deployment and planning of solar energy systems in China has led to a dramatic increases in demand for raw materials, which places more pressure on the available resources. In this study, we have developed a dynamic, technology-based material flow analysis model to clarify the stock, flow and secondary supply potential of waste PV panel materials in China from 2000 to 2050. The waste generation and circular flow characteristics of the component materials in PV panels are comprehensively investigated, which set important boundary conditions for the recovery and recycling of key materials. The results show that approximately 134 million metric tons (Mt) and 72 Mt of waste PV panels will be cumulatively generated in China up to 2050 under the early loss and regular loss scenarios, respectively. Polysilicon glass accounts for the largest share of PV waste, nearly 64% by weight, followed by aluminum (16%) and steel (11%). Precious metals such as Ag, Ga, In, and Te, account for less than 1% of the total PV waste, but can provide considerable economic benefits if recycled wisely. The potential of secondary resources from PV waste may reduce the supply pressure on the natural materials to some extent, but they could not fully mitigate the material supply resks. We suggest that stakeholders in the solar energy industry should take urgent actions, including recycling technology innovations, effective collection systems and incentive measures, to address the growing challenge of waste PV panels in China.

Measuring the anthropogenic cycles of light rare earths in China: Implications for the imbalance problem

Light rare earth elements (LREEs) are of strategic importance for low carbon transition and decarbonization. However, the imbalance between LREEs exists and a systematic understanding of their flows and stocks is lacking, which impedes the attainment of resources efficiency and exacerbates the environmental burdens. This study examines the anthropogenic cycles and the imbalance problem of three representative LREEs in China, the largest LREEs producer in the world, including cerium (the most abundant), neodymium and praseodymium (the fastest demand-growing). We find that 1) from 2011 to 2020, the total consumption of Nd and Pr increased by 228 % and 223 %, respectively, mainly attributed to the increasing demand of NdFeB, whereas that of Ce increased by 157 %; 2) the supply insufficiency of Nd and Pr under the current quota system accumulated to 138,086 tons and 35,549 tons, respectively, while the oversupply of Ce reached 63,523 tons; and 3) China has become a net importer of LREEs concentrates, and a net exporter of LREEs in the form of intermediate and final products, imposing further burdens to the domestic environment. It is clear that the imbalance of LREEs occurred during the study period, raising urgent needs to adjust the LREEs production quotas, seek other Ce applications, and eliminate illegal mining.

The environmental footprints of the feeds used by the EU chicken meat industry

Chicken meat production in the European Union (EU) causes environmental pressures within and beyond the EU, mostly due to feed consumption. The expected dietary shift from red to poultry meat will drive changes in the demand for chicken feeds and the associated environmental impacts, calling for a renewed attention on this supply chain. By performing a break-down analysis based on material flow accounting, this paper assesses the annual environmental burden caused within and outside of the EU by each single feed consumed by the EU chicken meat industry from 2007 to 2018. The increased feed demand required to support the growth of the EU chicken meat industry over the analyzed period caused a 17 % increase in cropland use - 6.7 million hectares in 2018. Instead, CO₂ emissions linked to feed demand decreased by ~45 % over the same period. Despite an overall improvement in resource and impact intensity, chicken meat production was not decoupled from environmental burden. In 2018, 0.40 Mt. of nitrogen, 0.28 Mt. of phosphorous, and 0.28 Mt. of potassium inorganic fertilizers were implied. Our findings indicate that the sector is not yet compliant with the EU sustainability targets defined in the Farm To Fork Strategy, calling for an urgent need to close existing policy implementation gaps. The EU chicken meat industry's environmental footprints were driven by endogenous factors such as the feed use efficiency at the chicken farming stage and the feed cultivation efficiency within the EU, as well as by exogenous factors such as the import of feed via international trade. Limitations on the use of alternative feed sources, as well as the exclusion of the imports from the EU legal framework constitute a crucial gap, which hamper fully leveraging existing solutions.

A simplified material flow analysis employing local expert judgment and its impact on uncertainty

Material flow analysis (MFA) is an effective tool for waste management, but low- and middle-income countries lack essential data for MFA. This study proposed a simplified MFA (sMFA) utilizing local expert judgment (LEJ) and examining the impact of simplification on its uncertainty. A stochastic sMFA model was developed for nitrogen and phosphorus in urban Mandalay, Myanmar. This model was compared with the intensive MFA (iMFA) model employing intensive surveys for primary data collection. For the total loadings to the environment, the medians of the sMFA were higher by 3% and 11%, respectively, for nitrogen and phosphorus than those of the iMFA. The widths of the 80% confidence intervals of these loadings in the sMFA, normalized by those in the iMFA, were - 0.05 and - 0.11, respectively. The three largest flows to the environment were the same for the two models: on-site sanitation effluent/leakage, greywater, and industrial wastewater. Large median gaps between the models were observed for industrial wastewater, fecal sludge, and human excreta, associated with informal waste management, whereby LEJ did not work well. Overall, the sMFA demonstrated a good estimation of nitrogen and phosphorus flows with limited increase of uncertainty, still requiring focused attention on informal waste streams.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10163-023-01660-5.

Material flow analysis of commercial fishing gears in Taiwan

Marine debris is an international environmental issue, and the growing amount of abandoned, lost, or otherwise discarded fishing gear (ALDFG) is a particular concern. Despite Taiwan's substantial fishing industry, there is a lack of comprehensive understanding of fishing gear. This work conducted a static material flow analysis to estimate the flows and the stocks of fishing gear in Taiwan in 2020, based on government statistics and interviews with fishing gears producing companies, fishermen, and recycling companies. Our findings reveal that the inflow, outflow, and stock of the fishing gears are 8,846 t/a, 4,271 t/a, and 4,575 t/a, respectively. Only 36 % of end-of-life fishing gear is recycled, while the rest is incinerated or landfilled. Additionally, the stock comprises 27 % in use, 23 % in ports, and 50 % entering the ocean. These results underscore the need to increase recycling capacity, prevent loss in oceans, and promote repairs to extend the lifespan of fishing gear.

A first comprehensive estimate of electronic waste in Canada

Detailed analysis of electronic waste (e-waste) generation and composition is of utmost importance for the proper management of growing e-waste stream worldwide, containing both hazardous and valuable materials. Considering the absence of such comprehensive and up-to-date studies in Canada, this work presents the first estimate of put-on-market electrical and electronic equipment (EEE), the in-use stocks of EEE and e-waste generation in Canada from 1971 to 2030 for 51 product categories comprising 198 product types. Using a dynamic material flow analysis (MFA), the put-on-market EEE is estimated based on trade data retrieved from national and international import and export statistics, and the in-use stocks of EEE and the resulting e-waste are calculated using the Weibull distribution function. The results show that the total mass of EEE within the 60-year period is estimated to be 42.3 million tonnes, with an annual average growth rate of approximately 0.5%. By 2030, the total accumulated in-use stock of EEE is estimated to exceed 13 million tonnes. The estimated e-waste over the 60-year timespan is 29.1 million tonnes. The total annual e-waste generation in Canada is calculated to be 252 kilo tonnes (kt) and 954 kt in the years 2000 and 2020 respectively, which is estimated to reach 1.2 million tonnes by 2030. The e-waste generation per capita increased from 8.3 kg in 2000 to 25.3 kg in 2020 and is estimated to reach 31.5 kg by 2030. This quantification provides valuable insights to policymakers for setting up targets for waste reduction and identifying the resource circularity potential for efficient management of e-waste.

Ocean-based sources of plastic pollution: An overview of the main marine activities in the Peruvian EEZ

Marine-based activities are a critical source of plastic waste into the ocean. This is particularly important in countries with a competitive fishing industry, such as Peru. Thus, this study aimed to identify and quantify the major flows of plastic waste accumulating in the ocean from ocean-based sources within the Peruvian Economic Exclusive Zone. A material flow analysis was elaborated to analyze the stock of plastic and its release to the ocean by a set of Peruvian fleets, including the fishing industry, merchant vessels, cruises, and boating vessels. Results show that in 2018 between 2715 and 5584 metric tons of plastic waste entered the ocean. The fishing fleet was the most pollutant, representing approximately 97 % of the total. Moreover, fishing gear loss represented the highest single-activity contribution, although other sources, such as plastic packaging and antifouling emissions, have the potential to become vast sources of marine plastic pollution.

Material Flows and Waste Management of Titanium Products in China from 2005 to 2020

Titanium products play an important and irreplaceable role in national defense and military applications and are considered as strategic resources by many governments. Although China developed a large-scale titanium industrial chain that affects the global market, it is still weak in high-end titanium-based alloys and needs an urgent upgrade. Few policies have been implemented at the national level to explore the development strategies of China's titanium industry and related industries. One major issue is the lack of reliable statistical data, which is essential for setting the national strategies of China's titanium industry. Additionally, waste management and scrap recycling in titanium products manufacturers are not yet considered, which would significantly impact the lifetime of titanium scrap and demand for virgin titanium metal resources. To address this gap, this work has developed a titanium products flow chart for China and presented trends in the titanium industry from 2005 to 2020. The results show that only about 65% to 85% of domestic titanium sponge is finally sold as ingots, and only about 60% to 85% of ingots are finally sold as mills, indicating excessive production has been a characteristic of China's titanium industry. The average recovery ratio of prompt swarf for ingots is about 63%, and that for mills is about 56%, which can be recycled into ingots by remelting, relieving constraints on high-grade titanium sponge and reducing dependence on it to some extent.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40831-023-00667-4.

A decision-support system for recycling of residents' waste plastics in China based on material flow analysis and life cycle assessment

Recycling waste plastics is one of the important ways to save petroleum resources and reduce carbon emissions. However, the current recycling rate of waste plastics is still low. Material flow analysis can help determine the flow of waste plastics, and life cycle assessment (LCA) can be used to quantify environmental impacts. The present study integrates these two methods into the model construction of the residents' waste plastics recycling decision-support system. This model construction is followed by sensitivity analysis of the relevant parameters affecting the performance of the waste plastics recycling system. Finally, the present study forecasts the recycling system's performance and environmental impacts by setting four optimization scenarios based on sensitivity analysis. The results show that in 2019, a total of 8.39 million tons of high-end applications were recovered, carbon emissions during the recycling process were 34.9 million tons, and dioxin emissions were 316.11 g TEQ, with a total emission reduction of 24.47 million tons of CO₂ compared to the original production. Sensitivity analysis shows that the selection rate of waste plastic recycling, the re-sorting rate of waste plastic recycling plant, and the classification recovery rate of mixed waste had relatively high effects on the recovery performance and environmental benefits of the recycling system. In the scenario of comprehensive improvement, in 2035, the recycling volume of high-end applications will rise to 33.96 million tons, the carbon emissions will rise to 64.73 million tons, the dioxin emissions will drop to 165.98 g TEQ, and the carbon emission reduction will rise to 99.06 million tons. This study has a certain guiding role for policy-makers to formulate industry norms and related policies for waste plastic recycling.

Brazilian soybeans as feed for livestock in Europe: an insight into the nitrogen flows

Given the agricultural demand to supply animals with food, the scope of today's soybean production and international trade can influence the nitrogen cycle. Rather than using soybeans from within the region of animal production, animal producers import nutritional supplements from distant growers. This widely opens the biogeochemical cycle of nitrogen, which reduces local recycling and increases carriage of reactive nitrogen via the supply chain. Ultimately, this potentiates the effects of a "nitrogen cascade" process. This study estimates nitrogen flows for Brazilian soybean transported to feed European livestock and attempts to quantify the understanding of how this flow can impact the nitrogen cascade effect. The hypothesis is that the growing trade of Brazilian soybean products is sufficient to spike reactive nitrogen production that can potentially cause distant environmental impacts of the nitrogen cascade. In this respect, the estimation of the nitrogen flows was evaluated using material flow analysis, and the cascade effect was quantified by means of a nitrogen cascade indicator (NCI). Notably, NCI can calculate the released amount of nitrogen in the environment along the entire supply chain of livestock products. NCI-based evaluation of Brazilian soybean products consumed by European livestock indicated the accumulation of nitrogen levels. There was also an increase in nitrogen flows in the Brazilian phase (0.058 Gg in 2007 to 139.86 Gg in 2019 for soybean meal; 584.28 Gg in 2007 to 309.78 Gg in 2019 for soybeans) accompanying a stability in European livestock production. This highlights the necessity for adjustments in nitrogen circularity between all levels of food production and improved strategies of more localised feed autonomy for sustainable global development.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10113-023-02034-1.

A high-resolution dynamic probabilistic material flow analysis of seven plastic polymers; A case study of Norway

Plastic pollution has long been identified as one of the biggest challenges of the 21st century. To tackle this problem, governments are setting stringent recycling targets to keep plastics in a closed loop. Yet, knowledge of the stocks and flows of plastic has not been well integrated into policies. This study presents a dynamic probabilistic economy-wide material flow analysis (MFA) of seven plastic polymers (HDPE, LDPE, PP, PS, PVC, EPS, and PET) in Norway from 2000 to 2050. A total of 40 individual product categories aggregated into nine industrial sectors were examined. An estimated 620 ± 23 kt or 114 kg/capita of these seven plastic polymers was put on the Norwegian market in 2020. Packaging products contributed to the largest share of plastic put on the market (∼40%). The accumulated in-use stock in 2020 was about 3400 ± 56 kt with ∼60% remaining in buildings and construction sector. In 2020, about 460 ± 22 kt of plastic waste was generated in Norway, with half originating from packaging. Although ∼50% of all plastic waste is collected separately from the waste stream, only around 25% is sorted for recycling. Overall, ∼50% of plastic waste is incinerated, ∼15% exported, and ∼10% landfilled. Under a business-as-usual scenario, the plastic put on the market, in-use stock, and waste generation will increase by 65%, 140%, and 90%, respectively by 2050. The outcomes of this work can be used as a guideline for other countries to establish the stocks and flows of plastic polymers from various industrial sectors which is needed for the implementation of necessary regulatory actions and circular strategies. The systematic classification of products suitable for recycling or be made of recyclate will facilitate the safe and sustainable recycling of plastic waste into new products, cap production, lower consumption, and prevent waste generation.

Leverage of resource efficiency over environmental emissions: Case of a megacity in China

Material metabolism in a Chinese megacity, Shanghai, was investigated with an integrated approach. Production-based raw material input, city-wide waste output and carbon emissions were compiled for the period 1995-2020, by computing hundreds of products and by-products. Decoupling of these resource and environmental flows from economic development was assessed, and the socio-economic and technical drivers were decomposed. The research demonstrated a hypothesis that flows of primary resources, waste, and carbon emissions displayed a certain level of synchronicity in the past decades. An order effect was seen with waste indicators usually performing better than carbon indicators, and carbon indicators are better than resource indicators in terms of material/environmental intensity and decoupling. There might be a resource leverage leading to the synchronicity of environmental emissions. Improvement in resource efficiency was decomposed as the most significant driver to urban metabolism, bringing about >33 % of resource reduction, 32 % of carbon mitigation, and 30 % of waste diminution from the 2010 values. A greater extent in emission reduction than resource use was attributed to the decrease of fossil fuels share in total resource use and carbon intensity per energy consumption. Continuous increase in post-use waste flows caused a rebound of waste indicators in the recent five-year period (2016-2020) and broke up the synchronicity. This potentially foresees the shift of material metabolism from production to consumption side in major cities in China and calls for reforms of environmental policies.

Environmental assessment of casual dining restaurants in urban and suburban areas of peninsular Malaysia during the COVID-19 pandemic

Food waste has been considered a global problem due to its adverse impacts on food security, the environment, and the economy; hence needs urgent attention and action. Its generation is expected to increase as the world population grows rapidly, leading to more global waste. This study sought the impacts of the COVID-19 outbreak on the 1-week operation of selected casual dining restaurants in urban (Ampang, Kuala Lumpur) and suburban areas (Kota Bharu, Kelantan and Jasin, Melaka) of Peninsular Malaysia, as the local community adjusted to life with COVID-19. The food waste in this study was classified into three categories: preparation loss, serving loss, and customer's plate waste. Our material flow analysis revealed that the highest food loss at these locations came from preparation loss (51.37%), followed by serving loss (30.95%), and preparation loss (17.8%). Meanwhile, the total average electricity consumption and its carbon footprint for Ampang were 127 kWh and 13.87 kgCO₂e, Kota Bharu 269.8 kWh and 29.47 kgCO₂e, and Jasin 142.2 kWh and 15.54 kgCO₂e, respectively. As for water, Ampang exhibited 22.93 m³ total average consumption and 7.91 kgCO₂e greenhouse emissions from this source, Jasin consuming 17.11 m³ of water and releasing 5.88 kgCO₂e of carbon footprint, while Kota Bharu emitted 20.21 kgCO₂e of greenhouse gases from its 58.71 m³ water consumption. Our findings indicate a major 'food leak' at the preparation stage, from which the waste could be utilised as livestock feed, and that electricity consumption is a greater carbon emitter than water consumption, suggesting a need for improvement to the kitchen practices and equipment.

An integrated framework for industrial symbiosis performance evaluation in an energy-intensive industrial park in China

Industrial symbiosis (IS) is an important tool to achieve green development for industrial parks. It is necessary to evaluate the IS performance for monitoring and managing the development of IS system. This study proposed an integrated framework to assess the IS performance based on the energy-intensive industrial park. Firstly, we established a Conceptual model of symbiotic coupling of three industries (iron and steel, thermal power, and cement). Then, the conceptual model was applied to extend the existing IS system in the energy-intensive industrial park. Finally, the IS performance of the extended IS system was evaluated. We verified this framework in Red flag cannel park (RFCP). The IS performance assessment in RFCP found that the existing IS activities produced significant multiple benefits and environmental impact reduction. For example, the existing IS activities produced 970.20 kt of low-carbon benefits, which accounted for 19% of the CO₂ emissions in RFCP. However, after extending the existing symbiotic system combined with the conceptual model proposed in this study, we found that there still was a large amount of symbiotic potential (the reuse of waste heat, BF slag, gypsum) waiting to be developed in RFCP. In addition, we also found that the resilience of existing IS network in RFCP was weak and need to be further perfected. In general, in the further development and perfection of IS system in RFCP, the manager should not only focus on the development of IS activities among energy-intensive enterprises but also strive to foster more influential enterprises to enhance the anti-risk ability of IS network. The result indicates the integrated framework can provide support for the development and perfection of IS system in energy-intensive industrial parks.

A generic scenario analysis of end-of-life plastic management: Chemical additives

Plastic growing demand and the increment in global plastics production have raised the number of spent plastics, out of which over 90% are either landfilled or incinerated. Both methods for handling spent plastics are susceptible to releasing toxic substances, damaging air, water, soil, organisms, and public health. Improvements to the existing infrastructure for plastics management are needed to limit chemical additive release and exposure resulting from the end-of-life (EoL) stage. This article analyzes the current plastic waste management infrastructure and identifies chemical additive releases through a material flow analysis. Additionally, we performed a facility-level generic scenario analysis of the current U.S. EoL stage of plastic additives to track and estimate their potential migration, releases, and occupational exposure. Potential scenarios were analyzed through sensitivity analysis to examine the merit of increasing recycling rates, using chemical recycling, and implementing additive extraction post-recycling. Our analyses identified that the current state of plastic EoL management possesses high mass flow intensity toward incineration and landfilling. Although maximizing the plastic recycling rate is a reasonably straightforward goal for enhancing material circularity, the conventional mechanical recycling method requires improvement because major chemical additive release and contamination routes act as obstacles to achieving high-quality plastics for future reuse and should be mitigated through chemical recycling and additive extraction. The potential hazards and risks identified in this research create an opportunity to design a safer closed-loop plastic recycling infrastructure to handle additives strategically and support sustainable materials management efforts to transform the US plastic economy from linear to circular.

Separate collection rates for plastic packaging in Austria - A regional analysis taking collection systems and urbanization into account

According to the EU Circular Economy Package, recycling of plastic packaging waste (PPW) has to be enhanced significantly by 2025 and 2030. Although a set of measures will be required along the whole value chain of plastic packaging, the process of separate collection remains the backbone. Hence, a detailed understanding of the performance of current separate collection systems is crucial. As a case study, the separate collection of PPW was analyzed within a single country, Austria, where a variety of collection procedures are implemented. By using the method of material flow analysis, separate collection rates in terms of quantities and qualities were analyzed for separate collection systems of different settlement patterns, target fractions, and service levels provided. Results show that the highest performance was achieved in systems that cover mainly rural areas and where all plastic packaging wastes are collected through curbside collection, with separate collection rates of 74-77%. With additional collection via collection centers, these values increased to 78%-83%. In comparison, the results for urban areas showed the lowest separate collection rate of 56%. In the case that separate collection targeted plastic bottles only, maximum collection rates of around 50 % were observed, with the tendency towards higher collection rates if co-mingled with metals. To enhance separate collection, a general shift to the target fraction "all plastic packaging" instead of "plastic bottles only" is crucial. Modelling of optimized collection systems in all Austrian regions would lead to a theoretical total separation collection rate of 74%.

Sources, sinks and transformations of plastics in our oceans: Review, management strategies and modelling

Currently, 60-80 % of litter is plastic, and almost 10 % ends up in the ocean directly or indirectly. Plastics often suffer from photooxidation producing microplastics and these microplastics derived from the breakdown of larger plastics are called secondary microplastics. These compounds simply cannot be extracted from the oceans, and once mixed, they enter the food chain and may have toxic effects. This work reviews the current existing information on the topic in the scientific literature. Then, the current plastic management strategies in the marine environment are analysed, with the objective of identifying possible needs and improvements from a sustainable point of view, and to define new approaches. Simultaneously, a material flows analysis in different media of the marine environment is carried out using system dynamics. A preliminary model of plastics mobilization into the ocean to other media of the marine environment (like sediments and biota) is developed and validated with the existing data from the previous steps of the work. This work expands the current knowledge on the plastics management, their transformations and accumulation in the marine environment and the harmful effects on it. Likewise, preliminary dynamic model of mobilization of plastics in the ocean is implemented, run, and validated. The developed model can be used to predict trends in the distribution of the plastics in the ocean with time. In addition, the most important reservoirs of plastics in the ocean can be observed. Although plastics undergo transformations in the marine environment, it is not a means of disposal since most of them are non-biodegradable. Most plastics accumulate on the seabed. The proportion of microplastics found in sediments is higher than that of macroplastics.

Circular material flow in the intensive care unit-environmental effects and identification of hotspots

PURPOSE

The healthcare sector is responsible for 6-7% of CO₂ emissions. The intensive care unit (ICU) contributes to these CO₂ emissions and a shift from a linear system to a circular system is needed. The aim of our research was to perform a material flow analysis (MFA) in an academic ICU. Secondary aims were to obtain information and numbers on mass, carbon footprint, agricultural land occupation and water usage and to determine so-called "environmental hotspots" in the ICU.

METHODS

A material flow analysis was performed over the year 2019, followed by an environmental footprint analysis of materials and environmental hotspot identification.

RESULTS

2839 patients were admitted to our ICU in 2019. The average length of stay was 4.6 days. Our MFA showed a material mass inflow of 247,000 kg in 2019 for intensive care, of which 50,000 kg is incinerated as (hazardous) hospital waste. The environmental impact per patient resulted in 17 kg of mass, 12 kg CO₂ eq, 300 L of water usage and 4 m² of agricultural land occupation per day. Five hotspots were identified: non-sterile gloves, isolation gowns, bed liners, surgical masks and syringes (including packaging).

CONCLUSION

This is the first material flow analysis that identified environmental risks and its magnitude in the intensive care unit.

A critical review of microplastic degradation and material flow analysis towards a circular economy

The resilience and low cost of plastics has made their usage ubiquitous, but is also the cause of their prevalence and longevity as waste. Plastic pollution has become a great concern to the health and wellbeing of ecosystems around the world; microplastics are a particular threat, due to their high mobility, ease of ingestion by wildlife, and ability to adsorb and carry toxic contaminants. Material flow analysis has been widely applied to examine stocks and flows of materials in other industries, and has more recently been applied to plastics to examine areas where waste can reach the environment. However, while much research has gone into the environmental fate of microplastics, degradation strategies have been a lesser focus, and material flow analysis of microplastics has suffered from lack of data. Furthermore, the variety of plastics, their additives, and any contaminants pose a significant challenge in degrading (and not merely fragmenting) microplastic particles. This review discusses the current degradation strategies and solutions for dealing with existing and newly-generated microplastic waste along with examining the status of microplastics-based material flow analysis, which are critical for evaluating the possibility of incorporating microplastic waste into a circular economy. The degradation strategies are critically examined, identifying challenges and current trends, as well as important considerations that are frequently under-reported. An emphasis is placed on identifying missing data or information in both material flow analysis and degradation methods that could prove crucial in improving understanding of microplastic flows, as well as optimizing degradation strategies and minimizing any negative environmental impact.

Systematic data-driven exploration of Austrian wastewater and sludge treatment - implications for phosphorus governance, costs and environment

Within the new policy framework shaped by the EU Green Deal and the Circular Economy Action Plans, the field of wastewater and sludge treatment in Europe is subject to high expectations and new challenges related to mitigation of greenhouse gas emissions, micropollutant removal and resource recovery. With respect to phosphorus recovery, several technologies and processes have been thoroughly investigated. Nevertheless, a systemic and detailed understanding of the existing infrastructure and of the related environmental and economic implications is missing. Such basis is essential to avoid unwanted consequences in designing new strategies, given the long lifespan of any infrastructural change. This study couples a newly collected and highly detailed database for all wastewater treatment plants in Austria bigger than 2000 population equivalent with a combination of analyses, namely Substance Flow Analysis with focus on nutrient and metal distribution in different environmental and anthropogenic compartments, Energy Flow Analysis, Life Cycle Assessment and cost estimation. The case study of Austria is of special interest, given its highly autonomous administration in federal states and its contrasting traits, ranging from flat metropolitan areas like Vienna to low-populated alpine areas. The significant impact of electricity demand of wastewater treatment on the overall Cumulative Energy Demand (CED) shows the importance of optimization measures. Further, the current system of wastewater and sludge disposal have a low efficiency in recovering nutrients and in directing pollutants as heavy metals into final sinks. Sludge composting with subsequent use in landscaping does not only show an unfavorable environmental balance, but it is the only relevant route leading to additional CED and Global Warming Potential emissions and to the highest transport volume. Altogether, the outcomes of this study provide a sound basis to further develop national strategies for resource recovery aimed to optimize trade-offs between different economic and environmental objectives.

Material flow analysis and recycling performance of an improved mechanical recycling process for post-consumer flexible plastics

Increasing the recycling rates for post-consumer flexible plastics (PCFP) waste is imperative as PCFP is considered a difficult-to-recycle waste with only 17 % of PCFP effectively recycled in Europe. To tackle this pressing issue, improved mechanical recycling processes are being explored to increase the recycling rates of PCFP. One interesting option is the so-called quality recycling process (QRP) proposed by CEFLEX, which supplements more conventional mechanical recycling of PCFP with additional sorting, hot washing, improved extrusion, and deodorization. Material flow analysis (MFA) model is applied to assess the performance of QRP. Four performance indicators related to quantity (process yield and net recovery) and quality (polymer grade and transparency grade) are applied to measure the performance of three PCFP mechanical recycling scenarios. The results are compared against the conventional recycling of PCFP, showing that QRP has a similar process yield (64 % - 66 %) as conventional recycling (66 %). The net recovery indicator shows that in QRP higher recovery rates are achieved for transparent-monolayer PCFP (>90 %) compared to colored-multilayer PCFP (51 % - 91 %). The quality indicators (polymer and transparency grades) demonstrate that the regranulates from QRP have better quality compared to the conventional recycling. To validate the modeling approach, the modeled compositional data is compared with experimental compositional analyses of flakes and regranulates produced by pilot recycling lines. Main conclusions are: (i) although yields do not increase significantly, extra sorting and recycling produces better regranulates' quality (ii) performing a modular MFA gives insights into future recycling scenarios and helps in decision making.

Generation estimation and material flow analysis of retired mobile phones in China

The generation estimation of retired mobile phones is launched with the sales and new method using the revised sales data and amount of the subscribers. Several assumptions have been made due to the insufficient sources of the data. The sales data of legal mobile phones are calculated with the authoritative and continuous official data. The sales data of smuggled and counterfeit mobile phones in China are also estimated based on the behavior data collected from the questionnaires. The results of generation estimation show that there are 636.52 million mobile phones retired in 2020, compared with 14.44 million in 1999 and several negative values in 2000, 2001, and 2008. The annual total mass of retired mobile phones in China escalated with the contributions of both the increasing generation amount and constant mass of the single unit. There are 50,921.60 ton of mobile phones retired in 2020 compared with 1155.20 ton in 1999, while the peak is 58,131.20 ton in 2019. There are 26,066.80 ton of retired mobile phones are stockpiled in 2020, while 16,152.40 ton and 8702.40 ton of retired mobile phones are reused as a whole unit and recycled, respectively. In the retired mobile phones that are recycled, 4600.50 ton material is recovered and 1216.50 ton components are reused, while 2885.40 ton residues need final disposal. The amount and dynamic characteristics of metals in the retired mobile phones are also calculated. Based on the results, several policy implications are made to improve sustainable management system of retired mobile phones in China.

Exploring potential opportunities for the efficient development of the cobalt industry in China by quantitatively tracking cobalt flows during the entire life cycle from 2000 to 2021

Owing to its key role in high-tech industry and clean energy technology, cobalt has been regarded as a critical material in many countries. In this paper, material flow analysis was used to quantitatively track cobalt material flows in China throughout the entire life cycle from 2000 to 2021. Based on data pertaining to cobalt commodity trade, cobalt loss during raw material processing, and recovered cobalt, we analysed the actual cobalt consumption in China. During the study period from 2000 to 2021, the main findings were as follows: (1) China's cobalt raw material imports accounted for 84.7% of the total raw materials acquired, while the export of cobalt-containing end products amounted to 32.6% of the total production. (2) China's cumulative net import of all cobalt commodities reached 561 kt, and battery products accounted for 73.3% of the total cobalt consumption. (3) China recovered 77 kt of cobalt from end-of-life products, while 327 kt of cobalt was not recovered. (4) The cumulative cobalt loss during raw material processing reached 288 kt, with the highest loss occurring in refining (51.0%), followed by manufacturing and fabrication (26.5%), beneficiation (12.3%), and ore mining (10.2%). The overall utilization efficiency of cobalt was 73.8% throughout the entire life cycle. (5) China's actual cobalt consumption reached 497 kt, accounting for 51.9% of the apparent cobalt consumption. Moreover, 61.1% of the cobalt products produced in China was consumed domestically, while 38.9% was exported. The massive export of cobalt commodities resulted in China bearing a disproportionate responsibility for carbon emission reduction. The research results can provide a scientific reference for the reasonable adjustment of the trade structure of cobalt commodities and realization of the economic and efficient utilization of cobalt resources in China.

Win-Win: Anthropogenic circularity for metal criticality and carbon neutrality

Resource depletion and environmental degradation have fueled a burgeoning discipline of anthropogenic circularity since the 2010s. It generally consists of waste reuse, remanufacturing, recycling, and recovery. Circular economy and "zero-waste" cities are sweeping the globe in their current practices to address the world's grand concerns linked to resources, the environment, and industry. Meanwhile, metal criticality and carbon neutrality, which have become increasingly popular in recent years, denote the material's feature and state, respectively. The goal of this article is to determine how circularity, criticality, and neutrality are related. Upscale anthropogenic circularity has the potential to expand the metal supply and, as a result, reduce metal criticality. China barely accomplished 15 % of its potential emission reduction by recycling iron, copper, and aluminum. Anthropogenic circularity has a lot of room to achieve a win-win objective, which is to reduce metal criticality while also achieving carbon neutrality in a near closed-loop cycle. Major barriers or challenges for conducting anthropogenic circularity are deriving from the inadequacy of life-cycle insight governance and the emergence of anthropogenic circularity discipline. Material flow analysis and life cycle assessment are the central methodologies to identify the hidden problems. Mineral processing and smelting, as well as end-of-life management, are indicated as critical priority areas for enhancing anthropogenic circularity.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material is available in the online version of this article at 10.1007/s11783-023-1623-2 and is accessible for authorized users.

Analysis of iron composite flow in China

Iron is an important metal material that is crucial to social and national economic development. In order to understand iron's material flow, energy flow, and value flow in China, a composite flow framework is here established. Based on this framework, the concept of price is introduced, and China is taken as an example to study the composite flow of iron in 2018. The results showed the following. First, as iron moved down the industrial chain, its material flow decreased gradually, while the price continued to rise. Second, the annual loss of raw materials from iron processing was 150-200 million tons, and scrap iron had great potential for secondary utilization. Third, China had a trade deficit in terms of importing raw materials and exporting products, but it also had a trade surplus in trade volume. Finally, China imported iron-containing goods at high prices but exported iron-containing goods at low prices. This was due to the lack of high-end science and technology, which made China less competitive in the international market.

The Development Scenarios and Environmental Impacts of China's Aluminum Industry: Implications of Import and Export Transition

Aluminum is widely used in buildings, transportation, and home appliances. However, primary aluminum production is a resource, energy, and emission-intensive industrial process. As the world's largest aluminum producer, the aluminum industry (ALD) in China faces tremendous pressure on environmental protection. This study combines material flow analysis and scenario analysis to investigate the potential of resource conservation, energy saving, and emission reduction for China's ALD under the import and export trade transition. The results show China's per capita aluminum stock will follow a logistic curve to reach 415 kg/capita by 2030. However, unlike the continued build-up of stocks, domestic demand for aluminum will peak at 44 million tons (MT) in 2025 and fall to 36 MT in 2030. The scenario analysis reveals that China's primary aluminum output could peak in 2025 at around 52 MT if the restrictions are not implemented (Scenario A). Compared to Scenario A, demand for primary aluminum is effectively limited in Scenarios B and C where exports of aluminum products are reduced. Correspondingly, both scenarios also have obvious benefits in reducing the environmental load of China's ALD. Besides, if hydropower used in aluminum electrolysis increases to 25% by 2030, the total GHG emissions in 2030 will be reduced by 12%. Therefore, promoting import/export and energy mix transformation can become an essential means for the sustainable development of China's ALD.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40831-022-00582-0.

Tire wear particle emissions: Measurement data where are you?

Tire wear particle (TWP) emissions are gaining more attention since they are considered to contribute a major share to the overall microplastic emissions and are suspected to be harmful to flora, fauna and humans. Hence, recent studies derived country-based TWP emissions to better understand the significance of the problem using either tire emission factors (EF) or a material flow analysis (MFA) of tires. However, all 14 country-based TWP emission studies found and published since the year 2000 base their calculation on other studies rather than own measurements. Therefore, we started to search for the actual TWP measurements which the 14 studies would rely on. As a result, we found a network of 63 studies which were used to derive TWP emissions in different countries and regions. Only in few cases (12%) TWP emission studies reference directly to a measurement study to derive TWP emissions, but mostly (63%) they rely on reviews or summarizing studies. Additionally, we could not obtain 25 studies in the analysed network. In total we found nine studies which actually measured TWP emissions. Out of these four studies originate from the 1970s, one analysed only light vehicles and one only considered buses. Thus, only three non peer-reviewed studies were considered to show trustful results which were cited a maximum of three times in the network. The obtained 14 country-based studies suggest TWP emissions of about 1.3 kg capita^-1 year^-1 for the EF approach and 2.0 kg capita^-1 year^-1 for the MFA approach (overall range: 0.9-2.5 kg capita^-1 year^-1). Consequently, we call for an urgent need to minimize uncertainties of TWP emission estimates to better understand the contribution of TWP to the overall microplastic pollution of the environment. A better understanding about quantities could also help to better address the risk of environmental pollution by TWP.

Material flow analysis of plastic waste in the gulf co-operation countries (GCC) and the Arabian gulf: Focusing on Qatar

Global plastic waste production has increased dramatically in recent years, both globally and regionally, having a multitude of adverse effects on the environment and human health. However, little attention has been directed to this problem in the Arabian Gulf region. This study aims to delineate and map the status of the plastic waste problem in the Gulf Co-operation Countries (GCC), with a focus on Qatar. The study focuses on the plastic waste in the marine environment, depicting the different types, sizes and shapes of plastic particles found in the Arabian Gulf. To depict the flow of plastic waste, a generic material flow diagram was built using a material flow analysis software named STAN, in which transfer coefficients were assigned based on existing scientific literature and estimations built on data from local industries and recycling facilities. The recovery and recycling efforts that have been made by the different GCC countries, in efforts to reduce plastic waste and minimize the risk of plastic on the environment are analyzed, too. Our analyses indicate that approximately 11.9 Mt ± 595.395 Kt of plastic waste is produced annually in the GCC region, of which only 23 ± 15% is recycled, indicating that improvements are yet to be made in the recovery, recycling and treatment of plastics in the region. However, in Qatar, a higher percentage of plastics (40 ± 10%) is recovered-recycled with efforts to treat plastics and reuse it to generate energy.

Retrospective and prospective material flow analysis of the post-consumer plastic packaging waste management system in Flanders

The post-consumer plastic packaging waste management in Flanders was analyzed by performing a retrospective material flow analysis, covering an extensive period from 1985 to 2019. In addition, a prospective material flow analysis of 32 improvement scenarios was performed, based on expected changes in the waste management system. Mass recovery rates were calculated based on different interpretations of the calculation rules. Moreover, various cascading levels were identified to differentiate between the quality level of the secondary applications. The mass recovery rate including only recycling evolved from a value of 0% in 1985 to 31% in 2019 and could be increased to 36-62% depending on the improvement scenario selected. However, the different interpretations of the calculation rules led to a variation of up to 20 and 41% on this mass recovery rates for the retrospective and prospective analysis, respectively. The introduction of monostream recycling for additional post-consumer plastic packaging flows, such as low-density polyethylene, did not lead to increasing mass recovery rates, if no differentiation for the cascading levels was made. The Belgian recycling target of 65% for 2023 will be challenging if the strictest calculation method needs to be followed or if the improvements in the Flemish post-consumer plastic packaging waste system do not follow the best-case collection scenarios under the given assumptions. To harmonize the calculation and monitoring of these targets, clear calculation rules need to be accompanied with a harmonized monitoring system over the entire waste management system.

Nitrogen flow in the food production and consumption system within the Yangtze River Delta city cluster: Influences of cropland and urbanization

Intensive anthropogenic activities associated with the food production and consumption system (FPC) drive massive reactive nitrogen inputs to city clusters resulting in serious nitrogen (N) pollution. We conducted a substance flow analysis to examine N flows in the FPC within the Yangtze River Delta city cluster from 2011 to 2019. The total N input and output showed parabolic downward trends, with decreases from 4008.27 to 3472.57 Gg N yr^-1 and 3518.65 to 3061.29 Gg N yr^-1, respectively; chemical fertilizer (54.7%-57.3%) and N loss (87.1%-90.9%) were the primary components of N input and output, respectively. The decreased total N input was related to reductions in chemical fertilizers and livestock numbers. However, a notable increase in N input to the human subsystem was observed, and urbanization was associated with increased N inputs within the human subsystem via higher amounts of food N consumed per capita and proportions of animal-based food N consumed. Total N loss initially increased then decreased; Nantong, Jiaxing, Shanghai, Yancheng, Taizhou, and Yangzhou were the top six cities in N loss intensity. The proportion of cultivated land area, livestock numbers per unit area, and population density were important factors influencing the spatial heterogeneity of N loss intensity. Twenty-six cities were divided into six groups based on their N loss composition, and various N management strategies were proposed. This study highlights the strong influences of cropland and urbanization on N flows within the FPC, which can be used as a reference for N management at a city cluster scale.

Quantity and fate of synthetic microfiber emissions from apparel washing in California and strategies for their reduction

Synthetic microfibers have been identified as the most prevalent type of microplastic in samples from aquatic, atmospheric, and terrestrial environments across the globe. Apparel washing has shown to be a major source of microfiber pollution. We used California as a case study to estimate the magnitude and fate of microfiber emissions, and to evaluate potential mitigation approaches. First, we quantified synthetic microfiber emissions and fate from apparel washing in California by developing a material flow model which connects California-specific data on synthetic fiber consumption, apparel washing, microfiber generation, and wastewater and biosolid management practices. Next, we used the model to assess the effectiveness of different interventions to reduce microfiber emissions to natural environments. We estimate that in 2019 as much as 2.2 kilotons (kt) of synthetic microfibers were generated by apparel washing in California, a 26% increase since 2008. The majority entered terrestrial environments (1.6 kt), followed by landfills (0.4 kt), waterbodies (0.1 kt), and incineration (0.1 kt). California's wastewater treatment network was estimated to divert 95% of microfibers from waterbodies, mainly to terrestrial environments and primarily via land application of biosolids. Our analysis also reveals that application of biosolids on agricultural lands facilitates a directional flow of microfibers from higher-income urban counties to lower-income rural communities. Without interventions, annual synthetic microfiber emissions to California's natural environments are expected to increase by 17% to 2.1 kt by 2026. Further increasing the microfiber retention efficiency at the wastewater treatment plant would increase emissions to terrestrial environments, which suggests that microfibers should be removed before entering the wastewater system. In our model, full adoption of in-line filters in washing machines decreased annual synthetic microfiber emissions to natural environments by 79% to 0.5 kt and offered the largest reduction of all modeled scenarios.

A high-resolution dataset on the plastic material flows in Switzerland

A material flow analysis of the main plastic types used and arising as waste in Switzerland in 2017 is conducted, including consideration of stock change. Seven main plastic application segments are distinguished (packaging; building and construction; automotive; electrical and electronic equipment; agriculture; household items, furniture, leisure and others; and textiles), further divided into 54 product subsegments. For each segment, the most commonly used plastic types are considered, in total including eleven plastic types (HDPE, LDPE, PP, PET, PS, PVC, ABS, HIPS, PA, PC, and PUR). All product life cycle stages are regarded, including the determination of the product subsegments in which the individual post-consumer secondary materials obtained from mechanical recycling are applied. The underlying data are gathered from official statistics and administrative databases, scientific literature, reports by industry organizations and research institutions, websites, and personal communication with stakeholders. The compiled data are then reconciled. All flow data are provided and depicted in two Sankey diagrams: one diagram shows the material flows on a product-subsegment level and the second one on a plastic-type level. Users may retrieve the data with a script and transfer them into a relational database. The present material flow analysis data are used as a basis for the scenario analysis in Klotz et al. [1]. Besides scenario modelling, the data can be used in conducting life cycle assessments. Both utilizations can serve as a support for designing future plastic flow systems.